sammy

Anyone have experience with icm325 head pressure control. I heard it cant be used if system does not have a txv. Why would that be if we are just reducing condenser fan motor speed to maintain head pressure? Any input would be great!

JohnH1

Higher head PSI = higher suction PSI This keep the evap from iceing up. I am not fermiler with the controll but I would assume that is the basics. Are you trying to operate durring cold weather?

sammy

It must operate at any outdoor temperature. I would say coldest being 15f.

beenthere

Because a TXv will close down as the evap gets colder. But a piston/fixed metering device system can and will over feed the evap while the ICM is keeping the pressure higher.

Then even after the ICM stops powering the condenser fan. The evap is flooded and will begin to frost over, and can feed liquid refrigerant back the the compressor.
Once most of the liquid is out of the evap. The condenser will begin to builds head pressure again, and start to over feed the evap again.

A TXV helps to prevent this from happening.

I do have several on piston systems that need to run when its 40° outside, and they work ok. If they run them when it below 40, they begin to frost up.

If your going to use them on piston systems. And these systems are for electronic rooms where humidity removal is not a problem. Increase your evap air flow to 450CFM per ton or more.

Of, just install a TXV.


PS: If your going to run them at 15° OD temp, install crank case heaters, if you want the compressors to last.

__________________
How many times must one fix something before it is fixed?