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I am in the market for a heat pump. A bit of back story. When we built our home in 2003, we had plumbing for central heating put in with the idea that we would

I am in the market for a heat pump. A bit of back story. When we built our home in 2003, we had plumbing for central heating put in with the idea that we would get a boiler, a lot of kerosene and get heating. Sadly, but the time the home was finished, kerosene started to reach unreasonable levels which continues to this day. Never had any boiler or even the radiators put in. Over the past year or so , I found how people are using heatpumps to heat the water at 40-55°C, that water can be used to warm the house. Tried to talk to some installers including the one who set up the plumbing, they are not convinced. One said " the life of a heat pump is like 10 years. If you buy one, you will use it only for 10 seasons and the cost of that is quite a lot so the math does not check out. To note, we don't have at whole house heating right now. Tried to find YouTube but there isn't a lot of material on using heat pumps with central heating.

ricardobayes 4y ago
40 to 55C is good for underfloor heating. Which in most cases unfortunately is way too costly to install, in an existing structure as you'd need to rip out all your floors and the ground beneath it, to allow for 8 cm of tubing in a cement structure.
rjsw 4y ago
There is a big push in Europe to replace gas central heating boilers with heat pumps, from before there were any problems with the supply of gas, I think the information available on them will improve quite quickly. My brother has installed one for his house but I have not done yet.
- BonoboIO 4y ago
  Heatpumps at least in Austria are the preferred heating method for like 10 years if you build new or renovate. They just work and it’s interesting to see that they are the new sh*t in the US.
  - kleiba 4y ago
    That's right. My sister's family built their house 11 years ago in Germany, and they have a heat pump too. I think it's pretty standard for new residential builds.
  - mardifoufs 4y ago
    They aren't at all new in the US though? It just depends on the location, and they are very common in some areas
sokoloff 4y ago
I like HeatGeek and once you start watching them, you’ll get plenty of other recommendations. Here’s a reasonable get started video of his: https://youtu.be/D8pvXDk_KAA https://youtu.be/D8pvXDk_KAA I’d expect to get 15-20 years from a well-installed air-source heat pump. That’s not as long as an old, atmospheric boiler, but isn’t that much shorter than a modern modcon boiler in terms of what I’d expect. Even if you got only 10 seasons, I think it would pencil out in most climates/electric prices, provided it can make all your heating load. (It was too questionable for my house, so I’ve had to pass for now, but will be plumbing the system to allow an easy addition of air-to-water to the primary loop.) Given that you’re 18 years without central heat, I’d expect you could get away with just a heat pump.
Nextgrid 4y ago
> I found how people are using heatpumps to heat the water at 40-55°C, that water can be used to warm the house. This would only work for heating though and would have a significant latency (you have lots of thermal inertia in the system). Why not go with standard reversible A/C units which not only would also provide cooling capability but process the air locally so you don't have to wait for pipes/radiators to warm up before actually getting heat?
- ricardobayes 4y ago
  My research lead me to exactly the same conclusion. Heat pumps cost the earth if you call them heat pumps, but once you call them an inverter split A/C they magically cost an order of magnitude less (even though it's the exact same tech).
  - ZeroGravitas 4y ago
    You do get slightly different tech when aimed at air-to-air and air-to-water needs, and different target temps and there's newer generations of the same tech that rivals ground source heat pumps. So its not just a rip off, though there's probably a fair bit of that too as demand has risen recently.
jaclaz 4y ago
There are units which exchange heat with water, but typically they won't reach more than 40-45 C°, maybe 50, I doubt 55, so radiators heating won't work, you need fan-coils or - better - under floor heating. Additionally (it depends) usually pipes used in traditional radiator heating system are smaller in section (when compared to those used in fan-coil heating/refreshing) so your existing pipes may be too small to allow the system to work efficiently. Personally I am not impressed by them, if not in direct small (split) systems, the exchange to water seems like losing a lot of energy. But the good thing is that they allow, in reverse, to cool the house in the warm months (though not comparable to a traditional A/C system). The 10 years duration sounds like what you can expect (to be compared to a traditional burner that would cost less than half a heat pump and is more in the 20+ years duration). There is also the issue that (at least in my experience) they are "slow" when compared to a gas/kerosene/oil burner, so you need to keep the house somewhat heated at all times as it takes more time to raise temperature[1]. [1] there is a lot of debate around whether it is more efficient (with traditional fuel burners) to switch heating off when you are not in the house (potentially letting the temperature go down to - say - 8-10 C°) and boost to the wanted temperature when you are in or keep at all times the house warm (at - say - 13-15 C°) and only increase the temperature to 18-20 C° when you are in
- 2Gkashmiri 4y ago
  what if we use, as you said, FCUs instead of a traditional radiator? i understand other commenters are talking about individual air conditioning but that increases the electrical load exponentially because you have multiple units running at the same time... think of the poor wires. has anyone been crazy enough to preheat the heatpump from solar ? would that even work?
  - jaclaz 4y ago
    As said, very likely the pipes you have (dimensioned for radiators) are too small for fan-coils. There is not much issue with several units, the problem was with electric motors starting (old motors can have something like 5 times normal current peaks when starting) modern motors all have electronics that smooth them down. You mean: https://en.wikipedia.org/wiki/Solar-assisted_heat_pump https://en.wikipedia.org/wiki/Solar-assisted_heat_pump

ricardobayes 4y ago

40 to 55C is good for underfloor heating. Which in most cases unfortunately is way too costly to install, in an existing structure as you'd need to rip out all your floors and the ground beneath it, to allow for 8 cm of tubing in a cement structure.

rjsw 4y ago

There is a big push in Europe to replace gas central heating boilers with heat pumps, from before there were any problems with the supply of gas, I think the information available on them will improve quite quickly. My brother has installed one for his house but I have not done yet.

BonoboIO 4y ago
Heatpumps at least in Austria are the preferred heating method for like 10 years if you build new or renovate. They just work and it’s interesting to see that they are the new sh*t in the US.
- kleiba 4y ago
  That's right. My sister's family built their house 11 years ago in Germany, and they have a heat pump too. I think it's pretty standard for new residential builds.
- mardifoufs 4y ago
  They aren't at all new in the US though? It just depends on the location, and they are very common in some areas

sokoloff 4y ago

I like HeatGeek and once you start watching them, you’ll get plenty of other recommendations. Here’s a reasonable get started video of his: https://youtu.be/D8pvXDk_KAA https://youtu.be/D8pvXDk_KAA I’d expect to get 15-20 years from a well-installed air-source heat pump. That’s not as long as an old, atmospheric boiler, but isn’t that much shorter than a modern modcon boiler in terms of what I’d expect. Even if you got only 10 seasons, I think it would pencil out in most climates/electric prices, provided it can make all your heating load. (It was too questionable for my house, so I’ve had to pass for now, but will be plumbing the system to allow an easy addition of air-to-water to the primary loop.) Given that you’re 18 years without central heat, I’d expect you could get away with just a heat pump.

Nextgrid 4y ago

> I found how people are using heatpumps to heat the water at 40-55°C, that water can be used to warm the house. This would only work for heating though and would have a significant latency (you have lots of thermal inertia in the system). Why not go with standard reversible A/C units which not only would also provide cooling capability but process the air locally so you don't have to wait for pipes/radiators to warm up before actually getting heat?

ricardobayes 4y ago
My research lead me to exactly the same conclusion. Heat pumps cost the earth if you call them heat pumps, but once you call them an inverter split A/C they magically cost an order of magnitude less (even though it's the exact same tech).
- ZeroGravitas 4y ago
  You do get slightly different tech when aimed at air-to-air and air-to-water needs, and different target temps and there's newer generations of the same tech that rivals ground source heat pumps. So its not just a rip off, though there's probably a fair bit of that too as demand has risen recently.

jaclaz 4y ago

There are units which exchange heat with water, but typically they won't reach more than 40-45 C°, maybe 50, I doubt 55, so radiators heating won't work, you need fan-coils or - better - under floor heating. Additionally (it depends) usually pipes used in traditional radiator heating system are smaller in section (when compared to those used in fan-coil heating/refreshing) so your existing pipes may be too small to allow the system to work efficiently. Personally I am not impressed by them, if not in direct small (split) systems, the exchange to water seems like losing a lot of energy. But the good thing is that they allow, in reverse, to cool the house in the warm months (though not comparable to a traditional A/C system). The 10 years duration sounds like what you can expect (to be compared to a traditional burner that would cost less than half a heat pump and is more in the 20+ years duration). There is also the issue that (at least in my experience) they are "slow" when compared to a gas/kerosene/oil burner, so you need to keep the house somewhat heated at all times as it takes more time to raise temperature[1]. [1] there is a lot of debate around whether it is more efficient (with traditional fuel burners) to switch heating off when you are not in the house (potentially letting the temperature go down to - say - 8-10 C°) and boost to the wanted temperature when you are in or keep at all times the house warm (at - say - 13-15 C°) and only increase the temperature to 18-20 C° when you are in

2Gkashmiri 4y ago
what if we use, as you said, FCUs instead of a traditional radiator? i understand other commenters are talking about individual air conditioning but that increases the electrical load exponentially because you have multiple units running at the same time... think of the poor wires. has anyone been crazy enough to preheat the heatpump from solar ? would that even work?
- jaclaz 4y ago
  As said, very likely the pipes you have (dimensioned for radiators) are too small for fan-coils. There is not much issue with several units, the problem was with electric motors starting (old motors can have something like 5 times normal current peaks when starting) modern motors all have electronics that smooth them down. You mean: https://en.wikipedia.org/wiki/Solar-assisted_heat_pump https://en.wikipedia.org/wiki/Solar-assisted_heat_pump