Heating Systems Flashcards
6 cards from real HVAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Heating Systems flashcards as text
What does the term 'balance point' mean in heat pump system design?
Answer: The outdoor temperature at which the heat pump output equals the building's heat loss
The balance point is the outdoor temperature at which the heat pump's heating capacity exactly matches the building's heat loss, requiring no supplemental heat.
Which type of electric heating element is commonly used as auxiliary heat in a heat pump air handler?
Answer: Nichrome resistance heating strip
Nichrome (nickel-chromium alloy) resistance heating strips are the standard electric auxiliary heat elements used in heat pump air handlers.
What is the primary advantage of a two-stage or variable-speed gas furnace?
Answer: Improved comfort and efficiency by operating at lower capacity most of the time
Two-stage and variable-speed furnaces run at lower capacities during mild weather, providing more even temperatures, better humidity control, and higher efficiency.
What is the purpose of the inducer (draft) motor in a modern gas furnace?
Answer: To pull combustion gases through the heat exchanger and vent them safely outdoors
The inducer motor creates a negative pressure draft that pulls combustion air through the burners and pushes flue gases safely out through the venting system.
What does it mean when a gas furnace is described as 'direct vent' or 'sealed combustion'?
Answer: It draws combustion air from outside and vents exhaust gases directly to outside
A direct vent/sealed combustion furnace uses a two-pipe system: one pipe brings outdoor combustion air in and another exhausts flue gases directly outside, without using indoor air.
In a gas furnace sequence of operation, what happens immediately after the thermostat calls for heat?
Answer: The inducer motor starts and a pressure switch proves draft
When a call for heat occurs, the inducer motor starts first to purge combustion gases, and the pressure switch must prove adequate draft before ignition can proceed.