5 ms·

My mum has a heat pump install which she hates for being lukewarm all the time. It feels underspecced! When I've looked at one for my home to replace a 24kW ga

My mum has a heat pump install which she hates for being lukewarm all the time. It feels underspecced! When I've looked at one for my home to replace a 24kW gas boiler, all I can find is 14kW kits. Am I missing something? Can I not match the output of a big gas boiler?

gymbeaux 3y ago
I would look at BTUs rather than wattage and o would expect an equivalent heat pump system to use less electricity.
- bryanlarsen 3y ago
  Wattage on a heat pump or furnace or boiler is a measure of heat output, not of energy input.
photon_rancher 3y ago
You can, but central units aren’t great right now. Mini-splits are much better. Price is lower, cheaper to install, regulation between rooms is more even, and you can turn off unused rooms to save energy. Not sure why the market has moved this way but it is what it is. That unit probably is underspeced
- Mountain_Skies 3y ago
  Mini-splits are functionally excellent but have a difficult time with the Wife Factor. So far most of the decorative "solutions" are rather poor. I'm sure over time, as they become more popular, people will come up with ideas for how to work them into the home's interior design, but for now, many find them too utilitarian in appearance.
- cillian64 3y ago
  I was looking into this and one factor is that you still need hot water. So with mini-splits your options are either resistive water heating or having a gas boiler as well. I haven’t seen any systems which do mini-splits and also heat a hot water tank.
  - guruz 3y ago
    Heat Pump Water Heater. You can put it next to high end computer to suck its heat in :-) https://carbonswitch.com/heat-pump-water-heater-buyers-guide/ https://carbonswitch.com/heat-pump-water-heater-buyers-guide...
sdflhasjd 3y ago
24kW is basically the peak when it's doing instant hot-water for the taps. You shouldn't need that to heat a home. You're right, it can't match the _peak_ output, but the whole system is designed so this isn't necessary. With a "traditional" combi-boiler, it will turn on occasionally to heat the water in the central heating system, and continue to pump it around. When you need hot water, it switches over the heat-exchanger to directly heat the incoming water and this is when it will ramp up and burn the most gas (24kW+). For an air-to-water heat pump system, the system will be on almost continually, but will heat the water to a lower temperature, the peak power output is less, but it averages out the same. For hot water, the system will heat a storage cylinder. One of the catches here is that's it not always an easy retrofit as the lower water temperature can necessitate larger radiators.
morsch 3y ago
She might need larger radiators. https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-for-a-heat-pump/ https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-f...
- mattbee 3y ago
  Maybe, but it's not a conversion. The house was built new with heat pumps.
  - ZeroGravitas 3y ago
    Might be worth checking how they are using it. If they're used to gas heating in a less well insulated home they may swich it off until they need it, whereas in a well insulated home with a heat pump you want it on basically all the time. edit: In-depth geeky video on this: https://www.youtube.com/watch?v=kGs_biFA87Q https://www.youtube.com/watch?v=kGs_biFA87Q
Loic 3y ago
You need to size the heat pump based on the gas consumption over a year, not the instant supply. Here is a very good explanation: https://protonsforbreakfast.wordpress.com/2022/04/05/what-size-heat-pump-do-i-need-a-rule-of-thumb/ https://protonsforbreakfast.wordpress.com/2022/04/05/what-si...

gymbeaux 3y ago

I would look at BTUs rather than wattage and o would expect an equivalent heat pump system to use less electricity.

bryanlarsen 3y ago
Wattage on a heat pump or furnace or boiler is a measure of heat output, not of energy input.

photon_rancher 3y ago

You can, but central units aren’t great right now. Mini-splits are much better. Price is lower, cheaper to install, regulation between rooms is more even, and you can turn off unused rooms to save energy. Not sure why the market has moved this way but it is what it is. That unit probably is underspeced

Mountain_Skies 3y ago
Mini-splits are functionally excellent but have a difficult time with the Wife Factor. So far most of the decorative "solutions" are rather poor. I'm sure over time, as they become more popular, people will come up with ideas for how to work them into the home's interior design, but for now, many find them too utilitarian in appearance.
cillian64 3y ago
I was looking into this and one factor is that you still need hot water. So with mini-splits your options are either resistive water heating or having a gas boiler as well. I haven’t seen any systems which do mini-splits and also heat a hot water tank.
- guruz 3y ago
  Heat Pump Water Heater. You can put it next to high end computer to suck its heat in :-) https://carbonswitch.com/heat-pump-water-heater-buyers-guide/ https://carbonswitch.com/heat-pump-water-heater-buyers-guide...

sdflhasjd 3y ago

24kW is basically the peak when it's doing instant hot-water for the taps. You shouldn't need that to heat a home. You're right, it can't match the _peak_ output, but the whole system is designed so this isn't necessary. With a "traditional" combi-boiler, it will turn on occasionally to heat the water in the central heating system, and continue to pump it around. When you need hot water, it switches over the heat-exchanger to directly heat the incoming water and this is when it will ramp up and burn the most gas (24kW+). For an air-to-water heat pump system, the system will be on almost continually, but will heat the water to a lower temperature, the peak power output is less, but it averages out the same. For hot water, the system will heat a storage cylinder. One of the catches here is that's it not always an easy retrofit as the lower water temperature can necessitate larger radiators.

morsch 3y ago

She might need larger radiators. https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-for-a-heat-pump/ https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-f...

mattbee 3y ago
Maybe, but it's not a conversion. The house was built new with heat pumps.
- ZeroGravitas 3y ago
  Might be worth checking how they are using it. If they're used to gas heating in a less well insulated home they may swich it off until they need it, whereas in a well insulated home with a heat pump you want it on basically all the time. edit: In-depth geeky video on this: https://www.youtube.com/watch?v=kGs_biFA87Q https://www.youtube.com/watch?v=kGs_biFA87Q

Loic 3y ago

You need to size the heat pump based on the gas consumption over a year, not the instant supply. Here is a very good explanation: https://protonsforbreakfast.wordpress.com/2022/04/05/what-size-heat-pump-do-i-need-a-rule-of-thumb/ https://protonsforbreakfast.wordpress.com/2022/04/05/what-si...