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The big issue in New England is that heat pumps (ASHP or GSHP) are only really possible for new builds. Most existing homes will likely be forced hot water and

by lsllc 3y ago

The big issue in New England is that heat pumps (ASHP or GSHP) are only really possible for new builds. Most existing homes will likely be forced hot water and there isn't any heat pump out there that will produce water hot enough (e.g. 185F), so your only option is to retrofit ducting (or go mini-split but then you need one in every room). Even homes with ducted AC, it's likely they are sized for cooling only, not heat (not enough CFMs).

evandev 3y ago
While I agree that a heat pump can't work with hot water baseboard, there is an alternative. The alternative is removing the baseboard and with a calculated heat load, replacing with panel radiators which run with much lower temperatures. The retrofit wouldn't be too difficult (compared to ducting) as it would involve running 1/2 inch PEX to each room.
kenmacd 3y ago
> here isn't any heat pump out there that will produce water hot enough (e.g. 185F) For 185: https://www.arcticheatpumps.com/high-temperature-heat-pump.html https://www.arcticheatpumps.com/high-temperature-heat-pump.h... Or much more common, if you can deal with 176F, the SANCO2 ones will generate that down to -20F. The hydronic temperatures you're talking about are only required if you have to stick with the existing radiators. They make radiators with little fans that work at lower temperatures, or larger panel radiators. There's lots of options for lower temperature forced hot water.
- lsllc 3y ago
  That's interesting, I hadn't yet seen any heat pumps capable of producing water that hot. As far as replacing baseboard goes, if you're going to go to that expense, then probably it's just best to switch to forced air since you also get AC. But you'd be looking at probably close to $40K to entirely replace a forced hot water system with a heat pump and forced air (and/or replacing baseboards) as well as a DHW system of some sort -- so quite cost prohibitive.

by lsllc 3y ago

evandev 3y ago

While I agree that a heat pump can't work with hot water baseboard, there is an alternative. The alternative is removing the baseboard and with a calculated heat load, replacing with panel radiators which run with much lower temperatures. The retrofit wouldn't be too difficult (compared to ducting) as it would involve running 1/2 inch PEX to each room.

kenmacd 3y ago

> here isn't any heat pump out there that will produce water hot enough (e.g. 185F) For 185: https://www.arcticheatpumps.com/high-temperature-heat-pump.html https://www.arcticheatpumps.com/high-temperature-heat-pump.h... Or much more common, if you can deal with 176F, the SANCO2 ones will generate that down to -20F. The hydronic temperatures you're talking about are only required if you have to stick with the existing radiators. They make radiators with little fans that work at lower temperatures, or larger panel radiators. There's lots of options for lower temperature forced hot water.

lsllc 3y ago
That's interesting, I hadn't yet seen any heat pumps capable of producing water that hot. As far as replacing baseboard goes, if you're going to go to that expense, then probably it's just best to switch to forced air since you also get AC. But you'd be looking at probably close to $40K to entirely replace a forced hot water system with a heat pump and forced air (and/or replacing baseboards) as well as a DHW system of some sort -- so quite cost prohibitive.