Cheapest heating for all-electric 3 bed flat?

Marbles31

Hi there.  We have an all electric flat on a single rate (i.e. not economy 7) tariff, currently heated by a combination of underfloor electric heating (electric mats under fixed floorboards) and some plug in electric oil-heaters.

We end up using heating from November till March, usually for 2-3hours in the morning and 2 hours at night.  We'd love to have it on in the day too but it would be so expensive - back in the 'before-times' it was pricey, but manageable when electricity was around 11p per kilowatt hour with a fix.

Now the prices are insane - we should've done something sooner but here we are.

So...  we're doing some major refurb anyway, should we:

- switch to Economy 7 and get some modern storage heaters installed (e.g. Quantum Dimplex).

- Remain on our single rate tariff and change to a different kind of electric heating

- something else - e.g. is there a form of storage heating which we can use with other time-of-use tariffs such as Octopus agile, which will charge-up when the price of electricity is low.

Or is it the case that, for the vast majority of all-electric flats, the only sensible option is storage heaters which charge up overnight?

Would welcome any advice..!

macman

You've answered your own question. All electric heating is the same efficiency (100%), so the only way to make it cheaper is to buy cheaper kWh units, which means going to E7.
This is not cheap in terms of capital spend, but if you are doing a major refurb, that is the time to do the necessary electrical work, and remetering if not on a smart meter.
Quantums require connection to both the cheap rate and day rate supply. If you want to do it cheaper, you can buy and fit refurb'd NSH's on a single cheap rate supply only, but these will not be as controllable.

Mstty

Do you own the flat or rent?

If you own the flat then an option may be a heat pump aircon unit/heater/dehumidifier.

You can get multi split 2/3 units off the one outside unit.

For every kWh in 3-4kwh output of heat as a guide

Added benefit cheap cooling in the summer as well.

Just a thought and as an example

https://www.appliancesdirect.co.uk/p/argo-2ms9k9k/argo-argo2ms9k9k-air-conditioner

QrizB

Welcome to the forum.

You say you're doing refurbishments so I assume you own your flat, rather than rent? Do you plan to stay there forever, or do you expect to move in 3-5 years?

A former regulr poster @Gerry1 (wonder where he's gone?) maintained a list of options from cheapest to most expensive to run, specifically for questions like yours:

https://forums.moneysavingexpert.com/discussion/comment/78878157/#Comment_78878157

Mains gas (wet radiators)
Mains gas (gas fire)
Oil
Electric Ground Source heat pump (*)
Electric Air Source heat pump (*)
LPG
Electric storage heaters (High Heat Retention, fan assisted) on E7(†)
Electric storage heaters (old style without fan) on E7(†)
Direct electric heating on single rate (e.g. panel heaters / oil filled radiators / fan heaters) (‡)
Electric boiler on single rate (‡)

(*) This may move up or down one row depending on how the price of electricity varies with other fuels. A year ago it might have been cheaper than oil but now it might be more expensive than LPG - that is because the price of electricity is high at the moment.
(†) I've deleted the 'similar tariffs' bit because the legacy tariffs with daytime or evening boosts (THTC and suchlike) are being phased out and now tend to be significantly more expensive than E7.
(‡) The p/kWh cost will be the same, but it's often easier to restrict usage in bedrooms etc by using plug-in devices for spot heating, especially if TRVs are not fitted.

That was in January this year. This coming winter oil and LPG are likely to be cheaper than mains gas but since you're in an all-electric flat we can ignore the non-electric options, leaving us with:

Electric Ground Source heat pump (*)
Electric Air Source heat pump (*)
Electric storage heaters (High Heat Retention, fan assisted) on E7(†)
Electric storage heaters (old style without fan) on E7(†)
Direct electric heating on single rate (e.g. panel heaters / oil filled radiators / fan heaters) (‡)
Electric boiler on single rate (‡)

I don't see a GSHP being an option for a flat but an ASHP might work? Possibly a multi split system like danrd fitted?
https://forums.moneysavingexpert.com/discussion/6269423/7-8k-for-aircon-system#latest

If not, then you're looking at storage heaters.

Reed_Richards

Just to clarify, there are two types of Air Source Heat Pump, air-to-air and air-to-water.

Air-to-air is essentially an air conditioning unit that can be run in reverse for heating.
Air-to-water is essentially a type of boiler that supplies hot (or warm) water to radiators or wet underfloor heating.

Marbles31

Thanks all for the messages -

We'll probably stay here for at least 6 years.  It's a grade 2 listed block of flats so we don't think getting an external box on the walls for an air source heat pump is going to viable, but I guess it's worth asking.

When I've spoken with electricians about air source heat pumps the suggestion is that you need an 'air tight' property for them to work..?

We've looked at something like Tesla's Powerwall - where you can charge up batteries when electricity is cheap and use the power throughout the day, but right now those batteries are SO expensive it doesn't seem to be worth it.  Maybe if we were running a hotel it would be!!

DullGreyGuy

macman said:

You've answered your own question. All electric heating is the same efficiency (100%), so the only way to make it cheaper is to buy cheaper kWh units, which means going to E7.

This to me has always seemed an overly simplistic answer.

At our last gaff we had electric infloor storage heating, worked the same as traditional storage heaters but rather than being bricks in a wall unit it used the concrete of the floor itself as the thermal mass. The issue was it gave out most the heat it'd stored up during the morning/afternoon when the property was empty with us at work (mon-fri) and by the evening much of the heat had dissipated. 

Yes in a sense it was cheapest because its 100% efficient and was charged using the cheaper Economy 7 power but it delivered its benefit at the wrong time.

D924

Mining cryptocurrency is the most effective electric heating if you can't get an ASHP or Economy 7.

Entry cost is virtually zero right now due to extreme unprofitability.

going_cheap

Have you considered IR heating panels? Could be an opton if you are going through a refurb..

macman

DullGreyGuy said:

macman said:

You've answered your own question. All electric heating is the same efficiency (100%), so the only way to make it cheaper is to buy cheaper kWh units, which means going to E7.

This to me has always seemed an overly simplistic answer.

At our last gaff we had electric infloor storage heating, worked the same as traditional storage heaters but rather than being bricks in a wall unit it used the concrete of the floor itself as the thermal mass. The issue was it gave out most the heat it'd stored up during the morning/afternoon when the property was empty with us at work (mon-fri) and by the evening much of the heat had dissipated. 

Yes in a sense it was cheapest because its 100% efficient and was charged using the cheaper Economy 7 power but it delivered its benefit at the wrong time.

The OP asked 'which is cheapest?' Which is based on the heat delivered per kWh of energy purchased. Your argument is about the rate of delivery, not the cost. Yes, different devices will release at different rates, but the efficiency is still 100%.
We are commonly  asked if oil filled rads are more efficient to run than convectors, because 'they retain heat longer'. Which of course they do, but they're slower to release it initially.
NSH's are very suitable for homes that are occupied during the day, but may as you say lose their charge by evening. The solution is to control the output better, which modern ones do.

QrizB

DullGreyGuy said:

At our last gaff we had electric infloor storage heating, worked the same as traditional storage heaters but rather than being bricks in a wall unit it used the concrete of the floor itself as the thermal mass.

As an aside, that's a dreadful design. Storage heaters work by having baffles that minimise allow you to control convective heat loss, so you can have heat when you want it (modern HHR ones are also well insulated so you minimise heat leakage).

Using your floor slab as a storage heater is likely to forfeit any control over when the heat is released.