Heat Pump & Heating

Two possibilities, and one of them is normal. A heat pump periodically runs a defrost cycle, briefly switching to cooling to melt frost off the outdoor coil — you may see steam and hear a whoosh, and it should end within about 10 minutes. If the air stays cool beyond that, the likely causes are a stuck reversing valve, low refrigerant, or a thermostat calling for the wrong mode.

Auxiliary heat is an electric resistance heating element that supplements the heat pump when outdoor temperatures drop too low for it to keep up. It works, and it is expensive to run. If your thermostat shows auxiliary or emergency heat during mild weather, something is wrong with the heat pump itself and the strip heat is covering for it — that is worth diagnosing before the bill arrives.

Dust that settled on the heat exchanger or strip heat over the long cooling season burns off. It should clear within an hour. A smell that persists, smells electrical or acrid, or is accompanied by a tripping breaker is not dust — shut the system down and call a technician.

Both point to sediment. Hard water deposits settle in the bottom of the tank, insulating the burner or element from the water above and taking up capacity that should hold hot water. The popping is steam escaping through that sediment layer. Annual flushing helps; a heater that has gone years without it may be past saving. This is the clearest example of hard water quietly costing you an appliance.

Ten to fifteen years, with the same coastal-corrosion caveat that applies to air conditioners. Because a heat pump is doing both jobs, it accumulates runtime faster than a separate furnace-and-AC pair would, so expect the shorter end of the range.

Yes — but usually as part of the same visit. The reversing valve, the defrost control and the strip heat only get exercised for a few weeks a year, which is exactly why faults go unnoticed. A pre-season check in the autumn catches them before the first cold front.

For most homes here, yes. Cooling dominates the annual load, and a heat pump gives you efficient cooling plus adequate heating from one system without a gas connection. Homes with existing gas service, or unusual heating demands, are worth evaluating individually rather than by rule of thumb.