System performance Exam questions
with complete solutions
1. If the pressure at a given point in an R-410A system is 354 psig and the tubing temperature at that
point is 98°F, what does a T-P chart like the one shown in Table 8-1 tell you? - correct answer -a. The
refrigerant is liquid and subcooled 10°F
2. What air volume flow rate of recirculated indoor air equals one ton of cooling load on the evaporator?
- correct answer -c. 400 cfm
3. What heat quantity equals one ton of total cooling load on the evaporator? - correct answer -C.
12,000 Btuh
4. Which of the following is measured to determine the total resistance to air flow in a ductwork
system? - correct answer -c. input td. Temperature rise across the electric heater
5. External static pressure is the sum of the and the - correct answer -c. absolute supply static pressure,
absolute return static pressure
What is the output of a residential electric furnace when the voltage impressed is equal to 235 V and its
current draw is 40 A? - correct answer -C. 32,080 Btuh
7. Use the collected service data below to calculate the air flow volume for a residential electric furnace:
Voltage = 240 V ac Current draw = 40 A Entering air temperature = 70°F Leaving air temperature = 105°F
- correct answer -b. 867 cfm
8. What is the maximum recommended face velocity for air leaving a supply register? - correct answer -
d. 700 ft/min
9. Temperature readings taken on the refrigerant discharge line 6 in. from the compressor must never
exceed °F. - correct answer -d. 225 F
