# Give up your fossil fuel furnace and get a heat pump instead **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 11, 2022, 6:34pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759 "2022-11-11T18:34:54Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![Stanislaus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stanislaus/32/3391_2.png) [@Stanislaus](https://boards.straightdope.com/u/Stanislaus)\ **Post date:** [November 14, 2022, 1:47pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/81 "2022-11-14T13:47:54Z")
> [@Novelty\_Bobble](#): > > Problem is, the models being suggested require an up-front of £20k+ depending on the changes required (may need insulation work, underfloor heating, bigger radiators water tanks etc.) > > They also cost more to run than gas and output water that isn’t as hot. I’m not sure what the attraction is for retrofitting these. We just had one fitted as part of a hybrid system, and it was considerably cheaper than this, even though the costs included a new gas boiler. Had we gone for a pure heat pump system we would have had to change radiators etc. but the hybrid system (whereby you have a heat pump and a boiler, plus an automated switching system that swaps between the two according to what’s most efficient in the moment) meant we didn’t have to do that. (As a bonus, the Scottish government will not only give you an interest free loan for this kind of work, it will also just hand you the majority of that loan as “cashback” meaning you only pay back about 20% of what you borrow. This was a big incentive.) It’s only been in about a month, but we appear to be using considerably less energy/money to heat the house than in previous years (although it is mild for the time of year too). Anyhow, horses for courses but I wouldn’t dismiss the potential of heat pumps in older houses entirely. Next year we get solar panels and a battery and hook them up the heater to reduce costs further. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 14, 2022, 1:50pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/82 "2022-11-14T13:50:05Z")
> [@Stanislaus](#): > > We just had one fitted as part of a hybrid system, and it was considerably cheaper than this, even though the costs included a new gas boiler. can you describe this system? Does the heat pump heat water for radiators? ---
**Author:** ![Stanislaus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stanislaus/32/3391_2.png) [@Stanislaus](https://boards.straightdope.com/u/Stanislaus)\ **Post date:** [November 14, 2022, 2:06pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/83 "2022-11-14T14:06:19Z")
So waht we used to have is a gas boiler connected to the central heating pipes and radiators. It heated water (not steam) and pumped it through the system. Only one heat input. In the new system, we’ve installed a new device - the switcher - between the boiler and the central heating. Also plugged into the switcher is the new heat pump. So two inputs leading to the switcher, which leads to the central heating system. When we ask for heat in the radiators, the switcher decides how to provide it. In most conditions, it will turn on the heat pump and use this to heat the water in the CH system. If conditions aren’t suitable for that, it will use the boiler. The factors which it considers include obviously the temperature of the system now, the outside temperature in which the heat pump is operating and the efficiency of both devices. But it also considers the relative cost per KWh (which you can manually programme in, as prices change). So you should always be using the most economic input. So far it has almost entirely used the heat pump, as best I can tell, but don’t have enough data to do a proper comparison on costs yet. ---
**Author:** ![doreen](https://avatars.discourse-cdn.com/v4/letter/d/858c86/32.png) [@doreen](https://boards.straightdope.com/u/doreen)\ **Post date:** [November 14, 2022, 2:31pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/84 "2022-11-14T14:31:50Z")
That probably depends on a lot of specifics - I’m saving money ( not thousands but some) but my mini-split system replaced a boiler which was converted to oil from a coal-burning boiler and multiple window/through the wall air conditioners. I might not have saved anything if I had started with a more modern boiler and central air. ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [November 14, 2022, 2:39pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/85 "2022-11-14T14:39:15Z")
> [@jjakucyk](#): > > 15% extra on your heating/cooling seems to me like a small price to pay to make a worthwhile dent in the fight against climate change. Plus the £22k, not such a small price in my opinion. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [November 14, 2022, 3:02pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/86 "2022-11-14T15:02:11Z")
> [@Novelty\_Bobble](#): > > Plus the £22k, not such a small price in my opinion. True, but you have to weigh that against the cost of a replacement conventional system. Those don’t last forever either. Even a plain-Jane kind-of-but-not-super-efficient boiler can easily run $10,000 installed, especially if some of the piping needs to be reworked. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 14, 2022, 3:08pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/87 "2022-11-14T15:08:08Z")
Oooh, that’s exactly what I want. I wonder if it can be found in the US. I have hot water baseboard heat that’s currently heated with gas. At what ~ outdoor temp does it switch over to gas? Do you know the brand name? This is worth reseraching. (My current system is extremely old, and it’s time to replace it.) ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [November 14, 2022, 3:09pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/88 "2022-11-14T15:09:03Z")
> [@jjakucyk](#): > > True, but you have to weigh that against the cost of a replacement conventional system. Those don’t last forever either. Even a plain-Jane kind-of-but-not-super-efficient boiler can easily run $10,000 installed, especially if some of the piping needs to be reworked. The alternative option for our friends is a straight, like-for-like replacement with a new condensing boiler for £3.5k installed and no additional work. In their case certainly it would be a massive outlay for minimal benefit. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 14, 2022, 3:14pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/89 "2022-11-14T15:14:23Z")
> [@Novelty\_Bobble](#): > > In their case certainly it would be a massive outlay for minimal benefit. There’s a reason why new tech in building codes is typically only required for new construction and major upgrades. It often doesn’t really make sense for old buildings. But it sounds like there might be a solution that works for my old house. ---
**Author:** ![Stanislaus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stanislaus/32/3391_2.png) [@Stanislaus](https://boards.straightdope.com/u/Stanislaus)\ **Post date:** [November 14, 2022, 3:15pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/90 "2022-11-14T15:15:51Z")
It’ll switch over at c. 5C. It’s a Bosch but other brands are available. ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [November 14, 2022, 3:16pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/91 "2022-11-14T15:16:45Z")
> [@puzzlegal](#): > > There’s a reason why new tech in building codes is typically only required for new construction and major upgrades. It often doesn’t really make sense for old buildings. But it sounds like there might be a solution that works for my old house. Yes, all new houses should be designed and built in the most efficient way possible with double/triple glazing, suitable insulation, water capture, solar, greywater utilisation and heat pumps etc. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 14, 2022, 3:23pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/92 "2022-11-14T15:23:33Z")
> [@Stanislaus](#): > > It’ll switch over at c. 5C. It’s a Bosch but other brands are available. Hmm, that may be why I haven’t seen it here. That’s our swing season, not our heating season, and barely worthwhile. The heat doesn’t even necessarily come on at 5C, because the house picks up some heat during the day. Although with global warming those days might be more common in the future. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 14, 2022, 4:36pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/93 "2022-11-14T16:36:31Z")
> [@RickJay](#): > > Not for the life of me can I understand how this would save me money. You’re just describing an air conditioner. One obvious issue is once a heat pump is installed you now also have air conditioning where you might not have before (or had before a more limited A/C like a window unit) and that’s going to cost more to run. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [November 14, 2022, 4:42pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/94 "2022-11-14T16:42:43Z")
Hard to cool your house with a natural gas furnace… But, that aside, it depends on the relative cost of gas vs electricity. A gas furnace is never going to be more than 90% or so efficient, but a heat pump can be 300% efficient. So, if electricity is less than 2.5x as expensive then has for the same energy, a heat pump will be cheaper to run. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 14, 2022, 4:57pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/95 "2022-11-14T16:57:51Z")
Calling around… “No, I’m not interested in cooling. I just want a heat pump to heat water…” I already have central AC. That system isn’t suited to heating, but it cools just fine. ---
**Author:** ![Folacin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folacin/32/3195_2.png) [@Folacin](https://boards.straightdope.com/u/Folacin)\ **Post date:** [November 14, 2022, 5:19pm UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/96 "2022-11-14T17:19:21Z")
> [@thorny\_locust](#): > > I am going to talk to the contractors about their experience with heat pumps in this area; and ask whether there are any local people who have one of their systems who I can talk to about it. And I thank everybody for the warnings and the info. A caveat - if the local contractors don’t have much/any experience (or their experience is with older systems), they may bad mouth them inappropriately. [Here is a Vox article on that.](https://www.vox.com/energy-and-environment/2022/10/8/23387530/home-electrification-heat-pumps-gas-furnace-contractors) Of course, you’re going to need local support/installation, so there is going to be a trade-off there (and you don’t want to be someone’s first try either, likely). ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [November 15, 2022, 12:57am UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/97 "2022-11-15T00:57:59Z")
Had the home assessment visit today. This stage basically looks over the house for various factors; we’ll get told eventually what we’d be eligible for in terms of funding. Whether there’d be funding for a heat pump, and if so how much of that would be covered, we don’t know yet; though it seems likely at least I’d get some additional basement and attic insulation. The person who does the assessment says that while there are heat pumps in the general area which have been functioning for a while, they weren’t put in by his company, and he doesn’t know how happy they are with them. His company has just started recently putting them in; we wouldn’t be the first, but they don’t have long-term experience. They’re the ones we have to work with for purposes of this particular grant, though. He said the heat pump and the ductwork would both be outside the building, so the only work that needs to be done in/inside the walls is putting a limited amount of vents in that the outside ductwork would feed into. Sounded like less than one per room, though I’m not clear on that. The outside ducts can be painted as/if desired; I’m not all that concerned about their appearance on the house. The system would indeed provide air conditioning as well as heating. No need to take out the oilburner, but it wouldn’t make any sense to use it as it would be more expensive. Will have to wait and see what we actually get approved for. ETA: Thanks for article, @Folacin. The contractor’s already on-board, finding one wouldn’t be an issue. I note that the article says the technology’s much better than it was some years ago, and that new versions work in subzero F temperatures. Certainly I need one that will work in much colder than 5º C! we don’t get much subzero F here, but it does happen, and single digit F happens moderately often and teens or twenties most of the winter. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [November 15, 2022, 1:15am UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/98 "2022-11-15T01:15:28Z")
That sounds like it might be a ductless, mini-split system, with one or a small number of heat pumps outdoors, pipes carrying refrigerant to the wall units, and a unit in each room or large area, each controlled by a remote. You’d effectively get a separate heating/cooling zone for each wall unit. I have friends who use those, and are happy with them. ---
**Author:** ![Heracles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heracles/32/487_2.png) [@Heracles](https://boards.straightdope.com/u/Heracles)\ **Post date:** [November 15, 2022, 1:20am UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/99 "2022-11-15T01:20:59Z")
> [@RickJay](#): > > Not for the life of me can I understand how this would save me money. You’re just describing an air conditioner. Where I live, an air conditioner is way, way more expensive to run than a natural gas furnace. It’s not even close. How do you calculate that, given that they’re obviously used in different seasons? Do you have central air conditioning now? How much do you pay per kWh? How much does natural gas cost you per winter month? Does your house have air ducts, or is your furnace a water- or steam-based system? ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [November 15, 2022, 1:22am UTC](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759/100 "2022-11-15T01:22:38Z")
You’re in New York State? Have you talked to [Dandelion Energy](https://dandelionenergy.com/)? I saw them on This Old House a couple of years ago. They’re a Google spin-off that installs residential geothermal systems and operates in New York and Connecticut. [Previous page](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759.md?page=4) [Next page](https://boards.straightdope.com/t/give-up-your-fossil-fuel-furnace-and-get-a-heat-pump-instead/974759.md?page=6)