Greenheck Fan 473501 Heat Pump Overview, Energy Wheel Troubleshooting, Symptom, Possible Cause

Energy Wheel Troubleshooting

Symptom	Possible Cause	Corrective Action
	Air seals are too tight.	See air seals under Start-Up, Energy Wheel
		section.
Energy wheel
	Broken belt.	Replace.
does NOT turn
	No power to wheel motor.	Make sure wheel drive is plugged in. Verify
		power is available.
Energy wheel	Wheel motor overloads are tripping due to	Recheck air seals, make sure they are not too
		tight. See Adjust the Air Seals under Start-Up,
runs intermittently	rubbing between wheel and air seals.	Energy Wheel section.

Heat Pump Overview

Every unit has a complete, sealed refrigeration system that is ready for connection to a water source.

The heat pump has all the typical DX components and also has refrigerant reversing valve(s) to enable the system to work in both heating and cooling modes.

Factory-Installed Heat Pump System Components:

Thermostatic Expansion Valve (TXV)

Each compressor is equipped with a thermal expansion valve. The valve controls the flow of liquid refrigerant entering the evaporator coil by maintaining a constant, factory set superheat of 10ºF.

Refrigerant Distributor

Attached to the TXV is a refrigerant distributor. The refrigerant distributor evenly distributes the refrigerant to each circuit of the airside coil to provide optimum performance.

Airside Coil

Each unit uses a single refrigerant coil known as an airside coil. If two compressors are used in the unit, then the airside coil will be a split configuration so that each compressor has a dedicated portion of the airside coil. Depending on whether the unit is in cooling or heating mode, the airside coil will function as either

a condensing coil or an evaporator coil. See also Subassemblies/Coils.

Coaxial Refrigerant-to-Water Heat Exchanger The unit uses one coaxial heat exchanger per compressor, essentially a tube inside a tube. Water flows through the inner copper tube and compressed refrigerant is forced through the spaces between the inner and outer tubes. Depending on whether the unit is functioning in a cooling or a heating capacity, heat is rejected from one tube to the other.

Liquid Line Filter Drier

The liquid line filter drier prevents moisture and foreign matter from entering the thermal expansion valve. It is located in the compressor compartment.

Hot Gas Bypass Valve

On units equipped with hot bypass, hot gas from the compressor is injected into the liquid line of the airside coil after the TXV. This process starts when suction gas temperatures drop below 28ºF, which is 32º–34ºF coil surface temperature. Hot gas helps the airside coil from freezing up and the compressor from cycling. The valve is factory set, but should be field adjusted to maintain a suction pressure of 90 psi.

Valve Adjustment: To adjust the valve, connect a pressure gauge to the suction line and block the entering air to the coil. The valve should begin to open when the suction pressure drops to approximately 58 PSIG (the valve will feel warm to the touch). Adjustments are made by first removing the cap

on the valve and then turning the adjusting stem counterclockwise to decrease the pressure. Allow several minutes between adjustments for system to stabilize. When adjustment is complete, replace the cap on the valve.

Reversing Valve

Each compressor is equipped with a reversing valve to reverse the direction of refrigerant flow. The valve is electrically actuated.

Access Ports

For easy measurement and charging access, several ports are provided throughout the system. These can be used to measure system pressures and also charge or evacuate the system.

24Model ERCH-HP Energy Recovery Unit