Roy …Pay no attention to Kevin.
However , It would be informative if we knew why this was a practice back then…Huh ?
Roy L.
Sorry guys there were crank case heaters on some compressors for over 50 years that I am aware of personally
Really !!! I have never seen a heater with a crank case let alone a crank case heater. What school did you learn this in. Oh ya never attended a school ya just dreamed that up like so many of your thoughts
Installationedit]
Some air conditioning equipment manufacturers install crankcase heaters either in the compressor (insertion type), or mount them externally around the base of the compressor (bellyband type). The two wires of the heater are wired directly to the input side of the contact from the main power supply, and power is always supplied to the heater. Caution should be used since the heater can become very hot and cause second degree burns as well as cause electrical danger due to live circuits.citation needed]
Start-upedit]
Most manufacturers of air conditioning require that the heater be energized for 24 hours before system start-up. The compressor must have crankcase heat before start-up or damage occurs to the compressor.[2]](Crankcase heater - Wikipedia) The crankcase pressure of the compressor always drops when the compressor starts to turn.[3]](Crankcase heater - Wikipedia)
Operationedit]
While the system is running, there is enough heat being generated by the compressor running to prevent refrigerant migration from occurring. Refrigerant vapor always migrates to the coldest part of the system (the compressor). The refrigerant migrates to the compressor crankcase where it is attracted to the compressor oil. This refrigerant vapor condenses and returns to a liquid in the off cycle. On the next start of the compressor, the oil is in a watery state and washes the bearings out, which leads to locked-up, frozen or totally burnt-out compressors.[4]](Crankcase heater - Wikipedia) The temperature is sensed at the compressor, indoor coil, and outdoors. The sensed temperatures are compared and if the compressor temperature is not a specified amount higher than the lower of the other two sensed temperatures, then the crankcase heater is energized. When the compressor temperature rises to or is a specified amount above the lower of the other two temperatures, the crankcase heater is de-energized.[5]](Crankcase heater - Wikipedia)
Crankcase heat is common in air conditioning (cooling) systems where R-22 has been used for many years. The home owner often shuts off the disconnect to the outdoor condensing unit for the winter, leaving the compressor without crankcase heat. If the homeowner then starts the unit without some time for the heat to boil the refrigerant out the oil, damage likely occurs to the compressor. On start-up, the crankcase pressure reduces as soon as the compressor starts to turn. The refrigerant boils and turn the oil to foam. The oil and refrigerant (some of the refrigerant may be in liquid state) is pumped out of the compressor. Valve and bearing damage may occur and the compressor may be operated with a limited oil charge until it returns to the crankcase from the evaporator.citation needed]
Refrigeration compressors typically operate all seasons and do not have this seasonal shutdown, but if they are shut down for a period of time, the preceding situation occurs, so it is likely that crankcase heat will become popular.[6]](Crankcase heater - Wikipedia)
Roy I was mocking Kevin the way his post was stated implied (heater as being the furnace) with a crank case heater;-)
This OP was about heat pumps not standard A/C units. Most stripped down builder model A/C units do not even have crank case heaters. Most MFG are now using scroll type compressors which have no valves to damage. Not like the old recips
Charles
So I can run a heat or cool test on a HP without worrying about damaging the unit. Correct ?
Could I run a straight cool during cold days ?
Thanks
Roy L.
I do bump the compressor and out door fan over in cold weather but that is just me. I don’t advise HI’s to do that. I have a little different way to do it that I don’t advertise
It was a joke!!! LOL
I twisted it on purpose.
Sure it was; after the fact
Keep thinking Charley! Maybe someday you will figure out when I put the icons on, there is a reason for it.LOL