Superheat

On a reciprocating compressor with unloaders (such as a Carrier 5H60) using a direct expansion (TXV) would one have to have the compressor completely loaded (all 6 pistons active) to set the superheat or could it be set at any given compressor stage as long as the system load isn't fluctuating. My thoughts are, all stages of loading have to be active... and then as the compressor unloads the TXV will adjust accordingly. Thanks ..

Always a difficult one to get just right.

You will have to adjust it for one stage and then make sure it is acceptable for all the other stages.
Personally I would, as you describe, set it for the 100% load and then check thet it works on all the other load situations. But depending on the matching of the TXV duty VS the system duty you might find that you will have to set it for, say 75%, load and accept what the super heat becomes at 100%.

In an ideal world the capacity of the TXV would cover the whole range of the possible duties of the system but in real life they rarely do.

:cool:

Thanks. I talked to another and that person basically said about the same thing.. so, I will just do it best as I can and check it periodically till satisfied !!