Heat Pump liquid back in heating

Hi There

We replaced a bristol compressor on a +- 48000 BTU Hideaway York Heat Pump A/C Unit. Fitted a Bio Flo Filter Drier and used a dial a charge to charge the correct amount of refrigerant into the system. We ran the unit in cooling pressures and temperatures are normal. In heating we noticed liquid back to the compressor pressures are normal. Once every +- 10 days of operation the unit switches of on HP safty set at 2400 kpa. We noticed that every time the unit goes off on a safty the indoor fan speed is set on auto and they are running the unit in heating. We are concerned about the liquid back and why out of the blue will the unit pressures be fine when we have placed the gauges on but +- 10 days latter the unit HP Trips out. Any help would be appreciatted.

Regards

Lyle ( Cape Town )

Quote:

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Originally Posted by lyle

Hi There

Any help would be appreciatted.

Regards

Lyle ( Cape Town )

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When you changed the comp did you alter the pipe work at all? Does the system have a suction accumilator on the system?
If you have altered the suction accumilator then that may account for the liquid.

Cheers taz.

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Most folk have moved on from Dial-a-chargers, because they are inherently inaccurant at low ambient temperatures if the heater is not in operation.
They are designed and calibrated for cooling systems in hot climates.

I used them for years and if you are not on the scale due to the pressure in the flask, the inaccuracy for small charges (say a few poinds weight or a couple of Kilos) is significant. In Cold climates (winter on a roof top in the UK or SA) this is particularly important.

One other thing, it may be an air side problem that is dependent on auto fan speed. Assuming that all the ancilliaries like ductwork is OK, is the ID coil clear?

The filters may be OK, but small quantities of dust can stick to a wet coil in the cooling mode and remain. In time they can build up and impair the heat transfer / air flow on an intermittent basis and can be almost invisible inside the fins.

Also, I don't know about your neck of the woods, but I never discount fungus growth in the same place. Again it is difficult to spot visually.

Hope this helps you to think outside the problem.

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I suspect the problem that took out the old compressor is preparing to take out the new compressor. You might want to check the delta-T's (air on/air off temps) across both coils, in both heating and cooling modes.

BTW, "pressures and temperatures are normal" doesn't tell us anything. If the temperatures and pressures were normal, the system wouldn't have a problem, but they aren't normal and it does have a problem.

We can't see the system from here except by your description, so you need to tell us what the temperatures and pressures are and let us draw our own conclusions.