Tandem Compressors

[lana]

Dear All,


I have a question about Tandem compressors, both single and double stage one.

(pictures are attached)

Can we shut down one of the compressors while the other is operating? (Both cases)

I have asked this from 5 people but I have no satisfactory answers so far!!!
Also I asked Bitzer but still waiting for their reply.

Appreciate any inputs.

Cheers
LANA

[750 Valve]

What exactly do you mean by "shut down" - Decommission permanently or temporarily?

They are basically 2 separate compressors joined by the motor bell housing, there is no issue in running one and not the other. If oil is of a concern and you could put a balance line between the 2 crankcases just in case but the height of the operating oil level will see the same level in both compressors.

[lana]

Thanks for the reply.

By shut down, I mean switching it off when capacity decreases or whenever is necessary.

I found a technical paper from Copeland today which is about single stage Tandem compressors. In this paper also mentioned that one of the compressors can be switched off while the other is operating.

BUT I could not find anything about double stage tandem compressors?!!

Thanks.

Cheers
LANA

[chemi-cool]

In cooling units for laser cutting machines there tandem units, they are not always run together,
They are oil balanced.

The only problem I see is that if one motor burnt out, the oil in good compressor should be changed, in big units, can be a pain..

[lana]

Thanks for the reply.

Is there any tandem compressor which has one single wiring and one single rotating shaft?
If this kind of compressor exists then both compressors run together (I am not sure if there are any).

Still I am wondering about double stage tandem!!

Cheers
LANA

[JIMPANSY]

York used Copeland tandem compressors on a lot of early YCVA chillers, each comp had a single unloader, control was a simple 4 stage controller, many a time only one comp would run unloaded.

As the suction refrigerant / oil is common being joined by a bell housing not having the 2nd comp running was never a problem, the only issue that ever arouse was where a system was on constant low load and only one comp ever run the swept volume was down and you see the oil level drop off.

If possible run the system on full load if this happens to return any oil back to the compressors.

[GHAZ]

Hi its better to have 1 big 2stage compressor and it will work better then 2 comps on single stage tandem is ok. The comps dont need to be join at suction cover.only common discharge and suction needed. With oil balance line. And comps can turn on and off singley.

[lana]

Thanks all for your inputs.

Cheers
LANA