Directional Controls
Water temperatures leaving the water-heating loop are generally what temp?
No greater than 145°F.
A TXV adjusts the amount of liquid refrigerant traveling through it to maintain a consistent ______.
superheat
New systems come from the factory with the service valves in the closed position with the refrigerant locked in the
outdoor unit
Which terminal controls the reversing valve on most heat pumps?
: O/B terminal
Why do air-source heat pumps usually require auxiliary heat?
Because the heating capacity of the unit drops as house heating requirements increase.
What component is responsible for reversing the flow of refrigerant in a heat pump?
The reversing valve
Capillary tubing is commonly used as a metering device in split ac systems. (True or False)
False.
Window ac units
On a new system that has a service ball valve, the access port is used for pressure testing and vacuuming before turning the ball valve _____ and releasing the refrigerant into the rest of the system.
90°
The outdoor coil is the condenser in:
The cooling cycle.
What is auxiliary heat?
Another heat source added to make up the difference between the heat pump capacity and the house load
The internal piston in the reversing valve is moved from one side to the other by:
Pressure difference.
What prevents the refrigerant from flowing through the outdoor metering device during the cooling cycle?
The outdoor check valve
What is the main difference between a heat pump and a fossil fuel furnace?
Heat pumps move heat instead of creating it.
The indoor coil is the condenser in:
The heating cycle.
What is the most common form of auxiliary heat used in heat pumps?
Electric resistance strip heat
What prevents the refrigerant from flowing through the indoor metering device during the heating cycle?
The indoor check valve
When is the indoor metering device bypassed?
The heating cycle
How can an air-source heat pump heat when the outdoor temperature is cold?
All molecules contain some heat until they reach absolute zero (-460°F).
The outdoor coil is the evaporator in:
The heating cycle.
Refrigerant is responsible for shifting the position of the sliding cylinder of the reversing valve? (true or False)
False
Pressure
What is the purpose of the check valves that are installed in parallel with the metering devices on heat pumps?
To direct the flow of refrigerant around the metering device that is not being used
Why does a heat pump need two metering devices?
One metering device is used for the cooling cycle and one for the heating cycle.
When is the Y terminal energized on most heat pump thermostats?
Both first-stage heating and cooling
The indoor coil is the evaporator in:
The cooling cycle.
What makes the main valve in the reversing valve shift from one side to the other?
Pressure difference from one side of the valve to the other