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Peedee
09-03-2009, 12:08 AM
Hello, what is the function of Crankcase heaters on air conditioning compressors with respect to both Water chillers and split AC's ?:)

Brian_UK
09-03-2009, 12:27 AM
It's function is the same regardless of usage.

It is to keep the oil warm so that refrigerant does not accumulate in the crankcase.

US Iceman
09-03-2009, 01:41 AM
One thing that may be confusing to people is why some compressor units will have crankcase heaters installed on or in the compressor and other compressors may not have any installed. It helps to understand the overall application of the equipment and it's location.

Compressors installed outdoors in cold applications make this a mandatory requirement. During the off-cycle the compressor can cool down and allow the oil to dissolve in the refrigerant. When the compressor starts up on the next run cycle the diluted oil thins out (lower viscosity) and can wreck a compressor.

In general practice it is always a good idea to have a crankcase heater installed on the compressor. Usually when you do not see a heater installed on the compressor it is either due to:



Someone did not understand why they are required, or
Someone tried to save money!

K.R.Iyer
09-03-2009, 10:01 AM
Some good points from US Iceman.

One more category of people I have seen is the ones who do not "connect" a heater which is very much a part of compressor supply!!

multisync
09-03-2009, 10:39 AM
It's function is the same regardless of usage.

It is to keep the oil warm so that refrigerant does not accumulate in the crankcase.


You after a teaching job helping out on all this homework?

Brian_UK
09-03-2009, 07:50 PM
You after a teaching job helping out on all this homework?
I know, just can't help myself some evenings. ;)

NH3LVR
10-03-2009, 01:56 AM
Not really applicable to Chillers and AC I guess, but another reason to install a crankcase heater does come to mind.
I have seen many instances of small medium temp rooms where the compressors would not start in cold weather. This was caused by the outside temperature keeping the pressure too low to engage the low pressure switch.
If you see a light bulb hung next to an outdoor condensing unit, you know why it is there!
Of course the oil dilution referred to by US Iceman is happening at the same time.