Heat pump defrost control
OwnerReynold Kenneth Lawson, SR.inventor
Life of this patent
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Abstract
An electronic defrost system consisting of a circuit board designed to implement defrost cycle of an air source heat pump outdoor coil during the off-cycle period. off-cycle is when the house thermostat is satisfied, heat pump is timed off for two minutes and then reactivated in regular defrost cycle if defrost sensor is calling for defrost. (Temp/off cycle). When sensor opens, heat pump will shut off for two minutes to allow pressure equalization. The automatic emergency heat is an option that can be selected. The automatic setting will activate the same circuit as the manual switch at the indoor house thermostat. Defrost control board designed to activate all heat strips during defrost cycle if desired.
Claims3
A defrost control apparatus designed to activate defrost cycle during off-cycle period,
- A. The circuit board is designed to defrost the outdoor coil every time the heat pump shuts down if defrost sensor is closed, This is a temp/off cycle mode, The unit will have a frost-free coil on start-up,
- B. Another board design function is if ambient temperature is too cold for house thermostat to satisfy, a selector switch set on 30/60 minutes will force the unit off on time/temp, and perform the same off-cycle defrost as the temp,/off cycle.
An automatic emergency heat circuit will energize all heat strip relays or sequencers if balance-point stays approximately two degrees below indoor thermostat set-point for thirty minutes. Compressor and outdoor fan motor will be off during this time.
As in prior art defrost cycles, the auxiliary heat (normally one heat strip) energizes. The present invention will give owner an option to energize all heat strips for entire defrost cycle,
- A. This will eliminate cold-blow for an acceptable temperature.
Dependencies are inferred from the claim text.