Efficient Gas-Fired, Forced-Air Heating Systems Flashcards
What is the efficiency of a high efficient furnace?
90-97%
What is the efficiency of a mid efficient furnace?
78-84%
What is the efficiency of a standard furnace?
60%
Standard/mid efficiency gas furnaces are also called ________ furnaces
non-condensing
High-efficiency gas furnaces are also called _____ furnaces
condensing
Where does the combustion air blow force air into?
flue
Is the combustion air prove switch usually open or closed?
open
Are roll out switches usually automatic reset or manual reset?
manual
What are the three types of electronic ignition systems used in furnaces?
Combination spark (DSI), Hot surface (HSI), intermittent pilot
The primary high limit switch is a normally closed device that opens if excessive temperature is sensed in:
the heat exchanger
The intermittent pilot ignition system requires a voltage input of _____ V
120
Are electronic control board features standard for all models of furnaces?
no
List the cycle of operation for a mid-efficiency gas fired forced air furnace
- T stat calls for heat
- Combustion air blower begins
- Air prove switch closes
- Gas valve opens
- Flame rod proves a flame
- Heat builds up in heat exchanger
- Fan blower starts
- Warm air produced
- gas valve de-energized
- fan blower shuts down
What are the four types of humidifiers that can be used on furnaces?
water absorbent, rotating drum, rotating disc, flow through
What is the minimum number of air changes per hour that an average home should have?
.35
