hmmmmmm room temperature

Strummer22

EssexHebridean said:

It’s worth underlining also that ASHPs are going to be more efficient at increasing the internal temperature than GCH or former standard forms of electric heating where you’d presumably need 5kW input to get that same 1° increase? 

More efficient is correct, but not necessarily cheaper compared to gas central heating. At the moment electricity (~34p/kWh) is just over 3x more expensive than gas (~10.3p/kWh). A heat pump would need to produce about 3.3 kWh of heat output per kWh of electricity input to break even compared to gas, assuming the same efficiency of the rest of the system.

Obviously, a heat pump easily beats direct electric heating on efficiency, and both gas and heat pumps beat direct electric heating on price.

Astria

Strummer22 said:

EssexHebridean said:

It’s worth underlining also that ASHPs are going to be more efficient at increasing the internal temperature than GCH or former standard forms of electric heating where you’d presumably need 5kW input to get that same 1° increase? 

More efficient is correct, but not necessarily cheaper compared to gas central heating. At the moment electricity (~34p/kWh) is just over 3x more expensive than gas (~10.3p/kWh). A heat pump would need to produce about 3.3 kWh of heat output per kWh of electricity input to break even compared to gas, assuming the same efficiency of the rest of the system.

Air-to-water heat pumps are pretty good at maintaining temperature (assuming they are installed and configured correctly), but typically quite poor at increasing the temperature due to there low flow temperatures. The higher the flow rate the lower they typically perform.

Air-to-air heat pumps can seem more efficient because they can produce an instant result in the sense of warm air being blown around, rather than convected air warming the room, but if people are not in their air flow they can seem less efficient. 

I have a A2A heat pump downstairs which only draws about 500W, which is perfect for spring and autumn as it can run off solar power, but its not very good in the depths of winter.

alibean121

jvjack said:

The 900k houses may be being heated to 23 degrees in every room night and day so it might be enough to warm up the roofs more than if at 18 degrees.

The direction of the roof plays a big role as well. My row of terraces, none of the houses keep their frost on the roof once the sun is up. There’s another terrace of identical houses at right angles that have frost visible a lot of the day. 

jvjack

Same where i live alibean121.  I watched and let the sun come round the house this saturday morning to clear the frost on my van windscreen before going to supermarket. Took about 20 mins.
Could be the heat loss though. Or those tiles or the sun. Or they use the loft/attick as rooms.

Mstty

Strummer22 said:

EssexHebridean said:

It’s worth underlining also that ASHPs are going to be more efficient at increasing the internal temperature than GCH or former standard forms of electric heating where you’d presumably need 5kW input to get that same 1° increase? 

More efficient is correct, but not necessarily cheaper compared to gas central heating. At the moment electricity (~34p/kWh) is just over 3x more expensive than gas (~10.3p/kWh). A heat pump would need to produce about 3.3 kWh of heat output per kWh of electricity input to break even compared to gas, assuming the same efficiency of the rest of the system.

Obviously, a heat pump easily beats direct electric heating on efficiency, and both gas and heat pumps beat direct electric heating on price.

You forgot to calculate that boilers are not 100% efficient.

If you adjust for an average 90% efficiency which is very generous the cop required is 3kwh output to match.

As an example our 7 and a half year old ASHP won't have lost any efficiency and still producing a yearly SCOP of over 3. Not sure this would be the same for a gas boiler.

Just some food for thought but I am certainly glad we didn't have to pay to have this out in and bought the house as second owners. That's the main difference there is no return on investment it's still very much a "green" choice for those that can afford it.

maxmycardagain

well we are leaving heating on 24/7 and setting the thermostat at 20 daytime and 15 night time, the cost seems to be acceptable, lets hope 2023 is a hot year...