Heat pumps vs Gas boiler ?

Joined
4 Aug 2007
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Wilds of suffolk
Solar heating doesn't work very well on cold winter nights though does it!
So in effect the main times when most people would want most heating (air/water) would be back to the grid, immersion heating in effect. Whelp at that cost.

Again we are back to one size doesnt fit all

AC type units by nature of being air exchangers do have issues in the cold temps, I have seen this myself where my unit at work froze up and too time to sort itself out.
A couple of hours in it was fine, it had heated my office and just topping up was fine. Everyone had similar issues and started setting them to come on 2 hours before they arrived so their office wasn't freezing and the AC/heater not working well.

Ground source avoids all those issues but from what I can tell its (without going massive) far better to provide background levels and top up as necessary rather than switch it on and expect rapid heating like we do with gas.

If we go nuclear generation massive maybe it wouldn't be too bad. But future energy mix doesn't look like it would support domestic consumption going to mainly in effect immersion very well at all!
 
Associate
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UK
Solar heating doesn't work very well on cold winter nights though does it!
So in effect the main times when most people would want most heating (air/water) would be back to the grid, immersion heating in effect. Whelp at that cost.

Again we are back to one size doesnt fit all

AC type units by nature of being air exchangers do have issues in the cold temps, I have seen this myself where my unit at work froze up and too time to sort itself out.
A couple of hours in it was fine, it had heated my office and just topping up was fine. Everyone had similar issues and started setting them to come on 2 hours before they arrived so their office wasn't freezing and the AC/heater not working well.

Ground source avoids all those issues but from what I can tell its (without going massive) far better to provide background levels and top up as necessary rather than switch it on and expect rapid heating like we do with gas.

If we go nuclear generation massive maybe it wouldn't be too bad. But future energy mix doesn't look like it would support domestic consumption going to mainly in effect immersion very well at all!
Yes really the fact is we all need a mix of solutions, not just one, but then it gets crazy expensive...if it isn't crazy expensive enough for just one solution.

Course you know the real issue is that somehow the government are managing to pass the responsibility for this on to the public. For decades all political parties have managed to kick the ball down the road, band-aiding the problem rather than implementing a proper solution. We really do need to shut all the different voices off and implement a sensible set of measures so the public can just go about their business without worrying about all this.
 
Soldato
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Portsmouth
and then you've got a very expensive running electic boiler with none of the benefits. Solar + Electric Boiler makes zero sense to me in this country, should just stick with Gas at 1/4 to 1/5th the price and similar efficiency, only benefit of ASHP or AC is that they are 3.5-4 times as efficient as a gas boiler so the electric to gas costs sort of balance out.
 
Joined
4 Aug 2007
Posts
15,176
Location
Wilds of suffolk
Yes really the fact is we all need a mix of solutions, not just one, but then it gets crazy expensive...if it isn't crazy expensive enough for just one solution.

Course you know the real issue is that somehow the government are managing to pass the responsibility for this on to the public. For decades all political parties have managed to kick the ball down the road, band-aiding the problem rather than implementing a proper solution. We really do need to shut all the different voices off and implement a sensible set of measures so the public can just go about their business without worrying about all this.

True, money no object I would install a ground sourced heat pump to replace my GFCH, and add a level of "instant" AC type units to provide additional heating/cooling as required.
Based on the theory if ground sourced backup can keep it relatively stable in low teens 24/7 then topping up to nice comfortable levels on demand would be quick and relatively cheap.

I would install solar covering my whole roof and a battery sized system to match somewhere close to 90% of peak real world production of those panels (the additional cost for the 10% of peak for a short part of the year being highly uneconomic)
Although even then maybe going higher might work based on demand. Its super hard to predict without having real world usage costs for the heat sources when not having solar generation active.

Plus of course enough capacity to mainly heat the water by solar (either directly on indirectly depending on the heating time)

I'm guessing you would probably rocket to around £100k for that for my house. Plus it would be dubious for 4 months of the year (Nov-feb), plus I would almost certainly face planning issues on placement of enough heat exchangers, and finally thats assuming I could grid tie it as backup and not forced to go off grid as i couldnt get permission to tie in something that large.
The minor issues ;) aside. Should just about be able to see no bills for the majority of the year.
On the other hand, adding £100k to my house cost would still net me a half decent improvement in my house, where I live probably gaining me some land, another bedroom or so, and some more facilities such as larger garage etc
Oddly adding £100k to my house value via moving to similar to above would probably genuinely give me the capacity to install a system like I mention above and really go off grid.
(Maybe having a decent size diesel generator (something like 6KVA) as backup for the deep winter.
 
Caporegime
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Berks / Moscow
3:1 ratio at best for energy out: energy in. More likely 2.2-2.5:1

28p/kWh for electric. 7p for gas, let’s say 8p to make up for losses. Gas is cheaper to heat you house
 
Soldato
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4,251
Ahh good, you're working asumptions of a standard electricity tarif being used for a heat pump, and very low SCOP figures.

SCOP of modern heat pumps is around 3.8:1 at 50c flow rates even at sub zero temperatures, and heatpump tarif rates where I live are 13.04p per k/wh.
 
Caporegime
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How do you get lower energy rates ? I’m maybe assuming you would pay the energy cap rate.

I think the maths could make sense like in your case. I would expect the ROI is long ? But if you are running 50C temps then all your rads etc need changing and you the noise can sometimes be an issue
 
Soldato
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4,251
The heat pumps have their own meter charged charged at a different rate, where I live that's 13.04p per kwh (Guernsey).

We're doing a full renovation so would have had the costs of all new heating system regardless of which direction we went, we're going the UFH route which are ideal for heat pumps from our understanding.
 
Caporegime
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Yes so makes sense. I thought we were talking about U.K. prices. Hence I still stand by my comments for U.K. houses and the OP question.

And for reasons you state it doesn’t work on a retrofit or replacement for a boiler in many cases. Ideal for new build with UFH
 
Associate
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I am not really that convinced about heat pumps which is kinda odd since I make them. Well, I work in the R&D deptartment for a company that does.

The problem is that they just move heat from one place to another, and that's not entirely great in very cold weather, because there isn't that much heat to move. They get less efficient the colder the weather gets. On top of that, in a humid country like ours, they tend to ice up rapidly, and then have to spend time reversing the flow of heat to defrost themselves. On top of that you have huge installation costs and very high costs should it break down at any point. Also they don't produce temperatures that are particularly useful in a domestic heating situation. In short, they don't get very hot. They are supposed to generate heat at a cost of about 1:3 but in practice I very much doubt you will achieve that.

To me a much more preferable way to go is solar.

Is it true that last winter a lot of air source heat pumps broke down due to freezing or whatever and owners were waiting for up to four months for repair? No spares for the new tech and a shortage of skilled engineers to fix them apparently. The owners had to fall back on portable electric heaters. If only irony kept people warm.

Something to be wary about ground source heat pumps is because the system extracts heat from the ground there is a risk of creating a 'permafrost' on your land and the efficiency of the system drops significantly. The ground loops absorb the heat, the sun replaces that heat. If for some reason that heat is not replaced in the ground (poor summer, tree cover, too much heat taken previously) then the ground gets colder again in the winter and the cycle repeats.
 
Don
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Spalding, Lincolnshire
Is it true that last winter a lot of air source heat pumps broke down due to freezing or whatever and owners were waiting for up to four months for repair?
Sounds like sensationalism to me.

My ASHP worked absolutely fine over winter. Yes it's less efficient at lower temperatures, but the temperature would have to be far lower than even a "bad" UK winter, for them to stop working entirely
 
Associate
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Northampton
I am not really that convinced about heat pumps which is kinda odd since I make them. Well, I work in the R&D deptartment for a company that does.

The problem is that they just move heat from one place to another, and that's not entirely great in very cold weather, because there isn't that much heat to move. They get less efficient the colder the weather gets. On top of that, in a humid country like ours, they tend to ice up rapidly, and then have to spend time reversing the flow of heat to defrost themselves. On top of that you have huge installation costs and very high costs should it break down at any point. Also they don't produce temperatures that are particularly useful in a domestic heating situation. In short, they don't get very hot. They are supposed to generate heat at a cost of about 1:3 but in practice I very much doubt you will achieve that.

To me a much more preferable way to go is solar.
I know a British Gas engineer who installs boilers and another Plumber who services all boilers, both said the heat pumps are not going to be the way forward. The BG guy said he’s own boiler needs replacing in the next year then he’ll install another new one in the year before they’re banned if need be but he is confident hydrogen boilers will be the number one choice
 
Soldato
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4,251
Yes so makes sense. I thought we were talking about U.K. prices. Hence I still stand by my comments for U.K. houses and the OP question.

And for reasons you state it doesn’t work on a retrofit or replacement for a boiler in many cases. Ideal for new build with UFH
I believe the UK have heat pump tariffs too as an option, a quick Google indicates they can be found.

Long term however, anyone with a heat pump should be looking in to solar powering it, given the relatively low energy in required vs energy out, it's certainly our long term plan, especially for the 24kw model.
 
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