We have Carrier High Performance heat pump, installed in the past 8 months. This past week, we have had heavy snow (30") and ice (outdoor temperature 20F-25F) in our DC/MD area, but the heat pump heating function has been fine. Each day when I have been sweeping the snow away from the outdoor unit, the fan blades have been turning normally. This morning, however, I noticed the fan blades were not turning and that a large amount of snow and some ice had built up on the blades. (But the heater function had still been working OK during the night.) As soon as I removed the snow, the fan started up, but it was then badly out of balance, causing the whole unit to shake. I turned off the heat pump, removed the grill with the fan-motor unit, and scraped off ice that had built up mostly on two of the blades. After replacing the fan and grill, the fan now turned smoothly, without shaking. We have a wood stove that also provides heat to the main part of the house, and the heat pump unit shuts off when the wood stove is fired up. Maybe the snow is building up especially during these times. Now I am turning on the heat pump for a minute or two, every hour or two, when the wood stove is operating, to prevent snow build up again. What I would like to know, in case this happens again: Is it important to have the fan turning for the heating function of the heat pump to operate efficiently during winter weather like this? If so, is there anything I could spray on the blades to prevent ice and snow build up? Other suggestions?
Gary, Washington Grov, MD
If the weather conditions are bad and snowy, the heat pump has to be kept clear to operate properly. With 30 inches of snow, this may be a difficult task. The heat pump should be shut off and the emergency heat turned on until the weather conditions improve. After the snow stops I would clear off the top of the heat pump and shovel out around the unit. Also, inspect the unit for ice and pour warm water on the ice if you notice any in the fan blade area. Regarding the wood stove, it sounds like the heat from the wood stove is satisfying the thermostat and shutting off the heat pump. Although some people do not like to use the emergency heat due to the cost, keep in mind that the heating elements do come on under colder conditions and every time the heat pump goes into defrost mode anyway. I suggest you contact a professional HVAC contractor, such as the ARS/Rescue Rooter branch in Laurel, MD at (301) 927-7100, if you need further assistance with your heat pump.