NATE air to air heat pump 4 heat pumps
The primary function of a reversing valve is to... - ANS-Switch between heating and
cooling
A typical 4 way reversing valve has 3 ports on one side of the valve body, and a single
port on the opposite side of the valve body. To what is this single port connected? -
ANS-The discharge line
Of the three ports on one side of the reversing valve's body, to what is the center port
connected? - ANS-The accumulator
If a heat pump system is low on charge, then the reversing valve... - ANS-Is less likely
to slide
If a reversing valve is leaking under the side, then... - ANS-The pressures will equalize
Most defrost requirements occur at what outdoor temperature? - ANS-Between 35 and
45
The ambient temperature sensor for a heat pump's defrost system should be located... -
ANS-In the inlet air stream to the outdoor unit
If a heat pump's defrost system is initiated by temperature difference, then as the
outdoor coil ices up... - ANS-The temperature difference increases to initiation
If a heat pump's defrost system is initiated by pressure difference, then as the outdoor
coil ices up... - ANS-The pressure difference increases to initiation
Once defrost is initiated, what else usually happens? - ANS-All of the above: outdoor
fan is shut off, the reversing valve is switched to the cooling mode, emergency heat
strips are energized
The balance point of a heat pump can best be described as... - ANS-The point at which
the building's heat loss equals the heat pump's ability to provide heat
The outdoor unit must be located so that... - ANS-All of the above: roof run off is
avoided, defrost water can drain away, is elevated above snow drifts.
The primary function of a reversing valve is to... - ANS-Switch between heating and
cooling
A typical 4 way reversing valve has 3 ports on one side of the valve body, and a single
port on the opposite side of the valve body. To what is this single port connected? -
ANS-The discharge line
Of the three ports on one side of the reversing valve's body, to what is the center port
connected? - ANS-The accumulator
If a heat pump system is low on charge, then the reversing valve... - ANS-Is less likely
to slide
If a reversing valve is leaking under the side, then... - ANS-The pressures will equalize
Most defrost requirements occur at what outdoor temperature? - ANS-Between 35 and
45
The ambient temperature sensor for a heat pump's defrost system should be located... -
ANS-In the inlet air stream to the outdoor unit
If a heat pump's defrost system is initiated by temperature difference, then as the
outdoor coil ices up... - ANS-The temperature difference increases to initiation
If a heat pump's defrost system is initiated by pressure difference, then as the outdoor
coil ices up... - ANS-The pressure difference increases to initiation
Once defrost is initiated, what else usually happens? - ANS-All of the above: outdoor
fan is shut off, the reversing valve is switched to the cooling mode, emergency heat
strips are energized
The balance point of a heat pump can best be described as... - ANS-The point at which
the building's heat loss equals the heat pump's ability to provide heat
The outdoor unit must be located so that... - ANS-All of the above: roof run off is
avoided, defrost water can drain away, is elevated above snow drifts.
