checking Oil Level

[pomdekiwi]

Hi chaps this should be a quickey an hopefully somthing you can clear up for me.

Since being in this trade which is a while now so you think that i should know better, I have been told several differant ways to check the level of compressor oil so my question is ...

When is the best time to get the correct level of oil to see if it needs topping up. When its just started, Stopped for awhile, Running for awhile ??

Once you have the correct level how or what is the best top up method. The compressors i generally work on are a scroll type Danfoss Manurope model SM100S4VA (to be precise)

Many thanks in advance guys

Pom

[chemi-cool]

Oil level should only be checked after the compressor is working for a while.

If the oil level is too low, you should find out where it is in the system.

If a condenser is below the compressor, it can hold oil, the part that has oil in it, is not as hot as the rest of the condenser.

the same in evaporators, the part with oil is not as cold as the rest of it.

there are a few ways to return stubborn oil back to the compressor but that for another time.

On danfoss scrolls, fill up while working through the suction valve or through the capped Schroeder on the side.

[pomdekiwi]

Hey thanks for that chemi-cool.
The compressor in question had a pinhole leak on the liquid line out of the condenser, Needless to say there is oil everywhere but before i shut the system down i checked the compressor whilst it was running and couldnt see a level. The only oil i could see was just running down the site glass on the side of the compressor.

Pom

[GXMPLX]

I agree wth chemi-cool but may I add

Topping should be done, if necessary, only once and keep close frequent observation at least until the first defrost.

If you have to do it twice, having thermal load, I'd recover/open and check where the oil is!

If the oil can be seen in the sight glass, topping should be unnessesary.

Also learn how to read the sight glass, some are tricky.

Too much oil=poor performance

[pomdekiwi]

If you have to do it twice, having thermal load, I'd recover/open and check where the oil is!

Sorry gxmplx not too sure what you mean by that.

Pom

[monkey spanners]

I think he is saying that if you keep having to top the oil level up and it isn't leaking out and the system is not working with a low load, and hence not enough gas speed to bring the oil back to the compressor, that you need to find out where the oil is going rather than keep topping it up.
e.g. we once had a tap in an oil return line that did not have a hole drilled in it through the 1/4" flared bit.

Jon

[GXMPLX]

I think he is saying that if you keep having to top the oil level up and it isn't leaking out and the system is not working with a low load, and hence not enough gas speed to bring the oil back to the compressor, that you need to find out where the oil is going rather than keep topping it up.
e.g. we once had a tap in an oil return line that did not have a hole drilled in it through the 1/4" flared bit.

Jon

Exactly TKS, at partial load a system may trap oil but never at full load.

If it does, there is a design problem.

[GXMPLX]

I should have added that topping is not the solution for solving a partial load oil logging.

In this case if you solved the leak I would wait at least after a defrost or if there's no defrost shut the system down and force it to come back at full load and observe oil level for a while.

If oil keeps low refill once.

There's no reason to fear a sight glass with low oil level in scrolls as long as you can see a level during low load operation.

Always remember there is a time lag for oil to return to the compressor.

[pomdekiwi]

Hey thanks for the advice Guys its very helpfull.

I recon that the oil must generally be low as it had lost so much through the leak that ive just repaired so i am assuming that at least that much should go back in which would probably amount to just under a quarter of a pint in my reconning (going by the amount splashed all over the bottom of the Airedale unit).. althouth its always nice to get the well skilled views from yourselves.

many thanks

Pom

[pomdekiwi]

Ermm ..unless its best not to for some reason of course ??

Pom