ASHP results

[nowty]

Last year after I fitted my A2A HPs during the summer, it first froze up on 8th Dec.
https://camelot-forum.co.uk/phpBB3/view ... 220#p24356

[Krill]

You burn the gas in a CCGT to make electricity for the heat pump.

We are ridiculously good at burning gas on site for heat, 90% is efficiency easy. So 1 unit of gas becomes 0.9 units of heat.

Even a crap heat pump turns 1 unit of electricity into 3 units of heat.

A CCGT powerplant gets 60% efficiency. So 1 unit of gas makes 0.6 units of electricity.

So, out 1 unit of gas made 0.6 units of electrical energy from the power station become 0.6*3=1.8 units of useful heat in the heat pump. Magically more useful energy than the gas itself had and superior to the, ridiculously good really, boiler.

If only we had some kind of reliable, large scale electrical base load power plant that didn't use gas or coal.

Thinking this through, I think there are edge cases where it gets more complicated. PLaying devils advocate, because I do not disagree with your general point.

• Houses owned by single people who area only in them for brief time periods (shift workers on 12 hour shifts, come home, eat, shower, bed, up out to work).
• Houses with overly large water tanks for the generaly usage. Think 4 bed houses with two occupants, the should the water tank fit the house, or the use? And what about when the occupants then have a variable water use ie three days a week oerson A showers at the gym? The same volume of water in the tank has to be heated to the same temperature for person B.
• Houses with heat coming from solid fuel burners for house warming - building standards require ventilation, how would this mesh with heat pump requirements?

I have just had a smart meter fitted to get onto Octopus Flux, and now I can see how much gas I'm using for DWH for baths and showers only (no house heating) and match it up to daily use, it feels that a heat pump might not actually justify the cost but an electric boiler actually might do, provided I expanded the battery storage...but that runs completely contrary to the main point.

I think there is more to the story. Personally, I will probably get an AHSP quote in a couple of years (when the boiler is closer to the end of the warranty) and see what they say. I don't have any room for a plant room, and no where that it can be sited outside either, but hey, if I have to have a heat pump, let them sort it out *shrug*

[Stinsy]

Thinking this through, I think there are edge cases where it gets more complicated. PLaying devils advocate, because I do not disagree with your general point.

• Houses owned by single people who area only in them for brief time periods (shift workers on 12 hour shifts, come home, eat, shower, bed, up out to work).
• Houses with overly large water tanks for the generaly usage. Think 4 bed houses with two occupants, the should the water tank fit the house, or the use? And what about when the occupants then have a variable water use ie three days a week oerson A showers at the gym? The same volume of water in the tank has to be heated to the same temperature for person B.
• Houses with heat coming from solid fuel burners for house warming - building standards require ventilation, how would this mesh with heat pump requirements?

I have just had a smart meter fitted to get onto Octopus Flux, and now I can see how much gas I'm using for DWH for baths and showers only (no house heating) and match it up to daily use, it feels that a heat pump might not actually justify the cost but an electric boiler actually might do, provided I expanded the battery storage...but that runs completely contrary to the main point.

I think there is more to the story. Personally, I will probably get an AHSP quote in a couple of years (when the boiler is closer to the end of the warranty) and see what they say. I don't have any room for a plant room, and no where that it can be sited outside either, but hey, if I have to have a heat pump, let them sort it out *shrug*

Those are all good questions!

There are loads of use cases where the standard MCS enormo DHW tank kept perpetually at 45℃ and heated to 60℃ once a fortnight is not the most optimal solution. You might have a large home with infrequently-used guest bedrooms. Having an electric shower in the guest bedroom and a small DHW tank is a better solution.

The same goes for a house that is unoccupied for long periods (eg young professionals working long hours). Here a standard MCS low-and-slow 24/7 A2W heat pump is a poor solution. A2A units or even IR panels are much better in this situation.

The point is that the way MCS installers are forced to design and install systems is poor for a lot of use cases.

If you have a log burner then piping external air directly to the burner is a better solution than having a vent on the other side of the room.

[nowty]

Another point I would add to Swwils calculation is that last winter Dec/Jan/Feb the UK averaged 50%+ zero carbon leccy which is more than halfway to a reliable large scale electrical base load that doesn't use gas or coal.

You can check the national grid reports,
https://www.nationalgrideso.com/electri ... city-stats

Dec 51%
https://www.nationalgrideso.com/documen ... 6/download

Jan 56%
https://www.nationalgrideso.com/documen ... 6/download

Feb 47%
https://www.nationalgrideso.com/documen ... 1/download

[Swwils]

You burn the gas in a CCGT to make electricity for the heat pump.

We are ridiculously good at burning gas on site for heat, 90% is efficiency easy. So 1 unit of gas becomes 0.9 units of heat.

Even a crap heat pump turns 1 unit of electricity into 3 units of heat.

A CCGT powerplant gets 60% efficiency. So 1 unit of gas makes 0.6 units of electricity.

So, out 1 unit of gas made 0.6 units of electrical energy from the power station become 0.6*3=1.8 units of useful heat in the heat pump. Magically more useful energy than the gas itself had and superior to the, ridiculously good really, boiler.

If only we had some kind of reliable, large scale electrical base load power plant that didn't use gas or coal.

Thinking this through, I think there are edge cases where it gets more complicated. PLaying devils advocate, because I do not disagree with your general point.

• Houses owned by single people who area only in them for brief time periods (shift workers on 12 hour shifts, come home, eat, shower, bed, up out to work).
• Houses with overly large water tanks for the generaly usage. Think 4 bed houses with two occupants, the should the water tank fit the house, or the use? And what about when the occupants then have a variable water use ie three days a week oerson A showers at the gym? The same volume of water in the tank has to be heated to the same temperature for person B.
• Houses with heat coming from solid fuel burners for house warming - building standards require ventilation, how would this mesh with heat pump requirements?

I have just had a smart meter fitted to get onto Octopus Flux, and now I can see how much gas I'm using for DWH for baths and showers only (no house heating) and match it up to daily use, it feels that a heat pump might not actually justify the cost but an electric boiler actually might do, provided I expanded the battery storage...but that runs completely contrary to the main point.

I think there is more to the story. Personally, I will probably get an AHSP quote in a couple of years (when the boiler is closer to the end of the warranty) and see what they say. I don't have any room for a plant room, and no where that it can be sited outside either, but hey, if I have to have a heat pump, let them sort it out *shrug*

You need to remember that electricity price is pegged to gas and doesn't actually reflect the system costs. (Despite lots of very silly energy policy decisions.).

In ANY case it's just simply more efficient use of the gas, that might not be the most cost effective method for you. But really that's also other people's fault! Lol.

A big help would be no VAT on electric for heat pumps or maybe even no VAT slice for generators of such destined energy on a local pricing basis. You could call it the HIT (heat in tarrif), you could even multiply your HIT payment by your base SCOP.

I'm not a big fan of such downstream accounting ninja tricks though, as they just get gamed and those actually keeping the lights on struggle more, we should just make the base energy cost as cheap as possible.

[Swwils]

I wouldn't say 50% is more than halfway in this context since the next 50% is considerably, "physics isn't your friend" style harder.

Even Scotland in her grace starts to count exported wind as a % of its total, conveniently not mentioning the self consumption figure anymore.

[nowty]

I wouldn't say 50% is more than halfway in this context since the next 50% is considerably, "physics isn't your friend" style harder.

Even Scotland in her grace starts to count exported wind as a % of its total, conveniently not mentioning the self consumption figure anymore.

I agree its not practical to get to 100%, but maybe getting close to 75% by the end of the decade with increased renewables, storage and interconnectors.

Nowty Towers is already at 75% zero carbon including car transport.

50% of total energy used is my own solar and the other 50% is imported in winter of which 50%+ is zero carbon, probably more as I only import overnight.

And I'm not including any of the ripple renewable projects to offset.

[Swwils]

At least we haven't done like Germany where baseload doesn't exist but if it does exist we don't need it and if we do need it we're committed to doing it in just the dumbest way you've ever heard of.

[Stinsy]

You need to remember that electricity price is pegged to gas and doesn't actually reflect the system costs. (Despite lots of very silly energy policy decisions.).

In ANY case it's just simply more efficient use of the gas, that might not be the most cost effective method for you. But really that's also other people's fault! Lol.

A big help would be no VAT on electric for heat pumps or maybe even no VAT slice for generators of such destined energy on a local pricing basis. You could call it the HIT (heat in tarrif), you could even multiply your HIT payment by your base SCOP.

I'm not a big fan of such downstream accounting ninja tricks though, as they just get gamed and those actually keeping the lights on struggle more, we should just make the base energy cost as cheap as possible.

Let’s keep it simple!

However we could:
- Remove gas subsidies.
- Remove VAT from electricity.
- Cut the electricity standing charge.

[Joeboy]

I wouldn't say 50% is more than halfway in this context since the next 50% is considerably, "physics isn't your friend" style harder.

Even Scotland in her grace starts to count exported wind as a % of its total, conveniently not mentioning the self consumption figure anymore.

I agree its not practical to get to 100%, but maybe getting close to 75% by the end of the decade with increased renewables, storage and interconnectors.

Nowty Towers is already at 75% zero carbon including car transport.

50% of total energy used is my own solar and the other 50% is imported in winter of which 50%+ is zero carbon, probably more as I only import overnight.

And I'm not including any of the ripple renewable projects to offset.

Going on last years figures
7MWh PV, very little gets into grid
13.5 MWh electric bought from grid on Octopus
1.2 MWh gas bought from grid

21.7MWh of power consumed on site 94.5% of which is non ff generated and this includes 12,000 miles in EV.

How do I then factor in 5 cubic mtrs of self felled and solar processed logs for WBS?

Edit-read the thread through, answer found.

This may have been asked, how many kWh's of gas does it take to generate 1kWh of electricity. Happy to go up to GW scale if easier. I find the cop of ASHP's fascinating as well as the myriad apparent pro's & con's.

Depending on supplier contract and generation source the two above are interlinked. Apologies if already discussed, I've only skimmed the thread on phone. Will read in detail later today.