Cold Start

[charlie n]

I'm designing Air cooled chillers for mobile rinks using Bitzer CSH compressors & DX R404a chillers. I've asked the Bitzer rep about using a cold start valve like a Danfoss KDC in the discharge line but he has no idea what I'm talking about. Does anybody have any experience or sugestions?

[chemi-cool]

I don't see any problems, then KDC will open on a set pressure and the compressor will get hot quicker.

I would make sure that the oil in the compressor is kept at about 35°C to 40°c at all times.

[Sandro Baptista]

I see this need as to create a rapid differential pressure to ensure fast start on the lubrication especial when the ambient where the unit is installed is very cold.
I don't know the KDC. I can recommend you to use a PM Danfoss or ICS Danfoss with a CVPP (HP). The valve is mounted on the discharge compression line and the 2nd CVPP pressure take will be at the compressor suction.

How do you decided to mount a cold start valve? Are observing any issues on the compressors?

[charlie n]

Thanks for the suggestions. We haven't built these chillers yet & I don't want to add a KDC or PM valve if I don't have to. I'm wondering if anybody else has installed a Bitzer CSH compressor in a similar situation. The compressor will be out of doors. Ambient temperature can be -5 or -10. We have an oil heater in the compressor and a check valve in the discharge pipe.
I'm building these chillers are in China, not in Canada where my profile says I am.

[Sandro Baptista]

The compressor will be out of doors. Ambient temperature can be -5 or -10. We have an oil heater in the compressor and a check valve in the discharge pipe.

Isolate the oil separator with armaflex or other kind. Also you can apply heating belts around if you want.

[charlie n]

I have a heating band on the external oil separator. I didn't think about insulating it, good idea!

[Sandro Baptista]

The purpose is to keep the oil hot and keep the oil separator pressurized enough. If you have an enough heating band that's okay. Only turned ON when the compressor is OFF, as you certain know.

[TXiceman]

Your Bitzer rep must be a beginner. Contact Sporlan or Parker/R/S for some help on low ambient controls.

ken