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CHAPTER 5
HEATING PRODUCTION EQUIPMENT AND SYSTEMS
OVERVIEW
The chapter begins by describing ways to classify heating systems by their fuel sources,
energy transport media, and types of equipment. Section 5.2 describes criteria for
selection of a fuel source. This is potentially the most important early decision in
systems planning.
Sections 5.3 and 5.4 describe and illustrate various types of heating equipment along with
guidelines for when each might be appropriate.
Section 5.5 covers another important early decision—selecting the heat transfer medium.
The remainder of the chapter describes and illustrates details of sub-systems and
CHAPTER 5
HEATING PRODUCTION EQUIPMENT AND SYSTEMS
QUESTIONS AND ANSWERS
5.1 If gas is available at $0.50 per therm and #2 oil is available at $1.00 per
gallon, which will be the more economical fuel source on the basis of cost per
Btu (assume equal efficiencies)?
5.2 If gas is available at $0.50 per therm and the efficiency of utilization is 80%,
what is the net cost of heating energy in dollars per million Btu?
5.3 If electric is available at $0.1 per kWh, what is the cost of electric for heating
in dollars per million Btu?
5.4 Name several factors that should be considered in locating a central boiler
plant for a large building.
Central boiler plants should be located to minimize expense to route chimneys,
5.5 What is the chief limitation preventing air furnaces from being used in
heating systems for large buildings?
5.6 When might steam boilers be preferable to hot water boilers for a large
building system?
5.7 What characteristics of a Scotch marine boiler should be considered in
selection for a building application?
5.8 What characteristics of a water tube boiler should be considered in selection
for a building application?
5.9 What characteristics of a cast iron sectional boiler should be considered in
selection for a building application?
5.10 Describe advantages and disadvantages of power burners in comparison with
atmospheric burners.
5.11 What special provisions must be made for a heavy oil storage and
distribution system?
5.12 What special provisions must be made for underground oil tanks to comply
with environmental regulations?
5.13 When will a pressurized loop oil supply system be preferable to a simple
suction system?
5.14 What is the purpose of boiler blowdown?
5.15 Name the chief safety features applicable for commercial and industrial
boilers.
5.16 What is the nominal A.F.U.E. of impulse type furnaces?
5.17 Which of the fire tube and water tube boilers are more responsive to load
changes and why?
5.18 Why is nitrogen pressurization required for MTW and HTW systems? Why
not air?
5.19 A heating plant requires 4000 MBH of heating capacity. Select the
approximate pipe size for the main if the plant is:
(a) a 200
q
F hot water system
(b) 5 psig low steam system
(c) 150 psig high pressure steam system
(a) 4″
5.20 For the same heating plant using natural gas with a heating content of 1000
Btu/cf. what should be the gas flow rate (cf/hr.)? Assume boiler efficiency of
85%. How much combustion air is required with 25% excess air?
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4,710,000/1000, or 4710 cf/hour. Natural gas requires 9.7 cf of air per cf of gas
for stoichiometric combustion. With 25% excess air, the air rate would be 1.25 ×
9.7, or 12.1 cf air per cf gas. For 4710 cf per hour of gas, the air requirement
would be 12.1 × 4710, or about 57,000 cf/hr. of air.
5.21 What are the major chemical components of natural gas?
5.22 What is the natural draft (in. w.c.) created by a chimney 120 feet tall with a
mean chimney temperature of 400
q
F and the ambient temperature of 65
q
F?
Note: Equation 5-4 is given in degree Rankine, which is (
q
F + 460).
5.23 Name the factors for selecting heating plant locations.
Convenience and economics of running a chimney to the roof, relative ease of
5.24 What are the four basic principles for water treatment?
5.25 Hydronic heating systems are normally closed loop. What does this imply
regarding changes in temperature of the water?
5.26 How are multiple boilers controlled to assure that they fire at approximately
equal output?
5.27 Why does water treatment by replacement of calcium salts with sodium salts
prevent scaling in boilers?
5.28 What are general criteria for sizing boilers for a two-boiler plant? For a
three boiler plant?
5.29 What are the functions of a complete feedwater system as illustrated in
Figure 5-8?
5.30 What factors are so important that heating plants require special care in
design?
5.31 What factors are considered in deciding the height of a flue stack?