CHAPTER 7
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 7.2 describes criteria for selection of fuel
source. This is potentially the most important early decision in systems planning.
• Various types of heating equipment along with guidelines for when each might be
appropriate.
• Selecting the heat transfer medium.
• Details of sub-systems and operations. This material is a good primer for facility
managers overseeing operations including large heating equipment. The material is
also beneficial for professionals who work with the HVAC engineers to be
knowledgeable for communicating to coordinate the overall design.
• High level early planning considerations for selecting the location of central heating
equipment. This material comprises a checklist for programming building
mechanical space locations in conjunction with other architectural necessities.
• District heating, which is an alternative to boilers located in the building. This option
is available in many metropolitan areas and has significant economic implications,
which are described in this section.
• Alternative heat sources including cogeneration, fuel cells, and solar are discussed
with realistic appraisals of their economic viability.
CHAPTER 7
HEATING PRODUCTION EQUIPMENT AND SYSTEMS
QUESTIONS AND ANSWERS
7.1 If gas is available at $1.00 per therm and #2 oil is available at $2.00 per gallon, which
will be the more economical fuel source on the basis of cost per Btu ? (Assume 80%
utilization efficiency.)
7.2 If gas is available at $1.00 per therm and the efficiency of utilization is 95%, what is the
net cost of heating energy in dollars per million Btu? How could 95% efficiency be
achieved?
7.3 If electric is available at $0.06 per kWh, what is the cost of electric for heating in
dollars per million Btu?
7.4 For a 20,000 ft2 building using 25,000 Btu/ft2/year, how much energy cost would be
saved annually by using a 95% efficient heating production system rather than a 85%
efficient system? Assume $1.00 per therm.
The building will use 20,000 ft2 x 25,000 Btu/ft2/year = 500 mmBtu/year. Gas at 95%
7.5 For the building in the preceding question, how much energy cost would be saved or lost
annually by using a 95% efficient heating production system rather than an electric
heating system? Assume $0.06 per kWh.
7.6 What is the chief limitation preventing air furnaces from being used in heating
systems for large buildings?
7.7 When might steam boilers be preferable to hot water boilers for a large building
system?
7.8 What characteristics of a Scotch marine boiler should be considered in selection for
a building application?
7.9 What characteristics of a water tube boiler should be considered in selection for a
building application?
7.10 What characteristics of a cast iron sectional boiler should be considered in selection
for a building application?
7.11 Describe advantages and disadvantages of power burners in comparison with
atmospheric burners.
7.12 What special provisions must be made for a heavy oil storage and distribution
system?
7.13 What special provisions must be made for underground oil tanks to comply with
environmental regulations?
7.14 When will a pressurized loop oil supply system be preferable to a simple suction
system?
7.15 What is the purpose of boiler blowdown?
7.16 Name the chief safety features applicable for commercial and industrial boilers.
7.17 Which of the fire tube and water tube boilers are more responsive to l qoad changes
and why?
7.18 Why is nitrogen pressurization required for MTW and HTW systems? Why not
air?
7.19 A heating plant requires 4000 MBH of heating capacity. Select the approximate
pipe size for the main if the plant is:
(a) 200F. hot water system
(b) 5 psig low steam system
(c) 150 psig high pressure steam system
7.20 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?
7.21 What are the major chemical components of natural gas?
7.22 What is the natural draft (in. w.c.) created by a chimney 120 feet tall with a mean
chimney temperature of 400F. and the ambient temperature of 65F.? (Note:
Equation (5-4) is given in degree Rankine which is (F. + 460).
7.23 Name the factors for selecting heating plant locations.
Convenience and economics of running a chimney to the roof, relative ease of integrating
7.24 What are the four basic principles for water treatment?
7.25 Hydronic heating systems are normally closed loop. What does this imply regarding
changes in temperature of the water?
7.25 How are multiple boilers controlled to assure that they fire at approximately equal
output?
7.26 Why does water treatment by replacement of calcium salts with sodium salts
prevent scaling in boilers?
7.27 What are general criteria for sizing boilers for a two-boiler plant? For a three
boiler plant?
7.28What are the functions of a complete feedwater system as illustrated in Figure 7-8?
7.29 What factors are so important that heating plants require special care in design?
7.30 Fuelcells have several benefits which may someday result in their general use in
buildings. What are the benefits?
7.31 Your client is planning a high-rise headquarters office building in a central business
district where district steam is available. How would you counsel himon the pro’s
and con’s of using district steam rather than constructing a boiler plant on site?
7.32 Your client from Question 5.33 is also considering cogeneration as an option for his
office building. What is the most serious factor that will prevent the economics
from being favorable for this application?
7.33 What applications are most efficient for solar collector systems? Why?
7.34 Based on your answer to Question 5.35, why is passive solar heating the most
efficient application for solar energy?