HVAC Exam Review with All Correct & 100% Verified
Answers |Latest Update| Already Graded A+
Heat being transferred through pipe walls in a heat exchanger is an example of which type of heat
transfer? ✔Correct Answer-Conduction
A blower is circulating air around a room; warm air leaving a heating coil circulates to the room, and
cooler air is being drawn back through the heating coil. This is an example of which type of heat
transfer? ✔Correct Answer-Forced convection
Energy is being transferred from an energy source through a space, using electromagnetic waves to
another body which absorbs that energy and converts it to heat. This overall heat transfer
mechanism is an example of which type of heat transfer? ✔Correct Answer-Radiation
A convector is most similar in function to a __________________, but the convector is a more
modern, more efficient version of it. ✔Correct Answer-radiator
Why a convector must be elevated above the floor enough? ✔Correct Answer-•Radiators and
convectors should be placed against outside walls, and under windows to mix with cold air.
•Must be room left under cabinet to allow for air to freely circulate.
Various types of heaters share certain common features. But, a wall mounted unit heater does NOT
have? ✔Correct Answer--Do not have natural convection. They use a fan or blower to force
circulation.
-Lack of mobility is a distinguishing characteristic of wall-mounted unit heaters
Various types of heaters share certain common features. What feature does a unit ventilator have
that the other heaters studied do not have? ✔Correct Answer-•Similar to cabinet type unit heaters
above, but additionally have filter, damper, and outside air inlet.
What is/are the problem(s) with having air inside a steam heating system? Choose all that apply
(Multi-select) ✔Correct Answer-•Air in a steam heating system will:
•Block the free flow of steam.
•Reduce heat transfer from heat exchange equipment
•Promote corrosion, especially in condensate return piping. [4 Fe(s) + 6 H2O(l) + 3 O2(g) → 4
Fe(OH)3(s)] (FYI)
Identify the device shown in the figures ✔Correct Answer-Learn the figures
The improvement of a unit heater over a convector comes from the addition of? ✔Correct Answer-
they use a fan or blower to force circulation.
The main significance of the bronze diaphragm in this valve is? ✔Correct Answer-•The packless
design is a specialized globe type of valve with a bronze diaphragm to seal off valve body from stem.
, •This is to avoid steam leaking at stem.
__________ are often used to aid the return of condensate through the return piping of large
systems ✔Correct Answer-Vacuum pumps
As outlined in this unit, what major requirements must be satisfied by the piping and heating units to
ensure a proper functioning steam heating system? Select all that apply (Multi-select) ✔Correct
Answer-•The piping and heating units of a steam heating system must be arranged so that:
•Steam can flow freely and sufficiently to all units
•Condensate can be removed from units and returned to boiler
•Air can be vented from units and piping
Select all that apply. As outlined in this unit, steam heating systems are classified by (Multi-select)
✔Correct Answer-•Many types of steam heating systems, classed by piping arrangement, or
operating pressure, or condensate return method.
•By piping arrangement: could be one-pipe or two-pipe
•By operating pressure: could be low pressure, or vacuum.
•By condensate return method: system could use gravity return, condensate pump or vacuum pump.
As discussed in this unit, the most important step in the start-up procedure is? ✔Correct Answer-
•Start boiler. As pressure begins to show on gauge:
•Leave a qualified person (certified power engineer) in charge of boiler
•Tour entire system, checking for:
•Leaks
•That all sections of piping and heating units are warming up
•If not receiving steam, they are "air bound."
•Check for closed/broken valve, air vent or steam trap
•Returning to boiler, verify that returns are coming back freely to boiler, condensate receiver, or
vacuum pump.
•Return lines should be warm
•If water being held up in system by trap failures, pump, etc...Level in boiler will drop quickly.
•If so, shut down boiler, find problem, repair.
Answers |Latest Update| Already Graded A+
Heat being transferred through pipe walls in a heat exchanger is an example of which type of heat
transfer? ✔Correct Answer-Conduction
A blower is circulating air around a room; warm air leaving a heating coil circulates to the room, and
cooler air is being drawn back through the heating coil. This is an example of which type of heat
transfer? ✔Correct Answer-Forced convection
Energy is being transferred from an energy source through a space, using electromagnetic waves to
another body which absorbs that energy and converts it to heat. This overall heat transfer
mechanism is an example of which type of heat transfer? ✔Correct Answer-Radiation
A convector is most similar in function to a __________________, but the convector is a more
modern, more efficient version of it. ✔Correct Answer-radiator
Why a convector must be elevated above the floor enough? ✔Correct Answer-•Radiators and
convectors should be placed against outside walls, and under windows to mix with cold air.
•Must be room left under cabinet to allow for air to freely circulate.
Various types of heaters share certain common features. But, a wall mounted unit heater does NOT
have? ✔Correct Answer--Do not have natural convection. They use a fan or blower to force
circulation.
-Lack of mobility is a distinguishing characteristic of wall-mounted unit heaters
Various types of heaters share certain common features. What feature does a unit ventilator have
that the other heaters studied do not have? ✔Correct Answer-•Similar to cabinet type unit heaters
above, but additionally have filter, damper, and outside air inlet.
What is/are the problem(s) with having air inside a steam heating system? Choose all that apply
(Multi-select) ✔Correct Answer-•Air in a steam heating system will:
•Block the free flow of steam.
•Reduce heat transfer from heat exchange equipment
•Promote corrosion, especially in condensate return piping. [4 Fe(s) + 6 H2O(l) + 3 O2(g) → 4
Fe(OH)3(s)] (FYI)
Identify the device shown in the figures ✔Correct Answer-Learn the figures
The improvement of a unit heater over a convector comes from the addition of? ✔Correct Answer-
they use a fan or blower to force circulation.
The main significance of the bronze diaphragm in this valve is? ✔Correct Answer-•The packless
design is a specialized globe type of valve with a bronze diaphragm to seal off valve body from stem.
, •This is to avoid steam leaking at stem.
__________ are often used to aid the return of condensate through the return piping of large
systems ✔Correct Answer-Vacuum pumps
As outlined in this unit, what major requirements must be satisfied by the piping and heating units to
ensure a proper functioning steam heating system? Select all that apply (Multi-select) ✔Correct
Answer-•The piping and heating units of a steam heating system must be arranged so that:
•Steam can flow freely and sufficiently to all units
•Condensate can be removed from units and returned to boiler
•Air can be vented from units and piping
Select all that apply. As outlined in this unit, steam heating systems are classified by (Multi-select)
✔Correct Answer-•Many types of steam heating systems, classed by piping arrangement, or
operating pressure, or condensate return method.
•By piping arrangement: could be one-pipe or two-pipe
•By operating pressure: could be low pressure, or vacuum.
•By condensate return method: system could use gravity return, condensate pump or vacuum pump.
As discussed in this unit, the most important step in the start-up procedure is? ✔Correct Answer-
•Start boiler. As pressure begins to show on gauge:
•Leave a qualified person (certified power engineer) in charge of boiler
•Tour entire system, checking for:
•Leaks
•That all sections of piping and heating units are warming up
•If not receiving steam, they are "air bound."
•Check for closed/broken valve, air vent or steam trap
•Returning to boiler, verify that returns are coming back freely to boiler, condensate receiver, or
vacuum pump.
•Return lines should be warm
•If water being held up in system by trap failures, pump, etc...Level in boiler will drop quickly.
•If so, shut down boiler, find problem, repair.
