Even in a house with existing ductwork, like mine, heat pumps can be prohibitively expensive in cold climates due to the current need for a backup heating system. I have central air and associated ductwork and could have hooked a heat pump into that fairly easily and cheaply. But there was no way to install a backup heating system feeding into the existing ductwork. The quote to redo all the ductwork, repair all the drywall, paint, remove radiators and refinish floors under them/paint behind them, and install the heat pump was about $60k (<2,000sf house). So that was a no. If you don't care about aesthetics, you could put baseboard electric heaters throughout your house for the backup system, but I was not interested in doing that for very modest energy savings over oil. I also wonder about the service life of heat pumps vs boilers.My late 1940s house in the Northeast originally had a coal-fired boiler (the chute's still there) and was later retrofitted to use an oil-fired boiler. It heats the place well, and isn't too expensive to keep ~2100 sq ft/ ~200m^2 heated through the heating season, but will eventually need replacement.
I'm hoping to hold out until the tech for air-to-water heat pumps improves to the point that directly replacing the oil-fired hot water heater as the source of domestic hot water and hydronic (radiator) heating is feasible in my climate. You take an immediate 30% bite out of your efficiency gains going from hydronic to forced air, and tearing out radiators and putting in ductwork is added annoyance and expense I'd like to avoid.
The main limiting factor seems to be that current-tech heat pump efficiency takes a nosedive when heating to temperatures (> 160F/70C) that work well with radiators sized to heat a house, to the point that it's unviable. In a new build or strip-to-the-studs remodel, this wouldn't be a problem because you could simply upsize the radiators or go with under-floor hydronic heating (and potentially high-mounted cooling radiators too, since heat pumps work efficiently in both directions), but in a house that's lived in it's presently a dealbreaker. Drill-and-fill wall cavity insulation* could also potentially reduce the required load to the point that a lower temperature could work with the existing radiators, but again, disruption of the living space. External continuous insulation can also help tremendously in this regard, but it generally makes sense to do that when the siding needs replacement.
* This is assuming the low-hanging fruit, like attic air sealing of penetrations and top plates, attic insulation, basement insulation, etc. have already been done; obviously I'm handwaving a lot of details away here
Statistics: Posted by ETK517 — Thu Feb 01, 2024 10:43 am — Replies 18 — Views 1360