Trouble Shooting Commercial Flashcards
Why dose the blower need to be checked at start up
Ensure is turning in proper direction
What’s the main purpose of crankcase heater
Prevent refrigerant migrating and mixing with crankcase oil
Crank case heater is shown how in diagram
Resistor
Crankcase heater keeps oil to what temperature
Higher then the lowest temp in the system
How long before you can do a start up on conditioner with crankcase energized
12 hours
If compressor is rotating in wrong direction it will say
Circuit failure to pressurize
When will the blower turn off when heating cycle stops
90-180 seconds
What’s the fireye , flame sensor control do
Ignites the flame and monitors it
Airflow switch will do what if no airflow is detected
The burners will turn off
Combination gas valve is used , valves opens the burner control is in ……mode
PTFI mode
What’s FSC
Flame safety control
How are airflow switches constructed
Single pole double throw
Modulating gas opens to achieve amount of gas needed true or false
True
How to reset fSC
Push reset
Turn power off
Turn power back on
Unit should be installed no Less then
14” above ground surface
How to adjust airflow switch
Adjust screw until airflow light comes on and turn it back 1/2 a turn
Dual duct systems are how efficient
Energy Inefficient
Dual duct system use how much of the airstream at all time
100 percent
Dual duct VAV systems have what to mix air
Mixing box
Two types of MUA
Direct gas fired
Indirect gas fired
MUA air flow across burner should be
2500-3200 fpm
Modulating bypass damper or profile plate is used for what
Maintain air flow velocities
Electric control panel performs many functions, including
Ignition and flame supervision
Safety interlocks
Temperature control
Most manufacturers provide fans with maximum external pressure at
2 to 3 inches water column
Hoods are sloped out side for what reason
Min effects from wind with bird screen to reduce lager particulate
V Bank filter rack is good for what reason
Larger filter area
Ruduces static pressures
Dampers on MUA are designed to operate how
Fully open or closed
End switch will stop burners from lighting until ?
The dampers are fully opened
HRV’S are designed to operate how
Balanced state
Defrost mode in HRV will come into effect when
Outside temp is -5 c or below
ERV works how
Transfers heat and moisture through the exchanger
Finals steps of install are as per ?
Engineers intent and design
Gas supply pressures are set at ?
5.5 WC to 13 wc
