The Lemon Fool

The Government seems intent on removing gas boilers in the long run. Much of what I've read implies they are intent on electric heating or ground/air source. DAK what the approach would be for those of us with wet-loop underfloor heating. Will it be using electric to heat/circulate the water?

Best go here, where there is lots of technical discussion on all forms of renewable energy :-
https://www.navitron.org.uk/forum/index.php

The first law of thermodynamics will always apply and if many households in the same area use air or ground source, individual efficiencies will suffer.

https://www.navitron.org.uk/forum/index ... #msg350600

neversay wrote:The Government seems intent on removing gas boilers in the long run. Much of what I've read implies they are intent on electric heating or ground/air source. DAK what the approach would be for those of us with wet-loop underfloor heating. Will it be using electric to heat/circulate the water?

It is most likely that the combi-boiler manufacturers will just switch over the making ASHPs that are drop-in replacements for existing combi boilers. That would supply the existing wet loop in most British properties. So as the combis reach replacement date on a house-by-house basis they just get changed out. That is my personal opinion, and is also the opinion of the folks I know who are in that game (some of whom are at the relevant manufacturers).

regards, dspp

I believe that ASHP provide different temperature water to gas boilers, so there may be a need to re-scale the pipework and radiators to handle the different flow/heat characteristics.

https://great-home.co.uk/air-source-hea ... s-boilers/

"Heat pumps work most efficiently when delivering a flow of water at around 35°C, rather than the 60°C typically delivered from a gas boiler. As the water temperature is lower, radiators need to be larger than those used for gas boilers. Underfloor heating, which needs a much lower temperature anyway, is a good option if it can be installed as part of the concrete floor slab. "

Different solutions will suit different buildings on an individual basis. For some, community/area-wide schemes make a lot of sense.

We'll also need someone capable of doing the work. For my house, a water-source heat pump drawing heat from the river (together with a big tank) would be ideal[1], but I can't find anyone who'll quote for supplying/installing it. Ground or air source would be pretty useless here.

[1] Better still as a shared scheme between neighbours and me serving all five houses in the building, with economies of scale.

JohnB wrote:
I believe that ASHP provide different temperature water to gas boilers, so there may be a need to re-scale the pipework and radiators to handle the different flow/heat characteristics.

Whilst generic gas-central-heating radiator-size might well be an issue when compared to ASHP requirements (and it is..), I think the bigger issue is the poor insulation properties of the bulk of UK housing.

The lower running temperatures of ASHP systems means that they are only really useful in very well-insulated homes, as the general heat loss in older houses is too fast for a low-temperature ASHP system to raise the temperature of sufficiently well, and as such I think that the costs involved with an ASHP system-installation and any existing system-modification itself are likely to be only part of any overall costs, given the wider home-insulation requirements on top of that...

Of course that's likely to improve with new-builds, which will no doubt transition through any gas-central-heating phase-out in a much smoother way, but for existing housing stock where the legacy insulation and heat-retaining properties are much, much poorer, such a transition away from gas central-heating has the potential to be much more painful, depending of course on how the transition is likely to be subsidised etc....

Cheers,

Itsallaguess

Many thanks for your kind replies. We have a PHEV vehicle and are planning a new 'green' house extension for next year. On both fronts, the number of choices of technology, and optimum investment, seems to get ever more complex.

neversay wrote:Many thanks for your kind replies. We have a PHEV vehicle and are planning a new 'green' house extension for next year. On both fronts, the number of choices of technology, and optimum investment, seems to get ever more complex.

Actually I think the winners are becoming clearer:
- domestic solar PV (if you have a suitable roof);
- insulate (unless there is a die-in-a-ditch reason not to);
- BEV;
- ASHP when your combi fails;

The lower ASHP circulating temperatures are not a problem provided you insulated. If not you are stuffed.

regards, dspp

Totally agree but suspect current ASHP design/ development for domestic properties is not yet at a stage where they are acceptable for cost, size and straightforward exchange with gas boilers.

richlist wrote:Totally agree but suspect current ASHP design/ development for domestic properties is not yet at a stage where they are acceptable for cost, size and straightforward exchange with gas boilers.

The ASHP sits outside, so gives you more space where the gas boiler used to be. However, it has a large hot water storage cylinder inside, so you need to find space for that if replacing a combi-boiler.

The fact you already have underfloor heating would make you the ideal candidate for an Air Source Heat Pump. We have just installed one in our large Victorian house, in conjunction with a gas boiler - our solution is known as a bivalent solution - the heat pump heats water to around 50C and provides effective heating to radiators. In the event that the weather is very cold, the heat pump passes control to the boiler which then comes on and provides heating instead, Our gas usage is now a fraction of what it used to be and overall heating costs are lower.

Steve.

dspp wrote:Actually I think the winners are becoming clearer:
- domestic solar PV (if you have a suitable roof);

Many of us don't.

- insulate (unless there is a die-in-a-ditch reason not to);

Easier said than done in a listed building or conservation area.

- BEV;

Huh?

- ASHP when your combi fails;

I'm intrigued. Air is not an ideal source: not so much specific heat to be had, issues of condensation and freezing, and noisy pumps. Surely the return on energy used to power the pump is fairly marginal?

... which is why I'd much rather install a river-water-source heat pump, and draw on something better than air. Along with thick stone walls, and possible planning issues with a b***** great pump mounted on the outside of the house!

UncleEbenezer wrote:

dspp wrote:Actually I think the winners are becoming clearer:
- domestic solar PV (if you have a suitable roof);

Many of us don't.

- insulate (unless there is a die-in-a-ditch reason not to);

Easier said than done in a listed building or conservation area.

- BEV;

Huh?

- ASHP when your combi fails;

I'm intrigued. Air is not an ideal source: not so much specific heat to be had, issues of condensation and freezing, and noisy pumps. Surely the return on energy used to power the pump is fairly marginal?

... which is why I'd much rather install a river-water-source heat pump, and draw on something better than air. Along with thick stone walls, and possible planning issues with a b***** great pump mounted on the outside of the house!

1. BEV = battery electric vehicle.

2. No roof = pay extra to buy in your electricity for your BEV ..... worth trying hard to get solar PV and make as much of your own power as possible.

3. Fully aware of listed bldng & conservation zones. I have solar installs on two such, one listed (my GF's), one conservation (mine). Ditto for extensive insulation. When needs must, ingenuity overcomes

4. ASHP typically runs at COP of 3:1 or 4:1. There are people on this board doing that for real in the UK now, and these are mainstream mass market appliances in high volume manufacture and installation now. Personally I expect my boiler to die in about 10-years and I will rotate across to ASHP then. And because I was planning ahead I retained my hot water storage cylinder.

5. If you go for a 'special' such as a WSHP then you will forever be trying to find 'special' installer/maintainers/spares to service your needs ...... That is a good reason to stay with mainstream kit imho. Unless you are talking of a huge ancestral pile with a trained staff who can keep all manner of things going, but I don't think Aunty Betty hangs out on TLF

all imho

regards, dspp

Thanks for the detailed reply.

dspp wrote:2. No roof = pay extra to buy in your electricity for your BEV ..... worth trying hard to get solar PV and make as much of your own power as possible.

No BEV either.

Have roof, but it's heavily shaded by a high bank, north-facing slope, and lots of trees. I actually have much more light on my north (river-facing) side.

3. Fully aware of listed bldng & conservation zones. I have solar installs on two such, one listed (my GF's), one conservation (mine). Ditto for extensive insulation. When needs must, ingenuity overcomes

Some scope for eventual projects there. One I definitely want is to replace/update at least the river-facing windows.

5. If you go for a 'special' such as a WSHP then you will forever be trying to find 'special' installer/maintainers/spares to service your needs ...... That is a good reason to stay with mainstream kit imho. Unless you are talking of a huge ancestral pile with a trained staff who can keep all manner of things going, but I don't think Aunty Betty hangs out on TLF

I'm trying to think ahead here. If gas gets abandoned or marginalised, alternatives get a boost. Water source will always be a minority sport for obvious reasons, but I'd expect it in due course to pass a threshold where an adequate proportion of fitters/maintenance folks get the training.

Trouble right now is, I have a gas boiler on its last legs, and the only feasible replacement seems to be a new gas boiler

I've got 4kw solar panel system which works well, but of course most electricity is generated in the summer not the winter.

As for the boiler ours is oil. They haven't mentioned banning those (yet!).

Heat pumps are no doubt wonderful, but they all use electricity so that is going to be yet another big increase in electricity demand.

Our air source heat pump has a COP of about 3.2 and we get that in practice. So for every kW of electricity we get slightly more than 3kW of heat generated. If you know your bills and the efficiency of your gas boiler then you should be able to work out whether your costs will be lower. Ours are marginally lower, without considering the RHI payments. It isn't particularly noisy - any more so than a condensing boiler flue outlet, which can make some low level noise. It is however a reasonably large box situated outside the house and requires a concrete plinth. There's also an indoor unit and hot water cylinder.

SMarkus wrote:If you know your bills and the efficiency of your gas boiler then you should be able to work out whether your costs will be lower.

For myself I've no doubt whatsoever gas is cheaper. Even with an old, inefficient boiler. Though a smart electricity tariff (cheap overnight) might affect that.

But that's not really the measure that matters. Even if you focus solely on cost, what matters is the cost over the lifetime of whatever you install. And with political winds more volatile than the storm, that's not something I'd care to predict.

UncleEbenezer wrote:

SMarkus wrote:If you know your bills and the efficiency of your gas boiler then you should be able to work out whether your costs will be lower.

For myself I've no doubt whatsoever gas is cheaper. Even with an old, inefficient boiler. Though a smart electricity tariff (cheap overnight) might affect that.

But that's not really the measure that matters. Even if you focus solely on cost, what matters is the cost over the lifetime of whatever you install. And with political winds more volatile than the storm, that's not something I'd care to predict.

Roughly speaking gas is 5p/kWh and electric is 15p/kWh.

So running an ASHP at a COP of 3.2:1 is giving you heat at 15p/3.2 = 4.6p/kWh . So running an ASHP from grid electricity is already cost parity with a gas boiler.

In my case, if I were to fit a 10kWh battery bank (which I expect to do in about 5-10 years time), then my spare electricity would give me free heat for 6-months of the year. By the time I have finished working through my insulation projects I think that will be 8-months of the year for free heat. And then I can see how to (neatly) put another 2kW of solar on my shed roofs and I will be an importer for only 2-months of the year, and an exporter for 6-months of the year, and in rough balance for about 4m. (I'm making a few estimates about the future, but the path seems pretty clear). And I am an absolutely bog-average Victorian terraced house that is very typical of much of the UK housing stock.

On my GF's humongous pile it is a longer journey, but in general terms larger properties with land give many more opportunities, though there are of course costs, just as with any large pile.

regards, dspp

OP here and just about to head off somewhere sunny for a couple of weeks but wanted to thank everyone for the enlightening responses and useful advice to factor into my plans.

The Gas industry in the UK and Europe currently have trials underway injecting Biogas and also Hydrogen produced by Renewable Energy sources into the gas network. Both are currently being added to standard natural gas in various trials in limited quantities without the need for major changes to the gas boiler. Hydrogen & Biogas have the advantage that it can be stored after production from a Renewable Energy source. A complete replacement of natural gas by Renewable sourced Hydrogen would require large a changeover programme similar to what happened in the 60's & 70's.