The move to heat pumps

michaels

Martyn1981 said:

I think this idea / article ticks a lot of boxes regarding this discussion, it even mentions the idea of changing the green levy on leccy to help address the cost comparison v's gas. Obviously mentions insulation and housing standards, and the hope that costs will fall, if installs rise.

Poorer households in UK should get free heat pumps, say experts

Households on low incomes should be supplied with free heat pumps in order to kickstart the market for low-carbon heating equipment and meet the UK’s climate targets, experts have told the government.

Heat pumps can currently cost thousands of pounds to install, but the more that are installed, the faster that cost is likely to come down. They are widely regarded as the best way to replace the UK’s gas boilers and reduce carbon dioxide emissions from homes.

More than 20 organisations representing builders and construction businesses, energy companies and civil society groups have signed an open letter calling for a “fair heat deal” that would ensure people on low incomes can gain access to heat pumps.

About 14% of the UK’s greenhouse gas emissions come from heating the UK’s poor housing stock, most of which is also draughty and energy inefficient. The group also called for insulation to be made available to people on low incomes.

The letter also called on ministers to remove environmental levies from energy bills, to ensure it is always cheaper to run a heat pump than a boiler, and for grants to all households not on low incomes, to ensure that the cost of a new heat pump is competitive with the cost of installing a new gas boiler.

The signatories also called for the removal of VAT on green home products and servicers, and for changes to stamp duty to reduce the cost of homes that have been fitted with low-carbon technology.

I could have got a free heat pump under the green deal but didn't go for it as the running cost premium was huge.  Heat demand seems to be based on unrealistic assumptions about not being at home 24/7 and using last century assumptions on bathing (not all of us get out the tin bath every Sunday night and take it in turns to use the same water).

Baxter100

I am not anti-heat pump by any means, but the mass widespread installation of heat pumps into UK homes will be a calamitous disaster.

Baxter100

I  wonder if it might just be easier and cheaper overall to just install direct acting electric heaters into people's houses instead?

It's difficult to forecast exactly but lets say the government removes the existing supplier charges on the electricity bill and subsidises it further to bring the cost of a unit of electricity to 10 p/kWh.

Looking at your typical 1930s semi detached house, gas boiler to radiators. Cavity wall insulation, 100mm loft insulation. Heat demand of 15,000kWh. 

Scenario 1 - Replacement Heat Pump

Gas boiler is removed and heat pump installed directly in its place. Existing radiators kept in place to save on costs so seasonal efficiency of system reduced to 200%. Cost to install heat pump £10,000.

Annual heating bill £750.

Total install and heating costs after 10 years - £17,500

Scenario 2 - Direct Acting Electric Heaters

Wet system removed and direct acting heaters installed in all rooms at cost of £3,000. Heaters operate at 100% efficiency.

Annual heating bill £1500.

Total install and heating costs after 10 years - £18,000

Once you factor in servicing costs, repairs and so on the heat pump probably even works out more expensive. And this is in an ideal scenario where the house is already well insulated, the radiators aren't replaced, and no further electric works need doing on the building.

Disclaimer

This is obviously a very simplified individual scenario, and there are a hundred considerations that will impact these figures. Electric prices, heat pumps installs coming down, government incentives etc etc.

Just an interesting discussion point that for some houses electric panel heaters could well be a more convenient and even cheaper option.

Martyn1981

Kinda get the feeling that you've rigged that example to get the costs closer. I'd have thought upgrading radiators where necessary, or some basic insulation measures would make more sense, and then use a COP closer to 300%.

You'd also have to consider the need to generate and supply 3x as much leccy.

Also, what about the DHW demand for households that 'enjoy' 12 baths/showers per day, how would they cope?

Reed_Richards

Baxter100 said:

Scenario 1 - Replacement Heat Pump

Gas boiler is removed and heat pump installed directly in its place. Existing radiators kept in place to save on costs so seasonal efficiency of system reduced to 200%. Cost to install heat pump £10,000.

Annual heating bill £750.

Total install and heating costs after 10 years - £17,500

Scenario 1b - Replacement Heat Pump with new radiators

Gas boiler is removed and heat pump installed directly in its place. Existing radiators replaced at a cost of £2000 so seasonal efficiency of system is 300%. Cost to install heat pump £10,000 and radiators £2,000, total £12,000

Annual heating bill £500.

Total install and heating costs after 10 years - £17,000

£2000 is a very pessimistic estimate of the cost of replacing the radiators but even so it pays off.

QrizB

I think you're all being a bit pessimistic saying that it will be £10k to install a heat pump.

If you look at swimming pool heat pumps (which don't qualify for RHI, so you don't get the added overheads, er, "value" of MCS paperwork) the pump itself is only £2k. Add another £2k for a replacement DHW tank plus a couple of day's work and I reckon you could get it done for £5k?

Martyn1981

Yep, I expect costs will fall over time, and in Baxter's example we also have to consider the ginormous cost of subsidizing all leccy, or even if just all domestic leccy then that's probably ~£15bn pa. Plus the enormous increase and waste of leccy if the unit cost is reduced.

[Estimate based on 35% of an increased annual consumption of ~600TWh, and 7p/kWh or £70/MWh subsidy.]

Baxter100

Martyn1981 said:

Kinda get the feeling that you've rigged that example to get the costs closer. I'd have thought upgrading radiators where necessary, or some basic insulation measures would make more sense, and then use a COP closer to 300%.

You'd also have to consider the need to generate and supply 3x as much leccy.

Also, what about the DHW demand for households that 'enjoy' 12 baths/showers per day, how would they cope?

Is there any field based performance data which shows that a retrofitted ASHP/rads system in a normal home is capable of obtaining a COP of 300%?

I've searched the net a few times for actual performance data and there surprisingly isn't much out there. There's a couple of trials the Energy Savings Trust ran and a couple of University papers and these point to a seasonal COP somewhere between 1.7 - 2.5 for ASHP/Rads systems.

Reed_Richards

If you install a heat pump and want to claim the RHI then you have to install an electricity meter that measures the input power to the heat pump.  You can also monitor the heat output; usually this is an optional extra but in certain circumstances it is obligatory.  So the data for real-world efficiency must be out there.  Give me another six months and I will have a year's worth of data with which to compare my old oil boiler with my heat pump and new radiators.

Heat pumps are so much more efficient if the temperature difference between the heat source and the heat sink is kept to a minimum that the notion that you can get 200% efficiency with old radiators is way more optimistic than the idea that you can achieve 300% with new ones.

shinytop

Baxter100 said:

Martyn1981 said:

Kinda get the feeling that you've rigged that example to get the costs closer. I'd have thought upgrading radiators where necessary, or some basic insulation measures would make more sense, and then use a COP closer to 300%.

You'd also have to consider the need to generate and supply 3x as much leccy.

Also, what about the DHW demand for households that 'enjoy' 12 baths/showers per day, how would they cope?

Is there any field based performance data which shows that a retrofitted ASHP/rads system in a normal home is capable of obtaining a COP of 300%?

I've searched the net a few times for actual performance data and there surprisingly isn't much out there. There's a couple of trials the Energy Savings Trust ran and a couple of University papers and these point to a seasonal COP somewhere between 1.7 - 2.5 for ASHP/Rads systems.

I think ASHPs have moved on a bit since these papers but that's not far off for an ASHP retrofitted without changing rads.  I'm not expecting to achieve a SCOP of 3 even with my completely new system.

Even at 10p/kWh, direct heating just isn't going to be affordable.  And there is a lot of scope for users to generate huge bills; thermostats a couple of degrees too high or Martyn's excessive use of HW described above.  If you double your £500 gas bill through being a bit wasteful that's one thing but a different matter when a £1500 leccy bill turns into 3 grand.  You always need to remember it's the public we're dealing with here.   

Air to water ASHPs are probably the best alternative we have at the moment although they will also have issues in a mass rollout.  They will get cheaper and more mainstream but maybe something better will come along in the meantime.