BSET LOC 1-Space Heating.pdf

8/9/2019 BSET LOC 1-Space Heating.pdf

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LOC 1: SPACE HEATING


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Need of space and water heating

Systems of space heating

Plant and equipment

Selection criteria

Space and water heating installation:

Low, medium ad high pressure, hot water systems, steam, warm air, radiant tube

systems, gas and electric local appliances. Implication and impacts selecting different fuels and energy sources on buildings

and environment.

Integration of heating in terms of noise, loading and heat gains


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Space heating is the heating of a space, usually enclosed, such as a house or room.

A space heater keeps the air and surroundings at a comfortable temperature for

people or animals, or even plants in a greenhouse.

Space heating generally warms a small space, and is usually held in contrast with

central heating , which warms many connected spaces at once.

Space heating does not include water heating , unless it is used for hydronic

heating.


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equipment installations

good design criteria

easy installation by M&E specialist

Separation of services space


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The following is a list of some of the factors that influence thetype of heating system that may chosen:

Cost

Fuel or Heat Source

Safety

Type of Building

Comfort

Power Supply

Space

Vandalism

Security of Supply of Heat Source

Let Buildings

Environmental Issues District Heating

Outside Conditions

Fluctuating Heat Demand

Appearances

Industrial Waste Heat


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1. Cost

Installation cost - Pipes are cheaper than ducts.

Running cost - Oil, Coal or Gas or Economy 7 electricity or wood products.

Life Cycle costs - Reliable system, long working life e.g. Cast Iron boiler.

Maintenance costs - Coal as a fuel may be expensive to maintain. Other systemshave less maintenance requirement.

Gas burns cleaner than oil and there is less soot to clean out of a gas boiler andflue.

2. Fuel or Heat Source

There is a choice in most countries between;

Oil, Coal, LPG (Liquid Petroleum Gas), natural gas, Economy 7 electrical heating,Ordinary Rate electrical heating, Wood products.

In some countries peat, lignite or soft brown coal is available.

The economics of burning this on a large scale would have to be considered.

There are various grades of oil, some of the more viscous (heavier) oils are cheaperbut require specially heated burners and heated pipes.

Calculate the less expensive option.

3. Safety

Calculate the less expensive option.

Some open gas and coal fires and paraffin heaters have a poor safety record.

Ensure all apparatus is approved and meets standards and regulations.

Systems that use steam should be inspected annually to ensure that pressure vesselsare safe and safety valves function.


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4. Type of Building

There are many types of building encountered in building services, the following are a few

suggestions:

Large areas benefit from the quick warm-up of air heating.

Ventilation systems with ductwork require ceiling void space.

For Warehouse radiant heating may be a suitable option since the air temperature need not be

high.

Hospitals require clean environment; thus filtered air heating may be necessary, usually in a full air

conditioning system.

Museums and Archive Stores require constant control of room temperature and humidity - air-

conditioning may be necessary.

In some buildings it is difficult to run services through e.g. stone walls, solid concrete slabs,

therefore electrical heating may be used.

In buildings with large occupancy a ventilation system may be necessary to provide adequate freshair for occupants e.g. concert hall, auditoria.

In buildings with high heat gains air-conditioning may be necessary to maintain comfort levels.

Schools have limited wall space so underfloor heating or low temperature ceiling heating is

sometimes used.

In some buildings like nursery schools and nursing homes, if radiators are utilised, it is advisable

that low surface temperature radiators are used.

In wet areas like shower rooms and bathrooms underfloor heating has an advantage in that it keepsthe floor dry.

Some buildings like churches may be intermittently used so electrical heating may not completely

ruled out.

High temperature roof mounted quartz electric heaters have been used in this type of building.

Prestigious areas may have full comfort air conditioning to reflect the importance of the room e.g.

board room.


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5. Comfort

To maintain adequate comfort conditions a controllable heating system will benecessary e.g. automatic controls on oil or gas-fired system or electricalheating system.

A solid fuel system cannot be easily controlled.

Wood pellet boilers are automatically controlled in the same way as otherboilers.

A comfortable heating system may incorporate some radiant heating as well asconvective.

Radiant heating is not always achievable but radiators produce about 70%convective and 30% radiant heating.

It may be difficult to obtain comfort levels in an office if a purely radiantsystem is used such as radiant panels so a mixture of convective andradiantheating is desirable.

If noise levels in a room such as a Library are to be at a minimum then fanconvectors are not a good option and some other quieter form of heating isbetter such as radiators, underfloor heating, natural convectors or a radiantceiling.


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6. Power Supply

When using electrical heating there must be an adequate electricalpower supply.

For a large building or group of buildings this may mean a new orupgraded electrical sub-station has to be provided.

7. Space

Plant requirements; room for plant and equipment, storage space for

fuel. Some construction methods do not provide adequate space for large

plant e.g. a trussed roof space is awkward to use for services plant.

A basement plant room can be compromised if the area is prone toflooding.

An apartment or flat may not have sufficient room for water tanks orboiler.

An inner city building may have no space for fuel storage thereforeelectrical heating could be the option if natural gas in unavailable.


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8. Vandalism

Some systems do not stand up to abuse.

Keep walls clear of pipes in some buildings e.g. prisons, detention centres.

Use steel instead of copper pipework in exposed areas.

Some emitters are not robust e.g. economy 7 electrical heaters.

Heavy-duty radiators can be used e.g. cast iron.

Some types of steel panel radiators are suitable for flush fitting in a wall if a recess is provided.

Prison cells can be heated with surface mounted low-level pipes.

Temperature sensors should be protected.

9. Security of Supply of Heat Source

Some fuels at certain times may be liable to unsecured supply e.g. oil prices can fluctuate during aMiddle East crisis.

It may be advisable to have a dual fuel system so that burners can easily be changed over to burnthe cheaper or more readily available fuel.

Alternative sources of energy are not always secure e.g. the wind doesn't always blow on a windfarm.

The sun doesnt always shine if the system relies on solar panels.

A hybrid system is more secure or back-up boilers can be used.


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10. Let Buildings

Most landlords prefer the tenant to look after payment of their own heating bills.

Individual meters for gas or electricity in a block of flats means that the tenants are responsiblefor the payment of bills.

In a large office building with several tenants, economy 7 electrical or natural gas heating may beused otherwise it is difficult to divide up a wet heating system serving a whole building so thatsuitable payments can be made for heating.

Some heat meters are expensive and not always reliable.

Some billing arrangement needs to be in place to charge tenants for heating.

11. Environmental Issues

The products of combustion of oil, coal and gas pollute the atmosphere. Coal is probably the worst offender since carbon dioxide contributes to the greenhouse effect and

sulphur dioxide causes acid rain.

Smoke causes urban smog and soot and ash add to the problem.

Oil produces contaminants to a lesser extent and gas is probably the best of the three.

Using electricity is of little benefit because power stations burn fuel to produce electricity or usenuclear fusion or fission as a source of heat which has its own impact on the planet.

A totally 'green' source of heat may be wind power or wave power or solar energy if you live in anarea with plenty of sunshine.

Wood products such as pellets have zero Carbon emission since trees can be replanted to replacethis fuel source.

Wood pellets boilers use pellets from an on site storage facility.


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14. Fluctuating Heat Demand

In some buildings the demand for heat fluctuates widely throughout theday.

To meet this demand economically, a modular boiler system is a goodoption.

This means that the required number of boilers is automatically switchedon to meet the demand.

In some circumstances it is recommended that condensing boilers can beused to meet the base heating load and non-condensing boilers can beutilised to meet the peak loads.

Condensing boilers squeeze more energy out of the fuel by taking extraheat out of the flue gases with a heat exchanger, Efficiency can be 98%

15. Appearances

In some rooms or buildings the designer may require the heating system

to be totally hidden e.g. underfloor heating, heated ceiling or airheating.

In some buildings the designer may wish to make a feature of the heatingsystem or heat emitters e.g. warm air ductwork system painted a brightcolour in a swimming pool hall or sports hall, Victorian cast iron radiatorsin a period building.


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Most heating systems for buildings use hot water which is pumped through pipework from aboiler (or boilers) to heat emitters in the rooms.

This has proved to be cheaper than warm air heating because installing pipework is less

expensive than ductwork and more equipment is necessary in warm air heating which

increases installation costs.

It is possible to heat large spaces with warm air using fan convectors fed with hot water but

these have several disadvantages, one of which is they tend to be noisy when running at high

speed.

Radiators have proved to be the most common type of heat emitter for small to medium

sized spaces, although under floor heating systems are becoming more popular. Most radiators act more like natural convectors because of the extended finned surface

which is readily obtainable.


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i) Water heating

Common components of a central heating system using water-circulation include:

Gas supply lines (sometimes including a propane tank), oil tank and supply lines or

district heating supply lines

Boiler (or a heat exchanger for district heating) heats water in a closed-water system

Pump

circulates the water in the closed system

Radiators wall-mounted panels through which the heated water passes in order to

release heat into rooms

Engineers in the United Kingdom and in other parts of Europe commonly combine the

needs of room heating with hot-water heating and storage. These systems occur less

commonly in the USA. In this case, the heated water in a sealed system flows through

a heat exchanger in a hot-water tank or hot-water cylinder where it heats water from the

normal water supply before that water gets fed to hot-water outlets in the house. These

outlets may service hot-water taps or appliances such as washing machines ordishwashers.

Sealed water-circulating system

A sealed system provides a form of central heating in which the water used for

heating usually circulates independently of the building's normal water supply.

An expansion tank contains compressed gas, separated from the sealed-system

water by a diaphragm. This allows for normal variations of pressure in the system. A

safety valve allows water to escape from the system when pressure becomes toohigh, and a valve can open to replenish water from the normal water supply if the

pressure drops too low.

Sealed systems offer an alternative to open-vent systems, in which steam can

escape from the system, and gets replaced from the building's water supply via a

feed and central storage system.

Fig: Expansion tank


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Boilers

A boiler is the heating plant used to create hot water

or steam for hydronic baseboard, radiant heat orsteam radiator heating systems. Boilers can use a

variety of fuels including natural gas, propane, oil or

electricity.

Steam boilers are more complex than hot water

boilers and have special gauge glass, pressure

gauges, blow off valves and automatic feeds.

Hot water boilers can be small, compact, energy

efficient and low maintenance.


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ii) Electric and gas-fired heaters

Electric heating or resistance heating converts electricity directly to heat. Electric heat is

often more expensive than heat produced by combustion appliances like natural gas,

propane, and oil. Electric resistance heat can be provided by baseboard heaters, space

heaters, radiant heaters, furnaces, wall heaters, or thermal storage systems.

Electric heaters are usually part of a fan coil which is part of a central air conditioner. They

circulate heat by blowing air across the heating element which is supplied to the furnace

through return air ducts. Blowers in electric furnaces move air over one to five resistance

coils or elements which are usually rated at five kilowatts. The heating elements activate

one at a time to avoid overloading the electrical system. Overheating is prevented by a

safety switch called a limit controller or limit switch. This limit controller may shut the

furnace off if the blower fails or if something is blocking the air flow. The heated air is then

sent back through the home through supply ducts.

In larger commercial applications, central heating is provided through an air handler which

incorporates similar components as a furnace but on a larger scale.


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iii) Hydronic and steam systems

Hydronic heating systems are systems that circulate a medium for heating. Hydronic

radiant floor heating systems use a boiler or district heating to heat water and a pump to

circulate the hot water in plastic pipes installed in a concrete slab. The pipes, embedded

in the floor, carry heated water that conducts warmth to the surface of the floor where it

broadcasts heat energy to the room above.

Hydronic systems circulate hot water for heating. Steam heating systems are similar to

heating water systems, except steam is used as the heating medium instead of water.

Hydronic heating systems generally consist of a boiler or district heating heat exchanger,

hot water circulating pumps, distribution piping, and a fan coil unit or a radiator located in

the room or space. Steam heating systems are similar except no circulating pumps are

required.

Hydronic systems are closed loop: the same fluid is heated and then reheated.

Hydronic heating systems are also used with antifreeze solutions in ice and snow melt

systems for walkways, parking lots and streets. They are more commonly used in

commercial and whole house radiant floor heat projects, while electric radiant heat

systems are more commonly used in smaller "spot warming" applications.


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iv) Heat pumps

In mild climates a heat pump can be used to air condition the building during hot weather,

and to warm the building using heat extracted from outdoor air in cold weather. Air-source

heat pumps are generally uneconomic for outdoor temperatures much below freezing.

In colder climates, geothermal heat pumps can be used to extract heat from the ground.

For economy, these systems are designed for average low winter temperatures and use

supplemental heating for extreme low temperature conditions.

The advantage of the heat pump is that it reduces the purchased energy required for

building heating; often geothermal source systems also supply domestic hot water. Even in

places where fossil fuels provide most electricity, a geothermal system may offset

greenhouse gas production since most of the energy furnished for heating is supplied from

the environment, with only 1530% purchased.


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A) RADIATORS

Radiators do not strictly speaking 'radiate' all their heat into the space but up

to 80% may be convected, typically for a double panel radiator about 30% of

total heat output is radiated and 70% is emitted by convection.

Radiators are used in a wide variety of buildings to provide central heating inrooms.

These emitters are usually positioned at low level, typically under windows,

although other positions can be used.

Heat outputs vary up to around 3 kW.

A typical radiator height for a house is 600mm, but other sizes are used

depending on location.

Radiators can be described by various means but the type of material used inthe manufacture is the main method of distinction.

Six radiator types as listed below show various methods of manufacture and

style to suit different conditions.

{1} Steel Panel - Simple convoluted panel which may be single, double or more.

{2} Cast Iron - Column type.

{3} Aluminium - Extruded sections.

{4} Tubular - Using vertical and horizontal steel tubes.{5} Bathroom Radiator - Various shapes and materials some for drying towels.

{6} Low Surface Temperature - Usually steel.


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Steel Panel


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Aluminium Sectional

A selection of aluminium radiators are shown below.

Aluminium radiators are more expensive than steel panel but are light withhigh heat output for size.

The material used and production techniques ensure a clean smooth finish

but one of the problems with using aluminium is corrosion of the metal incontact with hot water which may have a small quantity of air absorbed in it.

An inhibitorcan be provided as a capsule inserted in the radiator duringinstallation or special additivescan be added to the water duringcommissioning of the system to overcome this problem.


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Tubular

In some types steel tubes are welded to top and bottom headers.

Shown in photograph above.

Decorative appearance, useful where tall, narrow radiators are required.

Easier to clean than steel panel.

The photo below shows a radiator with horizontal flat tubes.

Bathroom Radiator

Bathroom radiators are made in various materials and shapes, some are

also used to dry towels.


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Low Surface Temperature (LST)

Some manufacturers make low surface temperature (LST) radiators for usein hospitals, old peoples homes, nursery schools, andkindergartens.

These prevent injury if hot radiators are used in these areas.

One method of limiting the surface temperature of a radiator to about 45oC is

to cover the hot metal parts with an outer casing as shown below.


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Natural convectors rely on air movement over the heating element by naturalconvection and forced convectors use a fan or fans to assist the movement ofair.

Small convectors called kickspace heaters are sometimes used in domestic

kitchens or hallways.


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3. Industrial Warm Air Heaters

The type of unit illustrated below is used for space heatingand has the

advantage of being simple in both construction and operation.Hot gasesfroman oil (or gas) fired burner are directed over a heat exchanger and thenexhausted through a flue to outside.

Air is passed over the heat exchangerby a fan or fans and is subsequentlyheated to about 30oC to 40oC. The warm air is supplied into a space throughoutlet diffusers, which can direct the air where it is required and throw heatedair up to about 10 metres from the point of discharge.

These units are suitable for large areas, which require heating since largeamounts of heated air can be supplied. Warehouses,factories,workshopsand supermarketsuse this type of heating and outputs rangefrom 30kW to 400kW.


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These units are suitable for large areas, which require heating since largeamounts of heated air can be supplied. Warehouses,factories,workshopsand supermarketsuse this type of heating and outputs rangefrom 30kW to 400kW.

It may be advisable to provide a protective areaaround floor standing unitsso that it is not tampered with or machines such as forklift trucks dont causedamage.

In some areas it is best to position industrial warm air heaters at high level orat roof levelto avoid possible damage and to give uninterrupted floor space.The unit may be supported from or suspended from the roof structure with thenozzles arranged to blow warm air into the space below.

One disadvantage of these units is that they can be noisysince a fuel burnerand fan are incorporated in the casing.


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4. Unit Heaters

Unit heaters are very like fan convectors in operation in that they blow outwarm air from a heat exchanger. The heat exchanger uses steam or hot waterto heat air, which is forced over the tubes and fins by a powerful fan.

Since the steam or water temperature may be high e.g. over 100oC and the

fan may develop a high volume of air, the output is 10kW to 300kW.

Unit heaters may be used in factories, workshops and warehouses.

One advantage of this convective form of heating is that a relatively small unit

can produce a high heat output, but fan noise has to be considered


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The photograph below shows an all-electric unit heater, which obviates theneed for pipework but is more expensive to run than wet oil and gas firedsystems.


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5. Skirting Heating

This form of low levelconvective heating can be used in areas whereunobtrusive emitters are required.

Since the heat output per metre linear run is low then a substantial skirting

length is required in each room to offset heat losses.

The heat output is about 450 Wattsper metre.

The units consist of one or two finned tubesinside a casing, which emits slowmoving warm air through a linear outlet at the top.

One disadvantage is that efficiencyis reduced by dust collecting in the fins.

Skirting heating can be used as perimeterheating below glazing or forbackground heat in some areas.


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6. Trench Heating

This type of heating is useful for some areas where perimeter heating at floor

levelis required.

Trench heaters consist offinned tube elements which are fully or partially

recessed into a steel casing within a concrete floor.

A trench is required around the perimeterof the room into which the tubular

heater is installed.

This has been used successfully in airports where large areas of perimeter glass

require an up-current of warm air to cancel out heat losses.

Trench heaters do not take up wall space and require a floor grilleto withstand

foot traffic.

Some aluminium floor grilles can be rolled up for cleaning.


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2. Metal Radiant Strips


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2. Metal Radiant Strips

For workshops, strip heaters can be used when supplied with high or mediumtemperature hot water or steam.

The radiant strip shown below uses a single pipe, other systems use 2, 3 or 4pipes to increase the radiant heat output.

Strips may be up to 1 metre wide but usually are continuous throughout thelength of a factory or workshop.

They are also suitable for mounting between stacking rows in a warehouse.

To enhance the effectiveness of the system a finis added to increase the hotsurface area, in the diagram below the fin is a profiled aluminium plate that isclipped to the pipe.

Some high outputs can be achieved with radiant strips e.g. 3kW per metre at100oC.

The photo below shows two radiant strip heaters at high level in a factory.


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3. Metal Radiant Ceilings

This type of radiant heating system incorporates the whole ceiling.

One type uses a ceiling made from metal platesabove which are clippedpipes containing hot water.

The pipes heat the metal ceiling below which in turn heats the rooms byradiation.

Typical heat output is about 160 Watts per square metreof floor area.

To make the system work effectively, some insulation is added on top of thepipes, as shown below.

Radiant ceilings can be used in a wide variety of buildings such as: schoolsand offices.

The system is silent but requires careful temperature control to ensure acomfortable environment.

Some radiant ceilings are invisible from beneath as the photograph belowshows. This type uses ceiling tiles with pipes above.


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Underfloor Heaters

Underfloor heating is suitable in areas where wall spaceis not available forother emitters and where a warm floor is not a disadvantage.

In some cases underfloor heating cannot be used due to the nature of thefloor and the type of materials proposed.

One of the disadvantages is that it may take some time before the benefit isfelt in a room particularly if a concrete slab or other materials have a high

thermal capacitance.

This time lapse is called thermal lag.

One area where underfloor heating is useful is in showeror changing areas,where the floor feels comfortable to stand on and is kept dry.

Two types of underfloor heating system are detailed below, they are:

(1) Piped Underfloor Heating (Wet System)

(2) Electrical Underfloor Heating

D) UNDERFLOOR HEATERS

1. Piped Underfloor Heating


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1. Piped Underfloor Heating

This consists of 15-20mm bore plastic pipes, laid without joints at 150-450mmcentres.

The pipes can be laid above a solid concrete slab and within a graded floorscreednot less than about 75mm thick, or under a suspended timber floor.

Copper tube is sometimes used (soft copper pipe to BS 2871 Table Y) butmore often Polyethylene tubehaving outside diameters of 17mm and 20mm,with 2mm thick walls, in coil lengths of up to 120 metres is the preferredmaterial.

When fixing polyethylene tubemetal strips holding plastic clips are laid on thebase slab, at right angles to the coil line, to form a locating grid. Anemulsifying agent is added to the screed mix to improve contact with the coils.

A typical tube layout is shown below.


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A typical tube layout is shown below.

A section through a solid flooris shown below with pipe clips fixed to a gridand sand / cement screed covering.

It is generally accepted that a floor surface temperature of 24oCshould not be

exceeded where occupants are static, 27oC where they are able to moveabout and about 30oCin corridors and halls.

A variety of finishesmay be used over heated floors and almost all types ofhard material, marble, slate, stone, terrazzo and brick are suitable providedthat provision is made for expansion and that no cavities are left in the finishto impede heat transmission.

In the case of softer materials, wood blocks may be used if properlyseasoned, cork tiles are satisfactory and carpets can be used if not foam

backed.

2. Electrical Underfloor Heating


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g

Most electrical forms of Underfloor heating use off-peak electricityand aretherefore storage-heating systems.

An alternative direct system can be used were heating elements are laid on asolid floor with an output of around 150 W/m

2, laid close to the finished floor

surface with about 50mm of insulating material under the coil elements.

Such an arrangement is suitable for a building used intermittently and for shortperiods such as churches, etc.

Floor warming can be successfully carried out by using Economy 7 off-peakelectricity to heat elements in the floor.

There are three system designs as shown below:


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1. Electrical Tubular Heaters

These are steel or aluminium tubesusually round or oval in section as shownbelow.

They consist of an electrical heating element, which extends from end to endand is surrounded by air.

The surface temperature is about 80oC. A single tube at 50mm diameter hasan out put of about 180 Watts per metrelength and tubes may be mounted inbanks, one above the other, for higher outputs.

An electrical skirting heater with an output of 400 Wattsper metre run istypical of some installations requiring background or low level heating.

Tubular heaters are used in churches, under pews, in greenhouses,conservatoriesand foyers. They can be placed at the bottom of high windows

to prevent downdraughts of cold air or be set to prevent frostin greenhousesor conservatories.

E) ELECTRICAL HEATERS

2 St H t


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2. Storage Heaters

Electrical storage heaters store heat overnightin thermal material and releasethe heat the next day to heat a building.

One of the advantages of electrical storage heaters is that cheaper electricitycan be used at night to heat up thermal storage material from which heat isemitted later the next day.

In the U.K. this cheaper tariff is called Economy 7because it is available forseven hours during the night-time.

There are several methods of storage and several types of room electricalstorage heater, such as; storage radiators, storage fan heaters and warmedfloors or walls.

Heat energy can also be stored centrally in several devices such as warm airunits, dry-core boilers, wet-core boilers and thermal storage cylinders.

One of the advantages of using a central system of storage is it is possible toobtain better control of the heating system in a large building if for example awet-core boiler is used and conventional hot water controls are utilised.

NOTE: A wet core boiler uses electricity to heat water in a steel or cast iron boiler.An electric current is passed between electrodes through the water, which due to itsresistance, becomes heated.An electrode boiler is about 98% efficient.


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Domest ic Storage Heaters

Storage heaters or storage radiators comprise a number of sheathedelements enclosed within blocks of refectory materialor Feolite to form theheated core, which is surrounded by insulation.

The surface temperature of the casing reaches a maximum of about 80oCat

the end of the charging period and this reduces to about40oCduring thefollowing day. Output is both radiant and convective in almost equalproportions.

Heater ratings vary with different makes but are usually 1.7, 2.55and 3.4kW,the seemingly odd figures being related to rounded 7 hour chargeacceptances of 12,18 and 24kWh.

Storage heaters are used in houses, flats, apartments and officebuildings.

They have the disadvantage that the heat output during the day is not easilycontrolledand may not match the heat loss in a building for any given period.

Also the lower electricity tariff (Economy 7) may not work out to be cheaperthan oil or gas. See fuels section of the notes.


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3. High Temperature Heaters

There are several types of Electrical High Temperature Heater:

(1) Infra red heater

(2) Quartz lamp heater

(3) High temperature panel

3.1 Inf ra Red Heater

The electrical elements used are similar to those fitted to luminous fires but,for a given rating, are commonly longer as shown below, and arranged to

operate at about 900oC.

Wall or ceiling models of these are suitable for kitchensand bathrooms,ratings are up to 3 kW.


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3.2 Quartz Lamp Heater

The elements of this type of heater operate at about 2000oCand consist of atungsten wire coil sealed within a quartz tube containing gas and a suitable

halide

- rating of elements about 1.5kW.

Some quartz lamp heaters are shown below.

These are used in large spaceseither where the requirement is intermittent orwhere only local areas require spot heating.


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3.3 High Temperature Panels

These consist of either a vitreous enamelled metal plateor a ceramictilebehind which a resistance element is mounted within a casing.

Panels of this type operate at a temperature of about 250oC and have ratingsin the range 750 W to 2 kW; they are normally used inwashrooms in industrialsituations.


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Documents

BSET LOC 1-Space Heating.pdf