4 ms·

With a 1:1 ratio it's heat energy out = electricity in, minus a small amount of efficiency loss (any heat produced on an external heater) As to cost wise it de

With a 1:1 ratio it's heat energy out = electricity in, minus a small amount of efficiency loss (any heat produced on an external heater) As to cost wise it depends on the cost per kWh of your electricity vs gas. In the UK gas is far cheaper per kWh. CO2 wise it depends on the CO2 intensity of your electric source vs a local gas burner. However that only applies when it's -20C. When it's a more reasonable like now at 7AM in Chicago when it's 2 degrees C, you're generating something like 2.5kWh of heat for every 1kWh of electricity. That may not be financially beneficial if your gas is 5c/kWh and electricity is 30c/kWh, that depends on your various deals. For me in the UK, my external oil boiler this winter has cost about 10p/kWh. My electricity is 21p/kWh. A heat pump I looked at was a 3.84 ratio, so if that ratio held down as far as typical winter temperatures of 6C (it's currently 11C), that would be 5.5p/kWh, and obviously far less CO2 per unit of heat.

Jochim 4y ago
Last time I checked, replacing an existing gas installation with a heat pump in the UK just wasn't economically sensible. Air source heat pumps were barely breaking even compared to gas so you'd be spending £10k+ to install it without saving any money. Ground source heat pumps offered better efficiency but if I recall correctly purchase + installation was a £35k investment that would take decades to recoup. There's also the consideration of additional costs due to lower running temperature which often necessitate larger radiators. They might make more financial sense if energy costs stay high, since they're easier to supplement with domestic renewables.
- monkeynotes 4y ago
  Is that £10k for a mini split system? I'm not sure how many homes would need to spend that much. The UK is full of small flats and 2 up/down places that could rely on maybe one or two splits, Google shows that a decent setup would be about £2k plus installation (two splits each at £1k inc tax). Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain. > There's also the consideration of additional costs due to lower running temperature which often necessitate larger radiators. I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration. Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home.
  - Jochim 4y ago
    > Is that £10k for a mini split system? It was 2021 when I last last looked into it but I recall that 10k was the list price of the cheapest air source heat pump that wouldn't result in a net increase in energy bills. I don't believe it included installation or any other associated costs. > Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain. It's almost unheard of for UK homes to have any sort of cooling installed. > I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration. UK homes are mainly heated with hot water radiators in each room; typically by an on demand gas combi-boiler that also handles hot water. Heat pump installations in the UK typically heat a hot water tank[0] that provides domestic hot water and heats the radiators. Due to poor insulation the gas central heating systems typically run at around 60-80c. Heat pumps here usually heat the water to around 40c. This will often require replacing existing radiators that were installed expecting ~70c flow temperature with oner that can disperse more heat into the room. It can also involve additional insulation. > Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home. Indeed, heat pumps are a sensible choice for most new build homes in the UK as well. They typically have much better insulation and are therefore less affected by the low flow temperature. The costs involved in retrofitting anything older than 10, maybe 20 years old were. [0] https://solarthermuk.co.uk/wp-content/uploads/2020/12/air_source_heat_pump.jpg https://solarthermuk.co.uk/wp-content/uploads/2020/12/air_so...
    - monkeynotes 4y ago
      If you are looking at air to water heat pumps you will certainly be looking at much more expensive installs. Mini splits are way cheaper and don't require hooking up to the gas hot water system which can simply be retired to backup heat source. And yeah, cooling is not a thing in the UK, my point is folks are definitely going to be looking toward that given the summers people have been having, increase heating costs will make mini splits a double win. No brainer to me and I bet mini splits will be in limited supply this summer in Europe.

Jochim 4y ago

Last time I checked, replacing an existing gas installation with a heat pump in the UK just wasn't economically sensible. Air source heat pumps were barely breaking even compared to gas so you'd be spending £10k+ to install it without saving any money. Ground source heat pumps offered better efficiency but if I recall correctly purchase + installation was a £35k investment that would take decades to recoup. There's also the consideration of additional costs due to lower running temperature which often necessitate larger radiators. They might make more financial sense if energy costs stay high, since they're easier to supplement with domestic renewables.

monkeynotes 4y ago
Is that £10k for a mini split system? I'm not sure how many homes would need to spend that much. The UK is full of small flats and 2 up/down places that could rely on maybe one or two splits, Google shows that a decent setup would be about £2k plus installation (two splits each at £1k inc tax). Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain. > There's also the consideration of additional costs due to lower running temperature which often necessitate larger radiators. I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration. Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home.
- Jochim 4y ago
  > Is that £10k for a mini split system? It was 2021 when I last last looked into it but I recall that 10k was the list price of the cheapest air source heat pump that wouldn't result in a net increase in energy bills. I don't believe it included installation or any other associated costs. > Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain. It's almost unheard of for UK homes to have any sort of cooling installed. > I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration. UK homes are mainly heated with hot water radiators in each room; typically by an on demand gas combi-boiler that also handles hot water. Heat pump installations in the UK typically heat a hot water tank[0] that provides domestic hot water and heats the radiators. Due to poor insulation the gas central heating systems typically run at around 60-80c. Heat pumps here usually heat the water to around 40c. This will often require replacing existing radiators that were installed expecting ~70c flow temperature with oner that can disperse more heat into the room. It can also involve additional insulation. > Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home. Indeed, heat pumps are a sensible choice for most new build homes in the UK as well. They typically have much better insulation and are therefore less affected by the low flow temperature. The costs involved in retrofitting anything older than 10, maybe 20 years old were. [0] https://solarthermuk.co.uk/wp-content/uploads/2020/12/air_source_heat_pump.jpg https://solarthermuk.co.uk/wp-content/uploads/2020/12/air_so...
  - monkeynotes 4y ago
    If you are looking at air to water heat pumps you will certainly be looking at much more expensive installs. Mini splits are way cheaper and don't require hooking up to the gas hot water system which can simply be retired to backup heat source. And yeah, cooling is not a thing in the UK, my point is folks are definitely going to be looking toward that given the summers people have been having, increase heating costs will make mini splits a double win. No brainer to me and I bet mini splits will be in limited supply this summer in Europe.