PUBLICATION NATURAL VENTILATION SYSTEM … Gilberts Mistrale Natural ... Type 2 - Exhaust Turret Terminal with Mounting Sleeve ... position (electric actuator illustrated) 6. 7

NATURAL VENTILATION SYSTEMThe Complete Solution

NATURAL VENT 2

FEB 2010

PUBLICATION

Mistrale (Cooling Katabatic Wind)Natural ventilation, unlike mechanical fan forced

ventilation, simply uses the naturally occurring

pressure differential forces of air movement, wind

and buoyancy to deliver a steady supply of fresh air

for building ventilation and space cooling.

In an environment where energy conservation is

at a premium this sounds ideal�and it is! Naturally

ventilating a building actually offers the best of both

worlds combining little or no energy consumption with

low capital costs, whilst still providing adequate fresh

air and comfort temperature conditions throughout the

year.

With plant room also eliminated, services space

minimised and lower servicing/maintenance costs

Natural Ventilation now makes for one the most

practical choices of the day.

Modern buildings with their low u values and high

heat gains typically have a high cooling requirement.

The climate in the UK and many parts of central

through Northern Europe is perfectly suited for

Natural Ventilation applications with low extremes

of temperature providing an ample supply of fresh

cooling air even in a typical summer.

Natural Ventilation strategies are founded on two

basic operational strategies and essentially comprise

either of wind driven systems or a buoyancy (stack

effect) system. The Gilberts Mistrale Natural

Ventilation range embraces both of these

philosophies.

In some locations and building designs wind alone

can be used as the principal driving force.

In wind driven systems the air on the wind ward side

of the building creates a positive pressure with

corresponding negative pressure generated on the

leeward side. Using this effect air can be easily drawn

through the building. Although wind driven systems

can be effective, building design, orientation and

location factors are important here for a successful

result.

Although helpful, Natural ventilation systems

do not need wind to operate satisfactorily.

More effective strategies employ alternative buoyancy

and stack effects instead to provide the ventilation

base. Instead of wind pressure a vertical stack or

shaft in the building can be utilised to allow warmer

air to migrate and rise through the building to high

level outlets whilst drawing fresh cool air in from low

level. Stack ventilation does not rely on the wind at all

and, because it does not rely on the pressure or

direction of the wind either, offers greater reliability as

well as more flexibility on the placement and location

of the air intakes.

Gilberts Natural Ventilation engineers are on hand

to discuss whether wind driven, stack driven or,

in more challenging areas, consideration of a mixed

mode system that includes mechanical ventilation, is

the most appropriate strategy for your project.

Stack Driven

Natural Ventilation Strategies

Wind Driven

Wind wardCool fresh

air in

Cool fresh

air in

Warm stale

air rises

Warm stale

air out

Warm stale

air out + VE

pressure

Cool

fresh

air in

Stale

air

out

- VE

pressure

Lee ward

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Introduction

Mistrale system strategies

Mistrale Model A

Mistrale Model B

Mistrale Model C

Mistrale Model D

Mistrale Model E

Mistrale Model F

Mistrale Natural Ventilation Components

Intake Louvres

Volume Control Damper

Heating or Cooling Coil

Fascia Grilles

Roof Top Penthouse Turret Louvres

Type 1 - Exhaust Turret Terminal

Type 2 - Exhaust Turret Terminal with Mounting Sleeve

Type 3 - Exhaust Terminal with Mounting Sleeve and

Damper

Type 4 - Wind Driven Terminal

Type 5 - Wind Driven Terminal with Air Distribution Plenum

Penthouse Louvre Performance Data

Acoustic Silencer

Acoustic Information

Mistrale Natural Ventilation Control

Control Strategy

Control Display Options

System Performance

Ordering Specifications

4

Low Level

Low level floor installations, whether in glazing or the wall

structure itself, is the most popular installation location

providing for optimum air flow and comfort

conditions. Cooling outside air will be

drawn through the assembly at low

room level ventilating through higher

level wall grille and damper

assemblies into the stack.

Since the airflows are usually

unrestricted this typically

maximises the air movement

efficiency.

Under Floor

An under floor ventilation arrangement gives the opportunity

to keep walls and window areas free or can simply be used

for areas where external wall areas may not be available.

A louvre intake and damper arrangement draws air into

the floor void and distributes this into the room at floor

level through standard design floor grilles. The cool

fresh denser air displaces the lighter warm air

upwards where it is extracted through high level wall

grille and damper assemblies into the stack. Under

floor systems which have fewer depth/thickness

restrictions also give greater opportunity for acoustic

insulation in areas where external noise might

be a problem.

CeilingSimilar to an under floor installation a ceiling displacement

arrangement gives the opportunity to keep walls and window

areas free and can be used for areas where wall space may

not be available. Cooling air is drawn in through a louvre and

damper arrangement for distribution through traditional

ceiling diffuser air outlets or even laminar flow outlets.

The cooler air sinks displacing the warmer stale air which

can then be drawn out into the stack through higher level

wall grille and damper arrays. Because natural

ventilation relies mostly on a buoyancy effect

ceiling systems are inherently less efficient

unless they are also wind driven. However

ceiling systems again have fewer

depth/thickness restrictions and so also

give greater opportunity for acoustic

insulation in areas where external noise

might be a problem.

Mistrale System Strategies

Natural ventilation systems comprise of a number of key

components. Although windows can be used for ventilation the

Gilberts Mistrale system does not feature a window based

strategy. Window based systems can be simple but are also

inherently disadvantaged. With natural ventilation systems often

using low overnight temperatures for cooling, opening windows

are usually not desirable from a security aspect. Other issues

such as noise penetration and water ingress are also difficult to

avoid and window motorisation can also compromise aesthetics.

Windows may also not offer the fine levels of control and

balance required for a modern ventilation system. For this

reason Gilberts Mistrale System focuses on using optimum,

measured performance components that include a secure intake

louvre, a fully controllable insulated volume control damper, a

heating or cooling coil, a covering fascia grille and

intake/exhaust penthouse roof turrets.

A typical Mistrale natural ventilation assembly comprises of an

intake louvre, air regulating damper and fascia grille. Installation

options are varied with the opportunity for window, low level

floor, under floor or even over ceiling installation. This installation

strategy will affect your detailed choice of louvre, damper and

fascia components.

5

Floor Swirl DisplacementFloor outlet swirl diffusers allow fresh natural

ventilation air to enter the space from the floor

void. The cool fresh air will displace the warmer

stale air which can evacuate through the transfer

grilles into the stack. Standard linear bar type floor

grilles which have a lower pressure resistance, can

also be utilised.

Ceiling Laminar Flow DiffusersCeiling laminar flow diffusers allow natural

ventilation air to enter the space from the ceiling

void. The cool fresh air will intermix and sink

displacing the warmer stale air which can evacuate

though the transfer grille into the stack.

TransferThe transfer grille is usually

fitted at high level within the

conditioned space.

This provides a pathway for

the warm stale exhaust air to

rise and pass from the room

space into the ventilation stack.

Exhaust Wall OutletHigh level exhaust outlets

offer an alternative to roof top

turrets and allow the warm

stale air entering the stack

to rise and ventilate to the

outside.

Penthouse Exhaust TurretRoof level exhaust turrets are the popular

means to allow the warm stale air in the stack

to ventilate. These turrets can also be set up

for use as combined fresh air intake and

exhaust outlets when used in wind driven

systems.

Stack

Mistrale Natural Ventilation

Mistrale Model AIntake unit with Heating or Heating/Cooling

Coil

Model A is the most popular natural ventilation unit choice

and is primarily intended as a supply/intake unit for low

level mounting installation. A low level model provides for

optimum air flow and comfort conditions as cooling outside

air will be drawn through the assembly at low room level

with the warmer air then ventilating through higher level

wall grille and damper assemblies (See Model F) into the

stack. Units are typically fitted with a coil to allow for initial

heating of the air, when required, before entering the room.

Standard arrangement (as illustrated) comprises

• External Louvre - Standard high efficiency

weather louvre with choice of flange, channel

or window beading fixing frame options.

• Insulated Volume Control Damper - Manual

or Motor control.

• Heating/Cooling Coil.

• Decorative Fascia Grille - Standard routed or perforated

face pattern fascia panel in standard or low surface

temperature format.

Size Range

Effective damper size.

Width 300, 800 or 1300mm

Height 206, 406 or 606mm

Structural opening sizes

Damper width + 260mm

Damper height + 110mm

Finish

Both the external louvre and the fascia grille finished to

standard BS/RAL colours.

Our Mistrale Natural Ventilation System has been developed

with maximum project flexibility in mind. Different buildings

and structural designs combined with the building location

and design purpose present a wide variety of factors which

can affect system selection. As standard we offer 6 model

configurations (Model A to Model F) but the ability to also

pick and mix the various components of Mistrale enables us

to adapt our product for a multitude of different installations.

Louvre Glazing

Bead

Channel Louvre Flanged Louvre

Dim ‘A’ WG/100 - 121mm

WH/75 - 121mm

WG/75 - 72mm

WG/38 - 50mm

Fixing Options

5mm

Enlarged

detail

Damper

drive

position

(electric

actuator

illustrated)

6

7

Mistrale Model BIntake unit with Heating Coil

Model B is a further variation on Model A and is primarily

intended for installation above the floor level at low or mid

room heights whilst still providing for optimum air flow and

comfort conditions.

Cooling outside air will be drawn through the assembly

with the warmer air ventilating through higher level wall

grille and damper assemblies out into the stack. Units are

fitted with a coil to allow for initial heating or cooling of the

air before entering the room.

A typical arrangement (as illustration) comprises

• External Louvre - Standard high efficiency weather

louvre with choice of flange, channel or window

beading fixing frame options.


or Motor control.


• Decorative Fascia Grille - Standard routed or perforated

face pattern fascia panel or any of our other grille

designs such as eggcrate or linear bar type grille.

Size Range

Effective damper size (internal blade area).

Width - 300 up to 2000 in 100mm increments

Height - 206 up to1006 in 100mm increments


Damper width +260mm

Damper height +110mm

External LouvreBoth the external louvre and the fascia grille

finished to standard BS/RAL colour.

Louvre Glazing

Bead


Fixing Options

Dim ‘A’ WG/100 - 121mm

WH/75 - 121mm

WG/75 - 72mm

WG/38 - 50mm


Mistrale Model CConcealed Intake unit with Heating Coil

Model C is an alternative to the popular Model A and is

primarily intended as a supply/intake unit for installation

above the ceiling or below floor level. Cooling outside air

will be drawn through the assembly and delivered to the

occupied zone via standard ceiling or floor diffusers.

Although slightly less efficient in terms of the air

movement path this model does have the distinct

advantage of having more space (due to the physical

location) which also then allows installation of silencers to

attenuate incoming noise. This potentially makes the unit

a better selection in more urban city environments where

noise ingress might be an issue.

Standard arrangement (as illustration) comprises

• External Louvre - Standard high efficiency

weather louvre with choice of flange, or channel

fixing frame options.


or Motor control.


• Acoustic Silencer - Optional silencer in single

or double bank assembly.

Size Range





Damper width +260mm


External LouvreExternal louvre finished to standard BS/RAL colours.

Louvre Glazing

Bead


Fixing Options

Dim ‘A’ WG/100 - 121mm

WH/75 - 121mm

WG/75 - 72mm

WG/38 - 50mm

8

9

Model DIntake unit without Heating Coil

Similar to Model C, Model D is primarily intended for

installation above the floor level at low or mid room height

and provides for optimum air flow and comfort conditions.

Cooling outside air will be drawn through the assembly

with the warmer air ventilating through higher level wall

grille and damper assemblies into the stack. In Model D

however units are designed for installation where an

independent heating system is employed and so are not

fitted with integral heating/cooling coils.





• Insulated Volume Control Damper - Manual or Motor

control.

• Decorative Fascia Grille - Numerous type of fascia

grilles can be fitted.

Size Range





Damper width +260mm


External LouvreBoth the external louvre and the fascia grille

finished to standard BS/RAL colours.

Louvre glazing

bead


Fixing Options

Dim ‘A’ WG/100 - 121mm

WH/75 - 121mm

WG/75 - 72mm

WG/38 - 50mm


Model EExhaust unit without Heating Coil

Model E is primarily intended for installation at high wall or

stack level to provide an external outlet for the warm stale

exhaust air. Depending on the functional area units may

require an insulated damper or non insulated blade

damper. With no air tempering requirements in these

areas no heating/cooling coil options are available.

A typical arrangement (as illustration) comprises




• Volume Control Damper - Volume control damper

may be insulated or un-insulated and with Manual

or Motor control.

Size Range


Width - 300 up to 2000 in 100mm increments.

Height - 206 up to1006 in 100mm increments.


Damper width +200mm


External LouvreBoth the external louvre and the fascia

grille finished to standard BS/RAL colours.

Louvre Glazing

Bead


Fixing Options

Dim ‘A’ WG/100 - 121mm

WH/75 - 121mm

WG/75 - 72mm

WG/38 - 50mm

10

11

Model FTransfer Exhaust unit without Heating Coil

Model F is primarily intended for installation at high room

level for exhaust or transfer application. Stale warmer air

from the room will be drawn through the assembly into the

stack. With no air tempering requirements units are not

fitted with heating coils.


• Volume Control Damper - Insulated or non insulated

and with either Manual or Motorised control

• Decorative Fascia Grille - Numerous type of fascia

grilles can be fitted to one or both damper sides.

Size Range





Damper width +260mm


External LouvreFascia grille finished to standard BS/RAL colours.

Mistrale Natural VentilationComponents Depending on the ventilation strategy and the preferred

location the installation may require a mix and match of

various standard Mistrale components

Intake Louvre

Gilberts intake louvres provide a high weather efficiency

design with only a standard single louvre bank arrangement.

This slender robust but weather efficient and patented

design offers a much lower pressure resistance than

conventional double bank weather designs. This allows us

to use smaller louvre areas for any given air requirement

or in effect provide more air, size for size, as compared to

competitive designs ensuring maximum design cost

efficiency. Structurally strong they can be fitted in to

either window openings or walls.

Air Volume Control Damper

Close control is one of the key factors for an effective

natural ventilation system with the ability to regulate airflows

accurately to meet occupancy levels and temperature

requirements vital. The patented Gilberts volume control

damper is a unique design that is fully adjustable ranging

from full open to full closed. When closed the damper has

an extremely low leakage rate that prevents draughts and

inefficiencies.

The casing is manufactured from low conductivity material

which prevents any cold bridge effect allowing total isolation

from internal to external areas. Furthermore the damper

comprises a double insulated blade arrangement which

means that the damper has a very low ‘U’ value (when

closed) of 1.6 w/m2 ˚C, which is as good as a sealed double

glazed window unit This prevents wasteful energy losses

or gains. The insulation also provides a secondary acoustic

reduction effect.


Heating coils add a wide degree of flexibility to the system

providing not only for tempering of the air but also for some

heating capacity to be employed within the design. When

used to support heating the system air movement is actually

accelerated, resulting in a faster and more efficient heating

process as compared to pure radiator based systems alone.

Alternatively cooling coils or dual purpose heating/cooling

coils can also be fitted to allow full control over air intake

temperatures.

12

13

Performance Assured

Specific designs will use a combination of some or all

of these components along with a bespoke controls

strategy using room temperature and/or CO2 sensors

to deliver comfort conditions. Incorporated in 1960

Gilberts have been meeting the challenges of air

distribution for nearly 50 years and have all the tools,

techniques and expertise available to make your

project a success. All of our products are designed

and tested in our own air movement laboratory and

supported with airflow CFD modelling

Fascia Grilles

Gilberts manufacture a wide variety of fascia grilles

and diffusers for floor wall or ceiling mounting.

With a wide range of both standard and bespoke tested

designs we can provide grille design solutions to meet

the requirements of the most demanding projects.

Decoratively designed punched panels can also be used

on internal faces which can be fitted with insulation to

maintain a low surface temperature where required.

Intake/Exhaust Penthouse Turret

Louvre

The Gilberts intake/exhaust turret can be specifically

manufactured in a wide variety of configurations to

suit the system design parameters. The turrets can

be designed to suit wind driven systems or stack effect

with internal partitions and dampers providing for full

and accurate air movement control.

14

Gilberts Natural Ventilation intake louvres provide a high

weather efficiency design with only a standard single louvre

bank arrangement. Under driving wind and rain conventional

single bank louvres will allow some degree of water ingress.

With motorised dampers (and possibly coils) behind the louvre

this is undesirable and for this reason Gilberts Natural

Ventilation louvres are all of a high efficiency design as

standard.

Our slender weather efficient, patented louvre design is not only

narrow but also offers a much lower pressure resistance than

conventional double bank high weather protection designs.

This allows us to use smaller louvre areas for any given air

requirement or, in effect, simply provide more air, size for size as

compared to competitive designs. A key benefit here is that this

reduces the size requirements not only for the louvre but also

for expensive associated components like dampers and

heating/cooling coils to ensure maximum design cost efficiency.

Manufactured from extruded aluminium our louvres are

structurally very strong and can be fitted into either the

window openings or into the walls.

All louvres are fitted with bird guard screens as standard

with insect screens and weather cills also optionally available.

A durable polyester powder finish to any BS/RAL colour also

allows architectural choice to blend or contrast with the building

structure as required

Intake Louvres

Dim

ensi

on o

ver F

lang

es =

Lis

t Hei

ght +

45 (+

1m

m)

_

List

Wid

th o

r Hei

ght _

10m

m

mm57hctiP

Stru

ctur

al O

peni

ng =

Lis

t Wid

th o

r Hei

ght

121mm

Type NV-WHF/75

- Flange Face Border

Type NV-WHC/75

- Channel Frame Border

Dim

ensi

on o

ver C

hann

el =

Lis

t Hei

ght _

10 ( +

1m

m)

_

m m 5 7 h c t i P

Stru

ctur

al O

peni

ng =

Lis

t Wid

th o

r Hei

ght

121mm

Efficiency Graph Water Repellent & Drainage FeaturesTesting in accordance with European Standard EN13030 for

weather louvre Performance shows our WH unit be 99.5%

effective in screening/exhaust applications and 99% effective

even with face velocities of up to 1m/sec (rated at class ‘A’).

The performance graphs below illustrate effectiveness under

differing weathering parameters.

All testing was conducted in accordance with European

Standard EN 13030 ie: simulated conditions of 13m/sec (30mph)

wind speed with heavy rain. Even at extremes of selection the

unit offers excellent weather protection.

Similarly the pressure loss graph clearly indicates the minimal

pressure losses incurred by the WH design. Performance at

this level ranks the units alongside the very best in performance

louvres.

All Natural Ventilation assemblies are normally provided as

standard with a high efficiency weather louvre on the outside.

These units have been classified to the current weather louvre

test standard reference BS EN 13030 and offer a high degree

of water protection.

If however a small amount of water does pass through the

weather louvre blades, provision has been built in to the Natural

Ventilation design which will cater for collection and the drainage

of this water back to the outside via the lower section of the

assembly.

This design is similar to the design used on some double glazed

units and prevents water lodging in any part of the assembly.

It is however recommended that the units are cleaned on a

regular basis with all drain channels checked.

15

E C N A T S I S E R W O L F R I A

LOU

VRE

PRES

SUR

E D

RO

P Pa

m R E P E T A R N O I T A L I T N E V 2 E R V U O L F O m ( A E R A E C A F 3 m / s / 2 )

M R E P E T A R N O I T A L I T N E V 2 AE R A E C A F E R V U O L m ( 3 m / s / 2 )

S T S E T L L A N I D E E P S D N I W s / m 3 1 ) A : E T O N m / m m 5 7 ) B 2 E C A F E R V U O L O T N O Y A R P S R E T A W

S T S E T L L A N I

0 5 0

0 6

0 7

0 8

0 9

0 0 1

5 . 0 0 . 1 5 . 1 0 . 2

EFFE

CTI

VEN

ESS

% Y C N E I C I F F E R E H T A E W

0 8 0 7 0 6 0 5 0 4

0 3

0 2

0 1

0 . 3 0 . 2 0 . 1 5 . 0

5

2

2 e l b a T 1 e l b a T

ing parameters.

v

c Pressure/Volume Graph Effectiveness/Volume Flow

Graph

16

Volume Control Damper

Controllability is one of the essential key factors for an effective

natural ventilation system with the ability to regulate airflows

accurately to meet occupancy levels and temperature

requirements very important.

The patented Gilberts volume control damper is a unique design

that is fully adjustable from full open to full closed. When closed

the damper has an extremely low leakage rate that prevents

all draughts and system inefficiencies.

The casing is manufactured from low conductivity material

which prevents any cold bridge effect allowing total isolation

from internal to external areas. Furthermore the damper

comprises a double insulated blade arrangement which means

that the damper has a very low u value (when closed) of 1.6

w/m2 °C, which is as good as a sealed double glazed unit

preventing wasteful energy heat loss or gain. The insulation

also provides a secondary acoustic reduction effect. For less

sensitive areas, such as for exhaust, damper units can also be

specified without insulation without affecting leakage rates

The damper will typically be motor actuator controlled but can

also be manually operated if required.

In order to establish the increase in resistance that will apply

as the damper closes a graph showing pressure drop against

percentage open is detailed on page 17.

Current Building Regulation Requirement

Graph No.2 illustrates current building regulations maximum

leakage rate of 10m3/H/m2 and the actual leakage rate of a 1m2

damper.

The current damper design is approximately 40% below these

regulation requirements.

Casing Leakage Rating

Testing was conducted in accordance with BS/EN 1751 in order

to establish the casing leakage rate for a 1m2 damper. Following

these tests it was established that the unit conformed with Class

C which is also equivalent to Ductwork DW 144 specifications

Torque Rating

Tests were conducted on a 1m2 damper to establish the drive

torque requirement under operating conditions.

It was confirmed that 4 Nm was required to operate the

damper rising to 12 Nm to compress the seals for total closure.

Minimum recommended motor torque for this size of

unit = 20nm. For reduced damper sizes the following

would be recommended:- 2Nm reduction for every

100 mm reduction in damper height.

Pressure Leakage

In order to meet current building regulations graph details

are provided to illustrate the air leakage rates against various

pressure differentials (Graph Ref. 2)

The data has been derived from a 1 m2 damper tested in

accordance with BS EN 1751 and indicates the maximum

leakage now acceptable under current building regulations

against actual leakage rates at 50 Pa differential pressure.

Manual Control Motor ControlDamper Drive Options

Ref 1 - Manual Handle Operation

Ref 2 - Manual Teleflex Operation

Ref 3 - (3 Point) SM24A Actuator AC 24v/DC 24v

Ref 4 - (3 Point) SM24A-S Actuator AC 24v/DC 24v

Ref 5 - (3 Point) SM230A Actuator AC 100~240v

Ref 6- (3 Point)SM230A-S Actuator AC 100v/DC 240v

Ref 7 - (Modulating) SM24A-SR Actuator AC 24v/DC 24v

Ref 8 - (Modulating) SM24A-M Actuator AC 24v/DC 24v

Ref 9 - (Modulating) SM230A-SR Actuator AC 100~240v

17

Unit make-up Air space

6 10 12 16 20

4 mm/air 4 mm 3.18 2.87 2.78 2.68 2.67

4 mm/argon/4 mm 2.93 2.69 2.62 2.56 2.55

4 mm/air/4 mm k 2.59 2.07 1.91 1.73 1.70

4 mm/argon/4 mm k 2.18 1.73 1.60 1.5 1.48

4 mm/air/4 mm/air/4 mm 2.25 1.95 1.87 1.78 1.77

‘U’ values in W/m2K for vertical glazing subject to normal

exposure conditions according to BS 6993 Part 1

Thermal InsulationThermal transmittance testing was carried out in accordance

with the requirements laid down in BS EN 1751 to determine

the amount of heat that would be transferred through a 1 m2

damper assembly. Testing was carried out with the blades

insulated and also without insulation with the following results:-

Mill finish damper assembly after a minimum test period of

4 hours.

‘U’ value (Wm2/K) = 1.99

With damper blades insulated on both sides with 6.0 mm

of pyrosorb insulation material.

‘U’ value (Wm2/K) = 1.52

This compares favourably with values for a typical double

glazed panel.

0.01

0.1

1.0

10

2

3

4

5 6 7 8 9

2

3

4

6 5

7 8 9

3

2

4

5 6 7

9 8

0.1

10

100

1000

2

3

4

5 6 7 8 9

2

3

4

6 5

7 8 9

3

2

4

5 6 7

9 8

1 100 1000 1010 0.1 4 3 2 9 8 7 6 5 4 3 2 9 8 7 6 5 7 2 6 5 4 3 9 8 7 2 6 5 4 3 9 8

Volume L/S/m²

Pre

ssur

e (P

a) m

²

Volume L/S/m²

Pre

ssur

e (P

a) m

²

Full open

75% open

Act

ual l

eaka

ge a

t 50

PA

1.7 l/s @ 50Pa = 6.1m3/H/m2 2.77 l/s = 10m3/H/m2

Max

Allo

wed

leak

age

at 5

0 PA

25% open

50% open

Pressure Drop / Volume Graph (based on 1m2 High efficiency damper)

Open (Ref. 1 Various open positions) Full Closed (Ref. 2 Leakage)

Gra

ph 1

Gra

ph 2


The addition of a heating coil allows an extra degree of

control to your natural ventilation system.

Although we have a year round ventilation requirement

there are many days when outside air temperatures may

simply be too cold for direct input. In these instance in-line

heating coils can be used to temper the incoming air

to allow continuous ventilation rates without compromising

temperature control. Heating coils also add a wider degree

of flexibility to the system allowing an amount of space

space heating to be employed within the overall Ventilation

design. When used to support the heating system, air

movement actually results in a faster and more efficient

heating process as compared to pure radiator based

systems alone.

Type VN-H - Heating Coil

Type VN-HC - Combined Heating and Cooling Coil

A dual 4 pipe combined heating and cooling system is

also optionally available to provide summer cooling should

a suitable supply of chilled water be available. Since the

units require relatively high chilled water temperatures, in

order to avoid supply air condensing on the coil, they are

particularly suitable for including in a chilled ceiling water

circuit.

Coil Connections

The heating coils terminate with industry standard 15mm

copper connections. If combined heating/cooling coils are

fitted then separate flow and return connections are

provided for both the heating and cooling sections.

Coil Capacities

Heating and cooling capacities can be calculated

from the graphs on page 19.

Overall Coil Width = Effective Damper Size 75mm

Overall Coil Width = Effective Damper Size 75mm

Ove

rall

Coi

l Hei

ght =

Effe

ctiv

e D

ampe

r Siz

eO

vera

ll C

oil H

eigh

t = E

ffect

ive

Dam

per S

ize

Combined Heating and Cooling Coil

Heating Coil (only)

18

19

0 0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

1 2 3 4 Duty (kW)

Water flowrate against temperature drop (heating)

Wat

er fl

owra

te (l

itres

/s)

Hea

t out

put (

kW)

Coo

ling

outp

ut (k

W)

5 6 7 8 9 10 11 12

5˚C 10˚C 15˚C 20˚C 25˚C

Heat output against temperature difference

0

1

2

3

4

5

6

7

8

9

10

Mean water - outside air temperature (°C)

Cooling output against temperature difference

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Outside air - mean water temperature (°C)

per m2 coil face

per m2 coil face

0

0.05

0.1

0.15

0 0.5 1 1.5 2 2.5 3

2˚C

0.2

0.25

0.3

0.35

Duty (kW)

Water flowrate against water temperature rise (cooling)

Wat

er fl

owra

te (l

itres

/s)

0

0

5

10

15

20

25

30

35

40

10

20

0.30

0

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

0.1 0.2 0.3 0.4 0.5 0.6

40

50

60

70

Water flowrate (litres/s)

Water flowrate (litres/s)

Water pressure drop against flowrate (heating)

Water pressure drop against flowrate (cooling)

Wat

er p

ress

ure

drop

(kP

a)

Wat

er p

ress

ure

drop

(kP

a)

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Face velocity (m/s)

Coil airside pressure drop

pres

sure

dro

p (P

a)

4˚C 6˚C 8˚C

Htg Coil Htg/Clg coil

20

Fascia Grilles Gilberts manufacture a wide variety of fascia grilles and

diffusers for floor wall or ceiling mounting. With a wide

range of both standard and bespoke tested designs

we can provide grille design solutions to meet the

requirements of the most demanding projects.

Decoratively designed punched steel panels can be used

on internal faces of low level wall units and these can be

fitted with insulation to maintain a low surface temperature

where required. As standard we offer the routed face

panel (flat or curved), a fixed blade linear bar grille with

blades angled at 0, 15 or 40 degrees and an eggcrate

pattern.

All grilles are manufactured from aluminium or steel and

can be finished in a durable polyester powder finish to any

BS/RAL colour.

Type VN/RP-1

Type VN/KO

Type VN/SK

Type References

VN/RP-1 Curved Routed Panel (Model A)

VN/RP-2 Flat Routed Panel (Models B, C, D & F)

VN/RP-3 Perforated Face Panel (Models B, C, D & F)

VN/KO Bar Grille (Models B, C, D & F)

VN/K15 Bar Grille (Models B, C, D & F)

VN/K40 Bar Grille (Models B, C, D & F)

VN/SKO Bar Grille (Models B, C, D & F)

VN/GE Eggcrate Core Type (Models B, C, D & F)

Type VN/RP-1 Type VN/RP-3

Type VN/KO Type VN/GE

Type VN/RP-3

Type VN/GE

Roof Top Penthouse Louvre

The Gilberts intake/exhaust penthouse turret

can be manufactured in a wide variety of size

and shape configurations to suit the system

design or aesthetic parameters. The turrets

can be designed to suit wind driven systems

or stack effect with internal partitions and

dampers providing for full and accurate air

control. All penthouse units are of our

patented high weather efficiency design as

standard to eliminate weather ingress and

can be fitted on to both flat and pitched roofs.

Design styles are flexible with traditional

square designs most popular and with a

variety of roof top options. Special or

bespoke roof tops can also be included to

complement or contrast with your building

design.

A durable polyester powder finish to any

BS/RAL colour allows a free matching

architectural choice. Bird guards screens are

fitted to the rear as standard

with insect screens also optionally available.

21

22

Penthouse Turret Options

Type 1 - Exhaust Turret Terminal

The Type 1 exhaust turret provides an attractive and

efficient means for rooftop exhaust of natural ventilation

air. Warm air rising up through the building can be easily

vented through standard rooftop exhaust terminals.

Manufactured with high weather efficiency blades the units

are designed to provide maximum weather protection to

prevent problematic ingress of rain. Standard blade pitch

is 75mm with a steep 45 degree blade angle.

Units can also be provided with eliminator sections behind

the standard blade profile to offer increased water

protection at high wind velocities.

TYPE VNT/1 - Standard Terminal

TYPE VNT/2 - Terminal with eliminator

The table below provides dimensions and weights for both

types of assemblies..

Nominal

Width ‘W’

(internal duct

width)

400

600

800

1000

1200

1400

400

600

800

1000

1200

1400

Eliminator

N

N

N

N

N

N

Y

Y

Y

Y

Y

Y

Unit

VNT/1

VNT/2

Nominal

Length ‘L’

(internal duct

width)

400

600

800

1000

1200

1400

400

600

800

1000

1200

1400

Height ‘H’

(Standard)

467

568

670

847

949

1051

467

568

670

847

949

1044

Weight

(kg)

22

35

51

79

104

134

26

42

62

95

125

172

Number of

blades

3

4

5

7

8

9

3

4

5

7

8

10

Standard roof illustrated above

Section showing

internal

eliminator array

on Type VNT/2

Curb Type - B1

23

Type 3 - Exhaust Terminal with Mounting Sleeve

and Damper

The Type 3 exhaust turret provides a means for rooftop

exhaust of natural ventilation air and includes a purpose

factory built mounting sleeve and volume control damper.

The louvre enjoys the exact same specification as the

Type 2 Terminal.

Type 3 however is a fully self contained terminal that does

not rely on further ducting or separate volume control.

It includes a motorised volume control damper at the base

which allows the unit to fully open, close or modulate

as demand requires. The damper is mounted on the sleeve

outlet and can be linked in to the natural ventilation building

management system. The damper (see full details on page

16) is our patented fully insulated design which again

provides a full thermal barrier with a U value of 1.6w/m2˚C.

Standard fixing is via kerb mounting flange and bird guards

are also fitted as standard with insect screens optionally

available.

Type 2 - Exhaust Turret Terminal with

Mounting Sleeve

The Type 2 exhaust turret provides a means for rooftop

exhaust of natural ventilation air and includes a purpose

factory built mounting sleeve. The louvre features the exact

same specification as the Type 1 detailed on page 22.

For Type 2 however the additional duct sleeve provides a

safe effective means to fit the louvre to the roof structure

and also allows for convenient ducting off below the roof

level. The sleeve is available in both an insulated and non

insulated format. The insulated version is standard with the

sleeve design incorporating a phenolic thermal foam barrier

which prevents transfer of heat/cooling energy from inside

to outside. This thermal barrier has a U value of 1.6w/m2˚C.

Standard fixing is via a kerb mounting flange and bird

guard screens are also fitted as standard to the rear.

Insect screens are available on request

Curb Type - B4

24

Type 5 – Wind Driven Terminal with Air Distribution

Plenum

The Type 5 provides a wind powered terminal that features the

exact same specification as the Type 4 but also includes a 4 way

distribution plenum at the base.

The turret is fitted to the roof using our standard installation

sleeve with built in thermal barrier. This sleeve terminates with a

motorised volume control damper which allows the unit to fully

open, close or modulate as demand requires. The damper is

mounted on the sleeve outlet and can be linked in to the natural

ventilation building management system. The damper (see

details on page 16) is our patented fully insulated design which

again provides a full thermal barrier with a U value of 1.6w/m2˚C.

The 4 way plenum fitted at the base allows for fitting of a variety

air grilles and diffusers.

Type 4 – Wind Driven Terminal

As well as Natural Ventilation Exhaust turrets we are able

to offer a complete range of wind powered terminals. Wind

powered systems operate somewhat differently than stack

effect system and, as explained on page 2, they rely on the

wind driving cool fresh air down into the building with the

warmer air exhausting both through buoyancy and

incoming air pressure displacement. In order to create this

feature the turret is fitted with specialised splitters that

provide four separate air paths. Air is driven down into the

occupied zone through one or more of the airways and is

then exhausted through the remaining airways. The wind

direction will determine which airways are used at any

particular time.

The turret is fitted to the roof using our standard installation

sleeve with built in thermal barrier. This sleeve terminates

with a motorised volume control damper which allows the

unit to fully open, close or modulate as demand requires.

The damper is mounted on the sleeve outlet and can be

linked in to the natural ventilation building management

system. The damper (see details on page 16) is our

patented fully insulated design which provides a full thermal

barrier and a U value of 1.6w/m2˚C.

25

1

2

3

9 8 7 6 5 4 3 2

4

5 6 7 8 9

2

3

4

7 6 5 4 3 2 1 9 8 1

2

3

4

5 6 7 8

1 9

2

3

4

6 5

7 8 9

3

2

4

5

1

6 7

9 8

1000

100

100 1000

10

4 3 2 1 9 8 7 6 5

6 5

7 8 9 1

3

2

4

5

7 2 6 5 4 3 1 9 8

6 7

9 8

1

Volume L/S

Pre

ssur

e (P

a)

1

2

3

9 8 7 6 5 4 3 2

4

5 6 7 8 9

2

3

4

7 6 5 4 3 2 1 9 8 1

2

3

4

5 6 7 8

1 9

2

3

4

6 5

7 8 9

3

2

4

5

1

6 7

9 8

4 3 2 1 9 8 7 6 5

6 5

7 8 9 1

3

2

4

5

7 2 6 5 4 3 1 9 8

6 7

9 8

1

Volume L/S per Sq m

Pre

ssur

e (P

a)

100 1000

1000

100

10

Pressure Drop Volume Graphs

Blades at 45° Blades at 45° with eliminator

Airflow Diagrams

Intake or Exhaust Turret

Types 1, 2, & 3 Wind Driven Terminals Types 4 & 5

Sizing And Selection Charts

The following data has been obtained from actual

tests of penthouse turret assemblies.

Graphs A & B represent pressure drops associated

with various volume flow rates as taken from a

1 cubic metre area penthouse.

With four sides this equates to an active louvre face

area of 4 sq metres.

In order to establish the air flow rate that would give

the same pressure drop through a 1 sq metre face

area louvre therefore the volumes given would be

divided by a factor of 4.

Two different weather louvre designs are available.

The Type NVT/1 is our standard single bank design

and the Type NVT/2 is a single bank design with

additional rear eliminator channels. Whilst both of the

designs meet class A specification the Type NVT/2

offers the extra degree of weather ingress protection

that may be required for certain projects.

Natural flow of

air to and from

building

depending on

design

requirements

and temperature

differentials

Exhaust on

leeward side

Wind

pressure

Graph A Graph B

26

Penthouse LouvrePerformance DataThe following tabulated table provides comprehensive

sizing data for all of our standard size penthouse

turret louvre range.

Figures in the table are based upon air volume

and duct velocity variables and these can easily

be changed within a selection program to give

new data on alternative sizes where required.

Eliminator

N

N

N

N

N

N

Y

Y

Y

Y

Y

Y

Unit

VNT/1

VNT/2

Nom Size

(internal

duct size)

400

600

800

1000

1200

1400

400

600

800

1000

1200

1400

Nominal Height

(Blades x 75)

225

300

375

525

600

675

225

300

375

525

675

750

Theoretical

Blade

Requirement

3

4

5

7

8

9

3

4

5

7

8

9

Standard

Blade Qty’s

3

4

5

7

8

9

3

4

5

7

8

10

Modified

Blade

Qty

3

4

5

7

8

9

3

4

5

7

9

10

Over

Blade Size

765

965

1165

1365

1565

1765

765

965

1165

1365

1565

1765

Structural

Opening

(on plan)

532

732

932

1132

1332

1532

532

732

932

1132

1332

1532

Free

Area of

Duct

0.16

0.36

0.64

1.00

1.44

1.96

0.16

0.36

0.64

1.00

1.44

1.96

Geometric

Free Area

through

Louvre

0.19

0.39

0.64

1.14

1.56

2.05

0.19

0.39

0.64

1.14

1.76

2.28

Volume at

1m/s

through

Duct (l/s)

160

360

640

1000

1440

1960

160

360

640

1000

1440

1960

Active

Face Area

of Louvre

(m2)

0.57

1.03

1.60

2.61

3.48

4.47

0.57

1.03

1.60

2.61

3.85

4.91

l/s/m2 of

Louvre

(Face

Velocity)

279

350

400

384

414

438

279

350

400

384

374

400

LEGEND:

Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Standard order code

Eliminator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Two Alternatives, recommend Type 1 for wind catchers and Type 2 for stacks for water ingress reasons

Nominal Size (internal duct size) . . . . . . . . . . . . . .This will be the list size, the internal dimensions of the stack

Nominal Height (blades x 75+320) . . . . . . . . . . . . .The total height of the unit including lid and plinth from the top surface of a flat roof

Theoretical Blade Requirement . . . . . . . . . . . . . . .This is the quantity of blades required to get the louvre blade free area to equal or to the desired ratio over stack free area

Standard Blade Qty . . . . . . . . . . . . . . . . . . . . . . . .This is the quantity of blades proposed for the standard product, sized to give a coefficient of discharge above 0.5

Proposed Blade Qty . . . . . . . . . . . . . . . . . . . . . . . .This is the quantity of blades used to calculate the Heights/Pressures/areas/coefficients of discharge.

Over Blade Size . . . . . . . . . . . . . . . . . . . . . . . . . . .The overall size of the units

Structural Opening (on plan) . . . . . . . . . . . . . . . . .The size of the opening required in the roof skin

Free Area of Duct . . . . . . . . . . . . . . . . . . . . . . . . . .Stack internal width x internal length (footprint)

Geometric Free Area through Louvre . . . . . . . . . . .The total free area path through the four faces of the unit

Volume at 1m/s through Duct (l/s) . . . . . . . . . . . . .Volume flow rate through the louvre at 1m/s stack velocity (likely velocities may be 0.25 to 0.5

Active Face Area of Louvre (m_) . . . . . . . . . . . . . .The active area of the unit, 4 x blade pack height x width between internal blade end supports (if

l/s/m2 of Louvre . . . . . . . . . . . . . . . . . . . . . . . . . . .Volume passing through the louvre (at 1m/s) / Active face area -Relates to the pressure drop tests

Pressure Drop@ 1m/s . . . . . . . . . . . . . . . . . . . . . .Pressure drop on the Terminal unit with 1m/s coming out of the stack

Pressure Drop@ 'above' m/s . . . . . . . . . . . . . . . . .Pressure drop on the unit with the duct velocity setting in the square above the table (user settable)

Pressure Drop@ 'above' l/s . . . . . . . . . . . . . . . . . .Pressure drop on the unit with the air volume setting in the square above the table (user settable)

Terminal Coefficient of Discharge (or entry) . . . . . .Coefficient of discharge of a terminal unit -(open duct ~1, with terminal sized for 0.5 min, or 100% free area ratio min)

Louvre Coefficient of Discharge . . . . . . . . . . . . . . .Coefficient of discharge of a single louvre unit weight

Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Unit weight not including duct and skirt

Nominal Duct Length . . . . . . . . . . . . . . . . . . . . . . .Nominal length of duct for roof angles and thickness set in boxes above the table

To use as a selection calculator please contact Gilberts Technical Department

27

Unit

VNT/1

VNT/2

Pressure

Drop@

1m/s

0.58

0.92

1.20

1.10

1.28

1.44

0.86

1.35

1.76

1.62

1.54

1.76

Pressure

Drop@

above m/s

9.33

14.72

19.16

17.66

20.54

23.02

13.69

21.59

28.10

25.90

24.60

28.10

Pressure

Drop@

above m/s

364.50

113.60

46.77

17.66

9.91

5.99

534.60

166.62

68.60

25.90

11.87

7.31

Terminal

Coefficient

of

Discharge

0.712

0.628

0.578

0.593

0.564

0.542

0.642

0.555

0.505

0.520

0.530

0.505

Louvre

Coefficient

of

Discharge

0.283

0.283

0.283

0.283

0.283

0.283

0.234

0.234

0.234

0.234

0.234

0.234

Weight

22

35

51

79

104

134

26

42

62

95

125

172

Nominal

Duct

Length

1400

1600

1800

2000

2200

2400

1400

1600

1800

2000

2200

2400

28

Acoustic SilencerMistrale model Type C provides the facility to

include an acoustic silencer to reduce noise

migration from external sources. Although the

combination of louvres, dampers and coils on

other models does provide some degree of

noise reduction for more urban areas an extra

degree of noise reduction may be desirable.

The Mistrale model Type C is particularly suited

since it is designed to be installed either above

the ceiling or below the floor where the extra

depth required for a silencer is less critical.

Two silencer models are available with the

Type 1S just 220mm deep and the Type 2S

presenting at 420mm deep.

Noise reduction performance guidance for

various configurations including the silencer

model Type 1S is provided on page 29.

Effective damper width +200mm

Effective damper width +300mm22

0 de

pth

220 or 420 depth

Effe

ctiv

e da

mpe

r hei

ght

Effe

ctiv

e da

mpe

r hei

ght

29

Acoustic InformationExtensive acoustic testing has been carried out

in order to establish the noise reduction values

which can be reasonably expected from each

component of our Natural Ventilation assembly.

Whilst heating/cooling coils give limited

reductions both the weather louvres and

dampers do contribute to the overall noise

reduction index.

A slim 200mm deep acoustic silencer was

also tested with the other key components to

provide a higher performance acoustic option

if required.

The figures provided below illustrate the 1/3

octave db reductions in sound pressure levels

when measured in accordance with BS EN ISO

140-3:1995 (sound reduction index) and BS EN

20140-10 1992, ISO 140-10:1991 (elemental

normalised level difference).

Unit Area

1 m2

0.5 m2

0.25 m2

0.125 m2

63

3

6

9

12

125

4

7

10

13

250

6

9

12

15

500

9

12

15

18

1.0k

14

17

20

23

2.0k

20

23

26

29

4.0k

24

27

30

33

Rw

14

17

20

23

Dn,e,w

22

25

28

31

MEAN FREQUENCY (OCTAVE BANDS) Hz

SOUND REDUCTION INDEX FIGURES (dB) for WEATHER LOUVRE + OPENDAMPER (acoustically lined blades) +200 WIDE TUBULAR SILENCER

Unit Area

1 m2

0.5 m2

0.25 m2

0.125 m2

63

3

6

9

12

125

4

8

10

13

250

3

7

9

12

500

4

8

10

14

1.0k

7

11

14

17

2.0k

10

14

17

20

4.0k

14

18

19

26

Rw

8

12

15

20

Dn,e,w

16

19

22

25


Unit Area

1 m2

0.5 m2

0.25 m2

0.125 m2

63

3

6

9

12

125

4

7

10

13

250

3

6

9

12

500

4

7

10

13

1.0k

5

8

11

14

2.0k

6

9

12

15

4.0k

10

13

16

19

Rw

5

8

12

17

Dn,e,w

14

17

20

23


Unit Area

1 m2

63

12

125

12

250

12

500

22

1.0k

27

2.0k

32

4.0k

35

Rw

26

Dn,e,w

34


AS ABOVE WITH DAMPER HALF OPEN

AS ABOVE WITH DAMPER CLOSED

NoteIf RW figures have been

given on a reduced

opening area they have

been calculated back

to a 1m2 opening.

SOUND REDUCTION INDEX FIGURES (dB) forWEATHER LOUVRE + OPEN DAMPER (acoustically lined blades)

30

Mistrale Natural Ventilation Control

The Mistrale fresh air Natural Ventilation unit marks a new

era for room environmental controls. It greatly simplifies the

building infrastructure normally required with fan coil units

by removing the need for large air handling units and ducting

systems within the building. Fresh air is supplied directly to

each room space as required avoiding cross contamination

and providing a level of freshness ‘like opening a window’.

Mistrale has no fan. It is therefore quiet and energy efficient.

Mistrale units are available with the following control

options�

• Manual fresh air control with no heating or cooling

requirement.

• Fresh air control with free cooling.

• Fresh air control with free cooling and hot water heating

coil.

• Fresh air control with free cooling, chilled water cooling

and hot water heating.

Air quality can be maintained by fitting a room CO2 sensor

to any of the above options. This provides automatic fresh

air control. A humidity sensor can also be fitted to manage

condensation in bathrooms and wet areas.

The controls are mounted inside the ventilation unit and

manage the complex relationship between dampers,

actuators and temperature measurements.

An attractive LED wall control provides a simple intuitive

control for settings such as space temperature and fresh air

level. A 3 button 2 line LCD control panel is used to set up

the control parameters, set-points and options for a room or

local area. The LCD also displays system parameters and

fault conditions such as sensor fail or low temperature

conditions.

The room space temperature sensor and CO2 sensor are

mounted on the wall in a small brushed stainless steel

enclosure which matches the wall control plate and provides

durability.

The system extracts air at a high level using body heat and

temperature gradients within the space to drive the airflow.

Extract dampers are controlled directly from the unit.

Controllers in different room spaces can be linked by a

twisted pair network to control a common extract damper.

High limit sensor(ref.9)

Heat exchangers heating or cooling

TC02 Controller (ref.1)

water valve actuators (ref.7&8)

Low limit sensor (ref.10)

Fuse spur (ref.12)

Mistral LCD area control plate option (ref.2)

Mistral LED control plate (ref.3)

Extract damper (ref.6)

CO2 and temperature sensor (ref.4)

Mistral Computer control option

Damper actuator (ref.5)

Outside air sensor (ref.11)

Ref

Ref1

Ref2

Ref3

Ref4

Ref5

Ref6

Ref7

Ref8

Ref9

Ref10

Ref11

Ref12

Component description

TC02 controller din rail mount with transformer

TCB LCD panel display for area control

TCB LED panel display for room control

CO2 and temperature sensor unit

Damper Actuator

Damper Actuator

Water valve actuator

Water valve actuator

High limit sensor

Low limit sensor

Fresh air sensor

Fused spur 230 Vac

Positioned by

Gilberts

Client

Client

Client

Gilberts

Gilberts

Client

Client

Client

Client

Client

Client

Wiring Connection

Gilberts

Client to controller (Belden 8723)



Gilberts within unit

Gilberts within unit

Client to controller flying lead

Client to controller flying lead

Gilberts flying lead



Client power flex

31

Control Strategy

The system maintains space air at the requested temperature

set-point with closed loop PID control by monitoring a wall

mounted air temperature sensor.

To save energy the system utilises free heating or cooling

as required.

There are 4 modes of operation, 2 heating and 2 cooling...

• Free heating (if supply fresh air is warmer than inside

air temperature)

• Standard heating (if supply fresh air is cooler than inside

air temperature)

• Free cooling (if fresh air is cooler than inside air temperature)

• Standard cooling (if fresh air is warmer than inside

air temperature)

If the unit enters free heating or cooling mode the system will

stay in this mode until it has remained at 100% capacity for

5 minutes (default) without achieving set-point temperature.

Only after this period will it switch to using heating or cooling

energy.

The system offers four fresh air level settings. With manual fresh

air control the dampers are opened by fixed amounts

for each setting with automatic control the dampers maximum

opening is limited to the setting. These amounts are configurable

from the LCD display. For example setting 1 opens the dampers

to 25%, setting 2 to 50%, setting 3 to 75% and setting 4 to

100%. In automatic mode the damper position

is regulated according to the difference between actual

and requested temperature.

During free heating or cooling the fresh air level settings have

no effect as the dampers are modulated to control space

temperature.

Space set-point and fresh air level settings are controlled from

a wall mounted plate this has two buttons and 10 LEDs, 5 for

set-point and 5 for fresh air level. Set-point is selectable by

pressing the top button which cycles through the five settings

(LED colour in brackets), from left to right these are 17°C (blue),

19°C (blue), 21°C (green), 23°C (red), 25°C (red). Fresh air level

is indicated by 5 green LEDs as off, 1, 2, 3, and 4. These

settings are also available for the LCD unit.

The fresh air damper will close if the water coils are in danger

of freezing (outside air temperature below 2°C default). The

maximum opening position of the fresh air damper will be

limited to a fixed value (default 10%) under extreme low

outside temperature conditions (default below 10°C).

Under these conditions the fresh air dampers will not be

influenced by the CO2 sensor.

The CO2 level of the room air is monitored and at 950ppm

(CO2 hi default) the fresh air and extract dampers are opened by

approximately 3% more. Once triggered, for every 1 minute

period (default) that the CO2 level remains above 950ppm

(CO2 hi default) the dampers are opened by a further 3% until

fully open. For every 1 minute period (default) the CO2 level falls

below 900ppm (CO2 lo default) the dampers are closed by 3%

until back to its original position. The damper position is left

unchanged if the level remains between the CO2 hi

and CO2 lo limits.

During free cooling the fresh air temperature entering the room

is monitored and if it is 3°C less than the set-point temperature

is tempered with the heating coil. The cool air entering the room

will never be more than 3°C below the set-point. This avoids

a very cold layer of air building up at floor level.

A temperature sensor also monitors the low pressure hot water

system and only allows the damper to open if hot water is

available.

The surface temperature of the outlet grille can be optionally

monitored to limit the surface temperature to approximately

40°C.

A seven day time clock is available with two on/off settings per

day. At switch on time the default room set-point and fresh air

settings are automatically selected. During the off period the

unit can be manually turned on from the LED wall plate, after

two hours the unit will automatically switch off.

A night cooling feature is available during the summer months,

which allows cool air to enter the room space during the night

cooling the building infrastructure. This provides a level of free

cooling the following day.

Network Connection Network connection points can be Ethernet or RS485 type. Ethernet allows for connections to be made to an existing infrastructure. This may be a convenient option in larger buildings with well defined communication RS485 is ideal for the more industrial or smaller building. Network with Modbus protocol can be supplied. This allows for connection to main BMS.

Dumb slave units save the controller cost. The dumb slave unit must be wired to the nearest Master Mistrale Controller. All actuators and dampers will be driven directly by the master.

Intelligent slave units save the site wiring cost. The intelligent slave unit must be connected to the chosen Master nearest Master Mistrale Controller. All actuators and dampers will be driven directly by the Slave under control of the master.

Mistrale controller in unit

Wiring to controller

Wiring to controller

Local LON connection Belden 8723

Local LON connection Belden 8723

Group option shows Mistrale and 2 dumb slaves

Group option shows Mistrale and 1 dumb slave

Typical local Mistrale unit network 1 to 32 units

Typical local Mistrale unit network 1 to 32 units

Mistrale LCD area control plate option

Mistrale LCD area control plate option

Internet connection

Mistrale computer control option

RS485 Communications Belden 8723

RS485 Communications Belden 8723

Group option shows Mistrale and 1 intelligent slave

Group option shows Mistrale and 2 intelligent slaves

32

MISTRALE LCD display

The LCD unit may be used to provide a programmable interface to the Radiator

system for overall strategy and comfort control.

A switch on the LCD unit displays its module address for about 4 seconds.

Up to 8 LCD units can be connected to the LON cable, which can be up to

100m long. Each LCD unit must be given a different module address (0 to n).

To set the LCD module address hold down all three buttons for >10 seconds.

The unit will then display “module X”, press the right button to increase the module

address and the left button to decrease it.

Pressing the centre button selects the next menu item, which is the LCD backlight on

time, this can be between 1 and 25 seconds or OFF for always off and ON for always

on. Once set up just wait 10 seconds (without pressing a button) for the display to

return to normal and the new settings to be saved.

MODBUS

The TC02 unit supports the MODBUS RTU open network protocol. This allows

connection to any standard BMS, a PC based area control system or HID panel.

The hardware interface is half duplex RS485 (single twisted pair) and we normally

use a unit load driver chip with +/-60 volt line protection (LT1785CN8).

There are four screw terminal connections on the board these are RS485 B, RS485 A,

Shield In, and Shield Out. Either or both Shield In and Shield Out can be connected

to local ground via a jumper link. Normally only the Shield Out is linked to local ground.

The open protocol we use is MODBUS RTU at 19200 baud, no parity, 8 data bits,

and 1 stop bit. Each unit has a network address ID from 1 to 247 (8bit) settable

from the LCD interface.

The following MODBUS function codes are implemented�

Read Holding Registers (3)

Write Single Register (6)

Write Multiple registers (16)

LON LED HVAC plate Specification

The LON LED HVAC plate is design as a direct replacement for the standard

plastic wall units found on many HVAC systems.

The unit consist of user display board of approximately 95 x 60 mm fitted

with a stainless steel front plate. This board has ten LEDs and two push buttons for

controlling damper positions and set point. It is connected to the TC range of control

units via a twin twisted pair cable.

• Can be surface or flush mounted in a standard UK back-box or patress.

• Simple multi-drop digital twin twisted pair connection to controller.

• Powered via the twisted pair cable.

• Five temperature settings indicated by multi-colour LED’s

• Four Fresh Air damper positions and ‘closed’ indicated by five LED’s.

• Flashing LED’s indicate status information such as Damper or sensor fail.

• Engineering mode for full system status.

• Front plate Standard Supply is Brushed Stainless Steel (plates can be

customised to client requirements, e.g. brass or anodised aluminium.)

Control Display Options

System Performance

0.1 1.0 10 1

2

3

9 8 7 6 5 4 3 2

4

5 6 7 8

1 9

2

3

4

7 6 5 4 3 2 9 8 1

2

3

4

5 6 7 8

1 9

2

3

4

6 5

7 8 9 1

3

2

4

5

1

6 7

9 8

1 4 3 2 1 9 8 7 6 5

6 5

7 8 9 1

3

2

4

5

7 2 6 5 4 3 1 9 8

6 7

9 8

1

Face Velocity m/s

Pre

ssur

e (P

a)

Natural Ventilation Unit

Pressure Drop

33

Unit Size

1300 x 600

1300 x 400

1300 x 200

800 x 600

800 x 400

800 x 200

300 x 600

300 x 400

300 x 200

Effective

Area m2

0.78

0.52

0.26

0.48

0.32

0.16

0.18

0.12

0.06

Volume @

0.3 m/s

effective

face

velocity

0.234

0.158

0.078

0.144

0.096

0.048

0.053

0.036

0.018

Pressure

drop (Pa)

1.6

1.6

1.6

1.6

1.6

1.6

1.6

1.6

1.6

Ce

1.18

1.18

1.18

1.18

1.18

1.18

1.18

1.18

1.18

Example

Example

For the sizing of all unit types when incorporated into building

designs please refer to Gilberts selection software program

Alternative effective face velocities can be selected from the graph with

revised pressure details

Although pressure/volume graphs are provided

for individual components the information here

provides pressure loss details for a complete

natural ventilation assembly.

Data based on Model Type A for all standard

sizes.

34

Ordering SpecificationNatural Ventilation Unit

Product Reference (VN)

Damper + Coil + Silencer (depending on model selected)

External Louvre

Internal Grille

VN/100

VN/WH /Z /32 /BG /WC RAL 9060 75 1560 x 716

/A 1300 x 606 1560 x 716 /2A /IN /AF /RH /H /1S

Model A to F

Effective Damper Width x Height (mm)

Minimum structural opening size to suit Could be larger with louvre size specified

Drive System Manual or motorised Ref. 1 to 9

Structural Opening (Width x height mm)

Structural Opening (Width x height mm)

If Border Size Z Specified Above, Glass Thickness (mm)

Drive Handing RH or LH (As viewed from inside)

Coil Type /H or /HC (Models A, B or C only)

Silencer Type/1S or /2S (Model C only)

Product Reference VN/WH or WG

Border Style C, F or Z

Guard Options IS or BG

External Finish RAL Colours etc

Internal Finish RAL 9010 standard

Internal Grille Types (with low surface temp option Ref. LST)

Weather Cill (WC) Border Style “C” only

Louvre Blade Pitch 38, 75 or 100

Blade Insulation Required (IN)

Adjustable Feet (AF)

VN/RP-1 1560 x 716 RAL 9010

VN/RP-1 Curved Routed Panel (Model A) VN/RP-1/LST Curved Routed Panel (Model A) VN/RP-2 Flat Routed Panel (Models B, D & F) VN/RP-3 Flat Routed Panel (Models A, C, D & F) VN/RP-3/LST Flat Routed Panel (Models A, C, D & F) VN/KO Grille (Models B, D & F) VN/K15 Grille (Models B, D & F) VN/K40 Grille (Models B, D & F) VN/SKO Grille (Models B, D & F) VN/GE Grille (Models B, D & F)

35

Product ReferenceVNT-1 standardVNT-2 with eliminator

Penthouse Turret

VNT-1 /2 600 x 600 1000 B1 3

Type (1 to 5)

Nominal Size (width x height)

Insulated duct length400 to 2000mm in 200mm increments

Roof & curb details

Drive actuator options (3 to 9)(Types 3, 4 & 5)

NOTE: For detail of border types B2, B5 & B6 contact Gilberts Technical Department

Plinth (type 1 only) Illustrated B1Flat ‘C’ Bottom frame (type1 only) Not illustrated B2Flat slab type roof and curb Types 2, 3, 4, B4 illustratedPitch cladded roof (angle of slope) Max 45° Types 2, 3, 4, B5(12) not illustratedPitch tiled roof (angle of slope) Max 45° Types 2, 3, 4, B6(12) not illustrated

Ordering SpecificationPenthouse Terminals

Gilberts (Blackpool) Limited

Clifton Road, Blackpool FY4 4QT Telephone 01253 766911 Fax 01253 767941

Email: [email protected] Web: www.gilbertsblackpool.com

Gilberts (Blackpool) Ltd reserve the right to alter the specification without notice. For our latest product data please visit www.gilbertsblackpool.com

The information contained in this leaflet is correct at time of going to press © 2009.

Documents

PUBLICATION NATURAL VENTILATION SYSTEM … Gilberts Mistrale Natural ... Type 2 - Exhaust Turret Terminal with Mounting Sleeve ... position (electric actuator illustrated) 6. 7