LESSON 4 ANSWERS TO SELF TEST EXERCISES
1. In a one-pipe system, hot water is pumped through at least one main (depending on the number of circuits) and
passes through each radiator in turn. Since the water is at a lower temperature at the last radiator in a given
circuit, the (c) last radiator in circuit will be larger than the first radiator in order to have the same heat transfer.
(para 4-2,a)
2. In a two-pipe system the water is pumped through at least one main, direct to each radiator. The radiators will
generally be the same size. The (d) cool water leaving radiators returns to the heater through separate return
piping. (para 4-2,b)
3. Figure 4-8 shows that the water leaving the hot-water heating boiler travels in two directions, thus forming two
circuits. Since each circuit requires a hot-water return line, two lines are needed. (para 4-2,c) (fig 4-8)
4. The heating system piping is specified as 1 inch. (para 4-2,c) (fig 4-8)
5. An attempt is made to locate furnaces centrally so that duct lengths will be equalized. (para 4-3,b)
6. Figure 4-1 lists heating piping symbols and shows (a) to be make-up water, (b) medium pressure return, (c)
hot-water heating return, and (d) a medium pressure steam line. (para 4-1,c) (fig 4-1)
7. Figure 4-2 lists various heating symbols. (a) is a thermostatic trap, (b) is a float and thermostatic trap, (c) is an
exhaust or return register, and (d) is a supply register. (para 4-3,a) (fig 4-2)
8. Figure 4-10 illustrates several duct connections. (a) is a horizontal elbow, (b) is a vertical elbow, (c) is a
straight tee, and (d) is a split tee. (para 4-3,b) (fig 4-10)
9. The control subsystem consists of the compressor motor, fan motor, starting and running circuit, relay,
pressure or temperature control switch, and thermostat. (para 4-5)
10. The air path includes the ductwork, grills, dampers, and screens. (para 4-5)
11. The duct connecting the sick call room with the medical office is shown as a 12 x 8. (para 4-5) (fig 4-14)
12. Note 9 specifies that heating coils in AC units are to operate at 30 psi per steam. (para 4-6) (fig 4-14)
13. The legend explains that a mercury type cooling thermostat will be represented by the abbreviation TC. This
abbreviation is found in the operating room, dental officer's office, and sick call room; therefore, three cooling
thermostats are specified. (para 4-6) (fig 4-14)
14. Note C of figure 4-17 shows the capacity for each compressor in a 100-foot building to be 40,000 BTU. (para
4-10) (fig 4-17)
15. For a 52-foot warehouse, one unit cooler is required, whereas two unit coolers will be needed If a 100-foot
warehouse is constructed. (para 4-10) (fig 4-17)
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