I recently had installed a Carrier Performance 38MGRQ24C-3 Heat pump with 40MAHBQ18xA3 and 40MAHBQ09xA3 air handlers. We live in a small rural home near the Ontario/New York state border so our climate is pretty cool in the winter.
The Product data for the heat pump indicates that on a day such as today (-13F/-25C) we should be able to count on 17.6 KBTU/hr however we don't appear to see anything close to that.
At this outside temperature the system operates on a cycle which appears thus on our indoor units:
Time 0: Louvres move to preset position, fan speed increases and heat is output.
Time +3 minutes: Louvres close, heat stops and dF appears on display.
Time +6 minutes: Display reverts to Set Temp.
Time + ~30 to 45 minutes: Louvres move to preset position, fan speed increases and heat is output.
3 minutes later, dF appears and cycle repeats.
Heat is therefore being output for about 3 minutes every 30 to 45 minutes. During the time the system is "off" at times there is a barely perceptible air flow with a very minor temp increase through the air handler.
According to the Service Manual for the Heat Pump it would appear that the Defrost condition would not occur anything less than 29 minutes after the Compressor starts but since the outside fan seems to be on all the time I can't tell when the Compressor is on.
I am being told this is normal operation. If this is normal then I have a system that will not heat my home when it is less than about -20C outside.
In your expert opinion is this so-called Cold Weather system performing as expected?
The Product data for the heat pump indicates that on a day such as today (-13F/-25C) we should be able to count on 17.6 KBTU/hr however we don't appear to see anything close to that.
At this outside temperature the system operates on a cycle which appears thus on our indoor units:
Time 0: Louvres move to preset position, fan speed increases and heat is output.
Time +3 minutes: Louvres close, heat stops and dF appears on display.
Time +6 minutes: Display reverts to Set Temp.
Time + ~30 to 45 minutes: Louvres move to preset position, fan speed increases and heat is output.
3 minutes later, dF appears and cycle repeats.
Heat is therefore being output for about 3 minutes every 30 to 45 minutes. During the time the system is "off" at times there is a barely perceptible air flow with a very minor temp increase through the air handler.
According to the Service Manual for the Heat Pump it would appear that the Defrost condition would not occur anything less than 29 minutes after the Compressor starts but since the outside fan seems to be on all the time I can't tell when the Compressor is on.
I am being told this is normal operation. If this is normal then I have a system that will not heat my home when it is less than about -20C outside.
In your expert opinion is this so-called Cold Weather system performing as expected?
source https://hvac-talk.com/vbb/threads/2235577-Carrier-38MGR-mini-split-Ductless-Cold-weather-performance?goto=newpost
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