Pump down and crankcase heaters

[jammzzville]

I am just curious as to what other people's thoughts are on using crankcase heaters with a pump down system. There has been some extensive debate on this topic at work.

We have several pump down systems which also utilize crankcase heaters in the compressors. Some mechanics have protested the idea of replacing failed crankcase heaters on the pump down systems, primarily the systems with compressors that require isolation and removal of the oil charge to do so. They justify this by saying that the compressors are indoors at 75F ambient and that because they pump down, they don't require crankcase heat. What are your opinions on this?

[Chris_Worthington]

Relocated to "Tech to Tech Commercial"

[HuNGRYTeCH]

In my opinion, it is always a good idea to have CC heaters. Just because the system pumps down does not mean you won't have refrigerant condensing in the compressor oil and leading to the possibility of slugging your compressor on start up. Just because the compressors are at room tempature doesn't mean this isn't possible either. CC heaters are a cheap way to prevent the possibility of catastrophic failures.

[western]

I agree cc heaters are a good way to keep liquid out of the compressor on startup. If the pump down system is set up right then there shouldn't be liquid in the cc either. I'm trying to think of a situation where if a component in the pumpdown system (solenoid, valves, controls) fail then the cc heater will save the compressor.

[jammzzville]

I agree. It does no bad having the crankcase heaters operating no matter what the situation is. More often than not in these particular systems a fair amount of liquid will return to the crankcase and mix with the oil. This refrigerant is still in the crankcase despite the fact that the system has been pumped down. I've seen the sight glasses chock full of charge and oil after pump down with a nice icy sump. Come in the next morning, oil level is right where it should be and sump is 120F. I think with the way these systems are ran, crankcase heat should be a necessity.

[hill phoinx kind of guy]

you are spot on

[western]

I guess for long shutdowns or a start up on a package unit when the system never got a chance to pump down then by turning on the heater for a day before start up will keep the liquid out of the crankcase.

[MUNC]

Save washed out bearings as oil floats on the liquid refrig. My vote is for cc heat

[acdave17]

I too say stay with the CCH. Curious why they are isolating the compressor, and loosing oil charge. The well type CCH compressors I’ve seen can be tilted after isolated and charge has been recovered so that oil is not lost. There may be other unknown facts of this instillation I do not understand. If the manufacture put them in, they more than likely wanted them working.

[Failure2Comply]

Maintaining a warm refrigerant free oil sump is the key to compressor life. As long as I can maintain between 115F-125F in the sump all is good.

[jammzzville]

I too say stay with the CCH. Curious why they are isolating the compressor, and loosing oil charge. The well type CCH compressors I’ve seen can be tilted after isolated and charge has been recovered so that oil is not lost. There may be other unknown facts of this instillation I do not understand. If the manufacture put them in, they more than likely wanted them working.

We have Carlyle 06Ds and 06Es for most of the systems with dry-well type heaters, so it's not an issue with those comps. However, most of our pumpdown systems are using Copeland 6RA4 compressors which do not have the dry-well type heaters. When these heaters are replaced in these compressors we just prefer to let the oil drain and replace with a fresh oil charge rather than disconnecting piping, navigating small spaces around certain condensing units, tilting the compressors, etc, etc.

[maxster]

then you get the brain surgeons changing oil on a semi with any style inserted dry/wet and don't power the unit down.they do the oil change nice new oil installed and lose a compressor later on with a burnt out heater that had no load on it

[EZE2489]

Crankcase heater is always a good idea no matter what the application. It simply prevents and insures that absolutely no liquid refrigerant is going to migrate back to the crankcase and cause a flooded start which we all know can blow up start capacitors as well as break off reeds from valve plates.