Copeland Scrolls, in a Pack

[mad fridgie]

Have various applications at -35SST and 40SCT R404a (short piperuns)
looking at using a single model Copeland (Multiples for varing load)
I know this method is very common in European supermarkets.
What is the practical limit on the number of comps paired up?
Is there any thing to be wary of?
cheers
Mad

[Goober]

Not sure what your asking bro...but I've worked here in NZ on multiple scroll racks (packs if your northern hemisphere) same thing applies to multiple scrolls as does to recips....oil return, discharge NRV's, suction/discharge header arrangement....basically all the same...

[mad fridgie]

Not sure what your asking bro...but I've worked here in NZ on multiple scroll racks (packs if your northern hemisphere) same thing applies to multiple scrolls as does to recips....oil return, discharge NRV's, suction/discharge header arrangement....basically all the same...
Thanks Goober, (packs, racks the same) not to worried about basic design as you have stated, but more the bits us design engineers miss, and service engineers pick up. (I have been of the service tools to long)Or should i say what can i do right to make your jobs easier. As an ex service engineer, I saw many good design spoilt by the lack of service detail.

[NoNickName]

The main design issues with packs are:

1) refrigerant flow varies a lot with the number of active compressors. Oil circulation may be negatively affected. High speeds at max load, may cause excessive pressure drops, while low speeds may cause oil not to return at min load.
2) when one compressor burns and cause the oil to become acidic, the other compressors are affected to.

[jwhytock]

a digital copeland scrolls should help maintain regulation pain in the butt mind you to setup lmao

[supermarketguy]

Hi Goober,

In this country, retailers generally have between 6 & 10 scrolls per pack.

The thing with scroll packs is to keep it simple, both mechanically and electrically and have it designed in such a way that all components are accessabile to the engineer and this allows the down time of the pack to be kept to a minimum, whether it be for maintance or repair.

as with the digital / variable scrolls, i have only seen them used on Condensing units and not on a pack set up yet and as mr wytock says, they can be a pain to set up the emerson controller, but all pack controllers are a pain. :o

Bring bach the RT Pressure switch, i say :D

[Silhouette]

How about digi scroll on a Danfoss pack controller, the new larger scroll has the solenoid valve internally on the comp. It has two electrical boxes and sounds like it is start-stopping all the time! The oil level is up and down like a yo-yo.