Saturday, 12 February 2022

Low Pressure after Compressor shutoff

Have a 3 ton r407c air to water heat pump that occasionally throws a low pressure fault.

Of course it never does this when anyone is monitoring it, temperatures and pressures are perfectly normal during operation when anyone has looked at it.

Over time I noticed that it never occurs when ambient is under 40 degrees / 4 Celsius or over 54 degrees / 12 celcius.

I babysat it for a few hours when the temperature was due to plummet and finally caught it in action.

The low pressure occurs a few seconds after compressor shut off due to setpoint reached / start / end of defrost cycle.

Now since the fault occurs when the compressor isn't running I could set the carel controller to auto reset but I don't want to in case a genuine fault appears in the future.

The unit has copeland zh scroll, sporlan bbine-3-ga txv, plate heat exchanger, well sized receiver. All quality compoenents and works perfectly when the compressor is on.

Any ideas?


source https://hvac-talk.com/vbb/threads/2236421-Low-Pressure-after-Compressor-shutoff?goto=newpost

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