Heat pump versus economy 7

eddie197

We live in  a residential block of 23 apartments with gas central heating. I am thinking about the possible replacement of the gas combi boiler. We have underfloor heating so a heat pump would probably be  a good option, but outside space for the external equipment could be a problem. The other alternative would be an electric system boiler with a Sunamp Heat Battery using economy 7. We would have to fit timers to the dishwasher and washing machine so that they use economy 7 electricity. Gas is obviously the cheapest heat source, and a heat pump could probably closely match it, but what would be your thoughts on the economy 7 option? We would be relying  on the heat stored in the heat battery (which is like a hot water cylinder, but much smaller) to provide heat for both central heating and hot water during the day.

QrizB

Welcome to the forum.

Switching from gas central heating to a Sunamp heat battery on E7 is likely to double your heating costs in normal times (current tariffs aren't normal).

There are some calculations of typical costs for E7 heating (via storage heaters, but costs with the Sunamp will be similar) here:

 https://forums.moneysavingexpert.com/discussion/comment/78557202/#Comment_78557202

Notice how, in 2021, gas CH was around £500-600 a year and E7 was £800-1200. Last winter E7 was briefly cheaper than gas (due to the government's EPG subsidies) but we're now back to E7 being about £400 a year more expensive.

mmmmikey

Hi @eddie197

I'm a huge fan of various forms of electric heating and can enthuse about it until you have tears in your eyes and are politely willing me to stop. But even given that I think that in your situation you'll find that gas is the least expensive option by some margin.

With a bit of tinkering and numerous caveats it is sometimes possible to get the ongoing cost of electric heating (in it's various forms, including heat pumps) down to much the same level as gas or sometimes even lower. But it seems to me that is very much the exception rather than rule and if you already have a gas connection and boiler then I'd doubt you could save money by changing, especially if you take the cost of the new heaters etc. into consideration.

One possible option to be consider might be to use a smart time of use tariff like Octopus Agile to charge the Sunamp heat battery using energy when it's cheapest. At the moment Octopus Agile is working out way cheaper for me than E7. But there's a huge caveat - the rate is not guaranteed so you could end up paying more (or less or about the same ) over the winter months when you need it the most. It really is impossible to predict as energy prices have been extremely volatile both from day to day and during the day. But possibly something to think about if you want to do something adventurous.

Hope this helps in some way, let us know what you decide and/or come back with further questions.

Gerry1

eddie197 said:

We would have to fit timers to the dishwasher and washing machine so that they use economy 7 electricity.

Spin drying after midnight will make you very popular with the neighbours !  Also discouraged by the fire brigade.
You also need to think how a heat pump would be viewed by potential purchasers of the property.  GCH will be well received but a heat pump may be viewed with suspicion.

matelodave

there's also a better than even chance that swapping a gas boiler for a heatpump could make your EPC rating worse.

eddie197

Thanks for your comments. Yes, spin drying at night would be a problem, although the flats are pretty sound proof. The comparison of energy costs was interesting and I need to do the same for my own costs. I certainly intend to hang on to my gas boiler for as long as possible, but I suspect I will have to go down the E7 route eventually.

Scot_39

matelodave said:

there's also a better than even chance that swapping a gas boiler for a heatpump could make your EPC rating worse.

1) The OP lives in a flat - heat pumps may not be an option.

2) Not if Greens have their way - as per Scottish Proposals.

https://forums.moneysavingexpert.com/discussion/6461908/snp-plan-to-outlaw-sale-of-houses-with-gas-boilers

Outlaw may be a bit strong - but it certainly has opposition press pretty furious up their.