Central steam heating system report

CENTRAL STEAM HEATING SYSTEM

Presented by:

Maaz Khan REG # 234

Zavain Rehman REG # 236

Usman Pervez REG# 245

H.M Immad Tariq REG# 233

Awais Iqbal REG # 230

HP

By Group B

By Group B [CENTRAL STEAM HEATING SYSTEM]

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ABSTRACT

In this report we discuss thoroughly about the central heating system, it provides some

recommendation to upgrade and improve the efficiency of central heating system in

houses, For that first a basic view of the heat load and heat load calculation. Secondly

the perimeters used to overcome the heat losses which can effects the energy

efficiency of the heating system. Third case, we discuss about the boiler and the types

of boiler used normally and the basic importance of using them. In fourth case we

discuss bout the radiator used and there types. Heat load, radiator, boiler, pipes

calculation


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TABLE OF CONTENT

Abstract

Main Text:

CENTRAL HEATING SYSTEM 5

1. Introduction_______________________________________________________________________5

1.1 How central heating system works___________________________________________________5

SECTIONS:

2. HEAT LOAD 6

2.1 What is Heat Load______________________________________________________________6

2.2 Factors Affecting Comfort in winter______________________________________________6

2.3 Mathematical Calculation_______________________________________________________7

2.3.1 Calculation ________________________________________________________________9

2.3.1.1 Apartment#1 ___________________________________________________________9

2.3.1.2 Apartment#2___________________________________________________________11

2.4 Table____________________________________________________________________15

2.5 assumption_______________________________________________________________15

3. INSULATION OF WALLS/ROOF/BOILER AND CONNECTING PIPES 16

3. What is Insulation_________________________________________________________________ 16

3.1 Types of Insulation______________________________________________________________17

3.1.1 Insulation Used________________________________________________________________17

3.2 table___________________________________________________________________________17

4. BOILER SELECTION

4.1 What is Boiler_____________________________________________________________________18

4.2 Types of Boiler___________________________________________________________________18

4.3 Selection of Boiler________________________________________________________________18

4.3.1 Fire tube boiler_______________________________________________________________18


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4.3.2 Our boiler specification __________________________________________________18

4.3.3 Types of Fuel Used in Boiler_______________________________________________19

4.3.4 Benefits are ____________________________________________________________19

4.3.5 Combustion energy______________________________________________________19

4.4 Boiler Losses and Measure of Efficiency__________________________________________20

4.5 Boiler Accessories___________________________________________________________ 21_

4.6 Calculations__________________________________________________________________22

5 T-S DIAGRAM 23

6 PLUMBING 24

6 What is Plumbing__________________________________________________________________24

6.1. Types of Piping_______________________________________________________________24

6.1.1 One pipe ___________________________________________________________________24

6.1.2 Two pipe ___________________________________________________________________24

6.2 Selection of Piping______________________________________________________________25

6.3 Steam Mains for gravity flow______________________________________________________25

7 RADIATOR SELECTION 26

7.1 What is Radiator_______________________________________________________________26

7.2 Types of Radiator______________________________________________________________26

7.3 Working ______________________________________________________________________29

7.4 Material _____________________________________________________________________29

7.5 Radiator selection_____________________________________________________________29

7.5.1 Material selection _________________________________________________________29

7.6 Sizing _______________________________________________________________________30

7.6.1 for apartment #2, 3, ______________________________________________________30

7.6.2 for apartment # 1_________________________________________________________30

8 BIOGRAPHY AND REFERENCE 31


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CENTRAL HEATING SYSTEM

1 INTRODUCTION:

A central heating system provides warmth to the whole interior of a building (or portion of a building)

from one point to multiple rooms. When combined with other systems in order to control the

building climate, the whole system may be an HVAC (heating, ventilation and air conditioning) system. Central Heating is a heating system in which air or water is heated at a central point and sent through the

whole interior of a building via vents or pipes and radiators to provide warmth in multiple rooms or parts

of a building.

Central heat sources can be boilers for oil, gas, biomass or solar heating systems. Depending on the size

of the building and available energy sources, a central heating solution might have multiple shapes.

1.1 HOW CENTRA L HEA TING SYSTEM WORKS

Central heating system as a continuous circuit moving steam out from the boiler, through all the radiators in

turn and then back again to pick up more heat The water is permanently sealed inside the system (unless it's

drained for maintenance); the same water circulates around your home every single day.

1. Natural gas enters your home from a pipe in the street. All the heat that will warm up your home is

stored, in chemical form, inside the gas.

2. The boiler burns the gas to make hot jets that play on a copper pipe

containing water. The copper pipe bends back and forth several

times through the gas jets so it picks up the maximum amount of

heat (in other words, the pipe works as a heat exchanger). The heat

from the gas is transferred to the water.

3. An electric pump pushes the heated water through the system.

4. The water flows around a closed loop inside each radiator, entering

at one side and leaving at the other. Because each radiator is giving

off heat, the water is cooler when it leaves a radiator than it is

when it enters. After it's passed through all the radiators, the water

has cooled down significantly and has to return to the boiler to pick

up more heat. You can see the water is really just a heat-

transporting device that picks up heat from the gas in the boiler

and drops some of it off at each radiator in turn.

5. The pump is powerful enough to push the water upstairs through


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the radiators there.

6. A thermostat mounted in one room monitors the temperature and switches the boiler off when it's hot

enough, switching the boiler back on again when the room gets too cold.

7. Waste gases from the boiler leave through a small smokestack called a flue and disperse in the air.

2 HEAT LOAD:

2.1 WHA T IS HEA T LOA D?

Heat load (including heat loss, or

heat gain) is the term for the amount of heating (heat loss) or cooling (heat gain) needed to maintain desired temperature

and humidity in controlled air (e.g., in a structure). Regardless of how well-insulated and sealed a building is, buildings gain heat from warm air or sunlight or lose heat to cold air and by radiation. Engineers use heat load calculations to determine the HVAC needs of the space

being cooled or heated.

2.2 FACTORS A FFECTING COMFORT IN WINTER

1. TEMPERATURE difference between the inside and outside of the building is the primary cause

of heat loss in the winter months. The greater this difference, the higher the rate of heat loss.

Since most buildings are controlled to a constant inside temperature by the occupants, higher

heat loss occurs when it is colder outside.

2. WIND is the second greatest source of heat loss during the winter. High winds can occur on

the cold nights and when they do, heat loss can be higher because of air scrubbing the outside of

the space covering. Winds can also force their way through cracks in the structure, causing

infiltration and drafts. In fact, up to one-third of the annual heating energy goes to heat this

moving infiltration air many times each winter day.

3. HUMIDITY levels can also affect the comfort within a structure. Very low humidity levels (less

than 20% relative humidity) cause scratchy throats and dry noses in most people.


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4. RADIATION sources can also affect comfort in a structure. The sun shining through a window will make a room very comfortable in winter; that same sun could make it unbearable in summer. Walls and windows also release and absorb radiation. A Trobe wall heated by the sun will keep a

room feeling warm with an air temperature less than 60°F. A large expanse of cold glass windows can also make a room feel chilly

2.3 MA THEMA TICAL CALCULA TION

The heat loss is divided into two groups:

1) The conductive heat losses through the building walls, floor, ceiling, glass, or other surfaces,

2) The convective infiltration losses through cracks and openings, or heat required to warm

outdoor air used for ventilation.

We neglect the infiltration and ventilation losses across the walls of apartments.

Q = A * U * (Ti – To)

Where

Q = Total hourly rate of heat loss through walls, roof, glass, etc in

Btu/hr

U = Overall heat-transfer coefficient of walls, roof, ceiling, floor, or

glass in Btu/hr ft2 F

A = Net area of walls, roof, ceiling, floor, or glass in ft2

Ti = Inside design temperature in °F

To = Outside design temperature in °F


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Heat loads of the Apartments is equal to Heat load across wall + Across Windows+ across

Roof Ceiling + Across Floor

Resistivity value of different materials used is as follows:

U=𝟏

𝑹𝟏+𝑹𝟐+𝑹𝟑

U=0.102

R(brick) per

inch

R (gypsum) per

5/8 inch

R(Cellulose) per inch

0.2 0.45 3

9 * 0.2 = 1.8 2.5*3=7.5


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2.3.1 CALCULATION

2.3.1.1 APARTMENT # 1

Bedroom # 2

Walls:

A= 188 ft sq

U= 0.102

∆T= 56.7

U= 188 * 57.6 * 0.102

Q=1104.5 Btu/hr

Window:

A=16 ft sq Double Pane with 1/4" air space R=1.69 width= 0.5”

R=1.69

U= 0.5

Q=0.5*57.6*16= 460 BTU/hr

Q=920 Btu.hr (for 2 windows)

Roof:

A=120 ft sq

R=7.05 U=0.1233

Polyutheren 1” 6.25


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Q= 120 * 57.6 * 0.1233

Q=967.68 Btu/hr

Total Room 2

Q= 2991.68 Btu/hr

BEDROOM #1

Walls

Q=0.102*57.6*204 =1198.5 Btu/hr

Windows:

Q= 460 Btu/hr

Roof:

Q= 0.14*57.6*120=967.6 Btu/hr

Total Room # 1

Q= 2627 Btu/hr

TV ROOM:

Walls

A=344 ft sq

Q= 344*0.102*57.6=2021.1Btu/hr

Windows:

Q=460 Btu/hr

Roof:

Q=0.14*57.6*186=1500 BTU/hr


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Total

Q= 3981 BTU/hr

TOTAL APT # 1

Q= 9600 BTU/hr

2.3.1.2 APARTMENT # 2

Bedroom 2

For the wall which are exposed to outside environment.

Ti= 89.6 F

To =32 F

U= 1/R (where R is the resistance)

Walls:

R(brick) per inch R (gypsum) per 5/8 inch R(Cellulose) per inch

0.2 0.45 3

so for wall R= 9.75 ( 9” brick wall) + ( 2.5” cellulose)+(5/8” gypsum)

U=0.102

Area = 213 feet sq

∆T= 57.6 F

Q= U* ∆ T * A


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Q= 0.102*57.6*213 = 1226.88 BTU/hr

WINDOWS:

A=16 ft sq Double Pane with 1/4" air space R=1.69 width= 0.5”

R=1.69

U= 0.5

Q=0.5*57.6*16= 460 BTU/hr

For 2 windows Q= 920 BTU/hr

ROOF/FLOOR:

A=151.2 ft sq

R=7.05 U=0.1233

Polyutheren 1” 6.25

R= 0.80 4” concrete

Q=151.2*57.6*0.14

=1235.3 BTU/hr

TOTAL H.L BEDROOM # 2:

= 3383.7 BTU/hr

Bedroom # 1

WALLS:


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A= 229 ft sq

R=9.75 U = 0.102

Q = 229 * 0.102 * 57.6

Q= 1345.4 Btu/hr

Window:

Q= 460 BTU/hr

Roof:

Q= 1235.3 Btu/hr

TOTAL BEDROOM # 1

Q= 3040.7 BTU/hr

TV ROOM:

Walls:

A=104 ft sq

Q= 104*57.6*0.102

Q= 611.02 BTU/hr

Windows:

Q=460 BTU/hr

Roof:

Q=187.2 * 57.6 * 0.14

Q=1509.5BTU/hr


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TOTAL TV ROOM

Q= 2580 BTU/hr

HALL:

Walls:

A=60 ft sq

R=9.75 U=0.102

Q=350 * 57.6 * 0.102

Q=2056.32 BTU/hr

ROOF:

A= 143 ft sq

Q= 143*57.6 * 0.14

Q= 1153.15 BTU/hr

Total Q= 3209.47 BTU/hr

TOTAL APT # 2

Q=12213.87 BTU/hr


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2.4 TA BLE

2.5 ASSUMP TION:

The heat losses of Apartment 2 is equal to the heat losses of Apartment 3 and 4 because of the same dimensions of the apartments and it is also assume that the heat loss from the floor of Apartment 2 is equal to the heat loss from the floor of Apartment 3 and 4.

Apartment Apartment

# 1

Apartment

# 2

Apartment

#3

Apartment

# 4

Bedroom #1

(BTU/hr)

2627 3040.7 3040.7 3040.7

Bedroom #2

(BTU/hr)

2991.68 3383.7 3383.7 3383.7

TV Room

BTU/hr)

3981 2580 2580 2580

Hall

(BTU/hr)

_

3209.47

3209.47 3209.47

Total 9600 12213.87 12213.87 12213.87


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3 INSULATION

Insulation is the reduction of heat transfer (the transfer of thermal energy between objects

of differing temperature) between objects in thermal

contact or in range of radioactive influence. Reducing

the heat load can save energy and cut your running

costs. It can also reduce the capital cost of a system.


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3.1 TYPES OF INSULA TION:

There are basically four different types of insulation you can use in your home: Blankets of Insulation - Fiberglass and Rockwool Blown In Insulation

- Cellulose and Fiberglass Spray Foam Insulation - Open and Closed Cell Foam Board Insulation - EPS, XPS and ISO

3. 1. 1 INSULA TION USED:

The insulation which is used to insulate the walls of the are cellulose and gypsum while in windows, we

have use double glazed window which helps to lessen the amount of heat loss, on the other hand, we use

polyutheren as insulation which also helps to lower the heat losses.

R(brick)

per inch

R (gypsum)

per 5/8 inch

R(Cellulose) per inch

0.2 0.45 3

9 * 0.2 = 1.8 2.5*3=7.5


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4 BOILER

4.1 WHA T IS BOILER?

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the

boiler for use in various processes or heating applications, including central heating.

4.2 TYPES OF BOLILER

Fire tube boilers Watertube boilers

Electric boilers etc

4.3 SELECTION OF BOILER

We selected fire tube boiler because:

4.3. 1 FIRE TUBE BOILER

where the hot combustion gases pass down a tube and into subsequent bundles of tubes immersed below water level. The heat from these gases is then transferred to heat the water. Most steam and hot water boilers in the UK are derivatives of the shell type, which are also referred to as ‘fire tube’.

4.3.2 OUR BOILER SPECIFICA TION

Specification Vertical Fire Tube Boiler

Efficiency Medium

Floor Space Required Very Low

Maintenance Low

Initial Cost Low

Pressure Range 15 psi

Typical Applications Heating System

Temperature Up to 240 F or 100 C

power 1.2 ton for APT #1 & 1.5 ton for APT #2, 3, 4


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4.3.3 TYPES OF FUEL USED IN BOILERS

There are a wide range of fuels used. Boilers commonly burn standard hydrocarbon fuels, such as natural gas, oil and coal, but some burn tallow or waste materials. Some boilers, known as dual-fuel boilers, can burn gas or oil. This is useful in the rare cases where an interruptible gas supply contract is held. Coal burners can be a variety of designs mainly centring on how the coal is fed to the boiler and burnt. Currently, gas boilers are the most popular type of steamraising or hot-water-producing equipment.

So we are using natural gas

4.3.4 BENEFITS ARE:

Natural gas is convenient. The energy source is piped directly to the customer's facility through the safe, efficient pipeline system. There's no need to store oil on site in tanks, or schedule oil deliveries .

There is an abundant supply of domestic natural gas. Over half of the oil used in this country is

imported. The price and supply of oil is susceptible to international events.

Natural gas is reliable. The pipeline system can't be easily damaged by weather or affected by weather conditions. In contrast, oil must be trucked to the customer's location, and truck deliveries are

susceptible to weather conditions.

Natural gas is the cleanest burning fossil fuel. Because the combustion process for natural gas is almost perfect, very few byproducts are emitted into the atmosphere as pollutants.

4.3.5 COMBUSTION ENERGY

Flame thermal power (thermal load) Mixture composition, gas velocity, heat of combustion of

a fuel

Heat of combustion higher heating value (HHV) (or higher calorific value lower heating value

(LHV) (or lower calorific value)

Fuel HHV MJ/kg LHV MJ/kg

Methane 55.5 50

Fuel + oxidizer products + energy

Combustion is an exothermic reaction between fuel and oxidizer.


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4.4 BOILER LOSSES AND MEASURES OF EFFICIENCY

The operational efficiency of a boiler is measured by the percentage of the fuel input energy that is eventually delivered as useful heat output. Not all of the heat released when the fuel is combusted can be used and some potential heat is never released due to incomplete combustion. Major sources of heat loss from steam boilers are through the flue gas, blow down and radiation to the boiler’s surroundings. See Figure for a diagram of major losses; note that losses in the flue gas are the most significant. Many

measures of performance can be used to define efficiency. Two common ones are combustion efficiency and boiler efficiency, the calculations of which are shown in the example. The box, right, shows how

efficiencies can be quoted. Bear in mind that figures may be expressed as either gross efficiency or net efficiency, depending on whether the gross or the net calorific value of the fuel is used when calculating the energy content of the fuel. Gross calorific value includes the energy (heat) that is held in the water vapour formed during combustion of the fuel. This energy is not included in the net calorific value of a fuel.


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4.4. 1 CALCULA TIONS OF EFFICIENCY –A T A GLANCE

Calculations of efficiency – at a glance Combustion efficiency is defined as the percentage of energy in the fuel that is released after combustion within the boiler. Some of the energy contained in the fuel is

lost due to incomplete combustion. Combustion efficiency (%) = (Actual energy released during combustion x 100)/Total energy content of the fuel.

4.5 BOILER ACCESSORIES

LOW WATER CUT OFF SENSES water level in a steam boiler it will stop burner when water level falls

below a safe level.

A WATER COLUMN with a gauge glass when mounted on the side of the steam boiler allows the

operator to see water level.

A PRESSURE GAUGE AND THERMOMETER mounted or near the boiler outlet to check the

performance.

VENT is use for the exhaust of fuel gases

4.5. 1 SAFETY RELIEF VALVE :

A Safety Relief Valve opens if boiler pressure is

excessive. An automatic system that relieves by

static pressure on both gas and liquid

4.5.2 THERMOSTA T:

A Thermostat is a component of a control

system which senses the temperature of a system

so that the system's temperature is maintained

near a desired set point

A room thermostat constantly measures the air temperature of a space and can be set to

whatever temperature you like. This prevents your home getting warmer than it needs to be.


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When the temperature falls below the setting, it switches on the central heating. Once the room

reaches the set temperature, the thermostat switches the heating off.

4.6 CALCULA TION

4.6. 1 ASSUMTION

We assuming that the steam dryness factor x = 0.10

at temperature 115℃ and at 1.71 bar

So specific volume v=0.104

The volume of the combustion chamber V=3ft³ or 0.044m³

And the volume of pipes an radiators is 6.9 ft³

When Pipes diameter =2.5 inch

So total volume of the system = 0.27m³

Mass of water to be added in system is 2.5 kg


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5 T-S DIAGRAM

5. 1. 1 IN THIS DIA GRAM:

Process 1 to 2: water boil and convert in to steam (constant pressure ).

Process 2 to 3: steam works and passes through pipes

Process 3 to 4 : steam transfer its heat and get condens. (constant pressure ).

Process 4 to 1: work done on the system (pump) or gravitational work


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6 PLUMBING

6.1 BASIC STEAM HEA TING SYSTEMS

6. 1. 1 ONE-P IPE

In a one-pipe, gravity-flow system, each heating unit has a single pipe connection through which it receives steam and releases condensate at the same time. All heating units and the end of the supply main are sufficiently above the boiler water line so that condensate flows back to the boiler by gravity.

6. 1.2 TWO-P IPE

In a two-pipe system, steam supply to the heating units and condensate return from heating units are through separate pipes. Air accumulation in piping and heating units discharges from the system through the open vent on the condensate pump receiver. Piping and heating units must be installed with proper pitch to provide gravity flow of all condensate to the pump receiver.

6.2 SELECTION OF P IPE

We are using one pipe gravity flow system return. And copper tubing

Water circulation in a gravity system is achieved by the change in the density of the water as it is heated by the boiler, which is normally situated at the lowest part of system. A column of hot water weighs less than a column of cold water of the same volume and height, and the heated water will therefore rise from the boiler and the colder water will fall back via the pipe work system to the boiler. The addition to the pipe work of radiators and a heating coil within a storage cylinder utilizes the circulating steam to provide heating and domestic steam

Copper tubing advantages

Frictional resistance is less than steel resulting in the possibility of smaller pump and less power

consumption.

It is not subject to oxidizing and scaling


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APT # Length Diameter Volume

Ground Floor 95‘ 2.5” 6.83 cubic feet

First Floor 105’ 2.5” 6.9 cubic feet

6.3 STEAM MA INS FOR GRAVITY FLOW

Correct pitch for horizontal supply mains and dry returns must be 1/4" min. in 10' in the direction of steam and condensate flow. Arrows indicate direction of pipe pitch.


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7 RADIATOR

7.1 WHA T IS RADIA TOR?

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and

electronics. The radiator is always a source of heat to its environment, although this may be for either the purpose of heating this environment, or for cooling the fluid or coolant supplied to it, as for engine cooling.

7.2 TYPES OF RADIA TOR:

Following are the different types of radiators used in central heating systems.

* Hot Water Radiator

* Hot water Base Board Radiator

* Steam Radiator

* Fan Assisted Radiator

* Under Floor Radiator

* Electric Baseboard Radiator

* Portable Radiator

7.2 . 1 HOT WA TER RADIA TOR:

A hot-water radiator consists of a sealed hollow metal container filled with hot water by gravity feed, a

pressure pump, or convection. As it gives out heat, the hot water cools and sinks to the bottom of the radiator and is forced out of a pipe at the other end.

7.2 .2 HOT WA TER BASE BOARD RADIA TOR

The radiators are designed to heat the air in the room using convection to transfer heat from the radiators to

the surrounding air. They do this by drawing cool air in at the bottom, warming the air as it passes over the radiator fins, and discharging the heated air at the top. This sets up convective loops of air movement within a room.


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7.2 .3 STEAM RADIA TOR

Steam has the advantage of flowing through the pipes under its own pressure without the need for pumping

7.3 WORKING

In practice, the term "radiator" refers to any of a number of devices in which a fluid circulates through exposed pipes

(often with fins or other means of increasing surface area), notwithstanding that such devices tend to transfer heat mainly

by convection and might logically be called convectors.

7.4 MATERIAL

cast iron radiator

steel radiator

aluminum radiator copper and aluminum composite radiator

7.5 RADIA TOR SELECTION

We are using STEAM RADIATOR because Steam has the advantage of flowing through the pipes under its

own pressure without the need for pumping.

7.5. 1 MA TERIA L SELECTION

COPPER AND ALUMINUM COMPOSITE RADIATOR

Copper and aluminum composite radiator to copper pipe as the water component, is a Chinese

characteristics of the radiator, the biggest advantage is resistant to corrosion, also have some of the characteristics of light radiator, is very suitable for independent heating system used in.


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7.6 SIZING

7.6. 1 FOR APARTMENT #2 , 3 , 4

Rooms Height(mm) Length(mm) Width(mm) Heat transfer

(btu\hr)

B.room 1 400 1400 70 3340

B.room 2 400 1600 70 3040.7

T.V room 400 1200 70 2580

Hall 400 1600 70 3209.47

7.6.2 FOR APARTMENT # 1

Rooms Height(mm) Length(mm) Width(mm) Heat transfer

(btu\hr)

B.room 1 400 1200 70 3000

B.room 2 400 1400 70 2627

T.V room 400 1800 70 3981


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8 BIOGRAPHY AND REFERENCE:

http://www.techtransfer.com/resources/wiki/entry/734/#Boilers

http://www.csgnetwork.com/areainftandincalc.html

http://www.waset.org/journals/ijeas/v5/v5-3-29.pdf

http://inspectapedia.com/heat/Steam_Radiator_Piping.php

http://www.jhychina.com/enshownews.asp?id=235

http://www.engineeringtoolbox.com/steam-heating-systems-d_474.html#

http://www.oldhouseweb.com/how-to-advice/hvac-steam-heating-systems.shtml

http://www.youtube.com/watch?v=-17NX9LUk80

Book:

BASIC STEAM HEATING SYSTEMS n One-Pipe n Two-Pipe by Hoffman IIT industries

Design of central heating boiler by technische University Eindhove

Steam and high temperature hot water boilers introducing energy saving opportunities for

business

GETTING THE MOST OUT OF HYDRONIC HEATING SYSTEMS

http://www.waset.org/journals/ijeas/v5/v5-3-29.pdf

http://inspectapedia.com/heat/Steam_Radiator_Piping.php

http://www.jhychina.com/enshownews.asp?id=235

http://www.engineeringtoolbox.com/steam-heating-systems-d_474.html

http://www.oldhouseweb.com/how-to-advice/hvac-steam-heating-systems.shtml

http://www.youtube.com/watch?v=-17NX9LUk80

Education

Central steam heating system report