The Heat Pump
When trying to trouble shoot a Heat Pump you must first understand how they work. A heat pump can pump refrigerant in two different directions. When being used during the summer the unit absorbs heat by sending vaporized refrigerant to the evaporator and discharges the heat via the condenser outdoors, thus is why the air is hot when you are outside with your hand on top of it. When used during the winter months the unit then uses a four way valve to reverse the cycle, bringing that outside unit inside so to speak. The evaporator coil then becomes the condenser and the condenser the evaporator coil.
The second law of thermodynamics of heat states that heat will always travel from a higher temperature to a lower temperature, which allows the heat pump to operate in the winter. Normally heat pumps are found in the southern region where temps do not get below 25 degrees.
A Heat Pump contains all of the major components as an air conditioning system does, except that the refrigerant coils of the a heat pump are not identified as a condenser or evaporator. They are identified as Outdoor and Indoor coils. The most important component to the heat pump and the item that makes it work is a four-way valve, also known as a reversing valve. This valve has four different ports. These ports are The high side port, which allows superheated vapor to be discharged. The low side port, which allows for the low pressure superheat to the suction side of the compressor. Outdoor port that connects the outdoor coil (outside condenser) and the indoor port which connects to the indoor coil. Two of these ports perform the same function regardless of the operation winter or summer.
Winter Operation allows the high temp vapor to be discharged to the outdoor coil and provides a passage for the low temp superheated vapor back to the compressor.
Summer Operation allows the high temp vapor to be discharged to the outdoor coil and returned back.
Remember this is all done via the four way valve via a pilot-operated reversing valve solenoid and thus is commonly known as the four way pilot-operated reversing valve. Once the thermostat set to a mode of operation, the reversing valve is used to direct the discharge refrigerant from the compressor to either the indoor coil or the outdoor coil thus creating a two way cycle.
Typical heat pump thermostats will consist of seven wires and is covered in another section on the site. However thermostats for heat pumps require special types of control within them. They have the need for changing over the valves and different applications. Anticipators must be located within the thermostats that are set and also adjustable along with changeovers. You will find many different types of thermostats for many different types of systems. There are mechanical and electrical sensors, metallic conducting, some have semiconductor components along with other materials. The thermostat has many different signals including but not limited to mechanical, electrical and pneumatic. The prices of each will depend on the make, model and what bells and whistles are included.
Reviews on heat pumps vary throughout the field. They are very economical when operating and very popular in the southern part of the United States. Western areas are sometimes considered to dry and northern states see too much snow which would cause a blanket around the system thus rendering it useless or very uneconomical. Troubleshooting the heat pump is very similar to any other air conditioner system.
Some of the manufacturers of Heat Pumps are Trane, Carrier, and Ruud that offer specials season discounts depending on your situation.