multi-split heat pump standby losses

bpm636 · 07-19-11, 08:52 PM

I have a Mitsubishi heat pump MXZ-2B20NA-1 just installed in my house together with two 12000 BTU interior units. After monitoring outdoor unit with energy monitor in standby mode I was shocked with bizarre number 180 watts! Compressor heater adds on top of that 40 more watts every other 30 minutes. My installer has checked the current and that is in 0.75-0.95 amps range. He called manufacturer and they said that this is expected. Heating "current test" also shows 0.75a above the calibrated curve. Overall losses per year would be in 1500 kWh range (3 times more than my new refrigerator). Any experience with stand by mode measurements on Mr Slim heat pump? This model is used in many zero-energy-home projects in California. I have pellet stove insert in my home but based on heat pump COP it should be quite competitive and outperform efficiency ( but not overall output) of pellet stove down to single digit temperatures. To save energy I have to turn/off disconnect before/after use of HP instead of set back night time thermostat.

07-19-11, 08:52 PM	#1
bpm636 Lurking Renovator Join Date: Jul 2011 Location: New Hampshire Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	multi-split heat pump standby losses I have a Mitsubishi heat pump MXZ-2B20NA-1 just installed in my house together with two 12000 BTU interior units. After monitoring outdoor unit with energy monitor in standby mode I was shocked with bizarre number 180 watts! Compressor heater adds on top of that 40 more watts every other 30 minutes. My installer has checked the current and that is in 0.75-0.95 amps range. He called manufacturer and they said that this is expected. Heating "current test" also shows 0.75a above the calibrated curve. Overall losses per year would be in 1500 kWh range (3 times more than my new refrigerator). Any experience with stand by mode measurements on Mr Slim heat pump? This model is used in many zero-energy-home projects in California. I have pellet stove insert in my home but based on heat pump COP it should be quite competitive and outperform efficiency ( but not overall output) of pellet stove down to single digit temperatures. To save energy I have to turn/off disconnect before/after use of HP instead of set back night time thermostat.