Electric heater or heat pump for a 5 bed house? To replace a gas boiler

[ParentOfOne]

We have a 5-bed mid-terrace house, with 2 bathrooms and 13 radiators.
Heating is with a gas boiler in the loft, and a hot water tank under the eaves.

We are trying to look into greener alternatives to heat the house - can any one talk to us about heat pumps, electric boilers, etc?

On electric boilers, I can't quite understand if an electric boiler would be adequate for the size of the house - I can find lots of combi electric boilers, but can an electric boiler work with a water tank and with this many radiators?

As for heat pumps, how many types are there? I understand the external unit falls under permitted development, but only if certain boxes are ticked (small unit, no aircon www.legislation.gov.uk/uksi/2015/596/schedule/2/part/14/crossheading/class-g-installation-or-alteration-etc-of-air-source-heat-pumps-on-domestic-premises ).

Also, are there heat pumps which replace the boiler and heat pumps which only heat one or two rooms but don't provide hot water?

Our electricity provider claims it sources 100% renewable energy (let's hope it's true).

I have an electric boiler and my installer told me there was a max number of radiators it would do and left my hot water on the immersion heater. 3 bed house.

This may have had something to do with my weird plumbing (all my pipes are the wrong size as well) but only an installer can tell you if electric will work.

Personally I love my electric boiler as it was much cheaper to install, doesn't make any noise, and although it is more expensive on electricity than some of the other options it was sooooo much cheaper that it will be 20+ years before we are paying the extra costs.

Do you have a combi boiler (ie without a tank) or one with a tank?

What do you mean hot water was left with immersion heater. Immersion = gas? Do you have an electric and a gas boiler? Or two types of electric boilers, one for the hot water, the other for the radiators?

We looked into an electric system to replace our current gas (combi boiler) fuelled radiators. We have 18 radiators. It may become cheaper as renewables become the dominant source of electricity, but at the moment it would be prohibitively expensive to run, and tbh, we couldn't afford it .

We also looked into this when our oil boilers needed replacing 18 months ago. We were keen to replace it with an electric heat pump system.

We have a similar size house and number of rads and the advice we were given at the time was that the heat pumps might not be able to heat the size of house or provide sufficient quantities of properly hot water. So reluctantly we installed a new oil boiler.

Like the PP, hoping that in a few years the technology will have moved in and we can switch over to an electric heat pump system.

Radiators run on the electric boiler, hot water is in a tank with an old school electric immersion heater comes on twice a day. Once the hot water is gone, it's gone!

@reprehensibleme thinking about it I only have 7 radiators. There clearly is a limit to what an electric boiler can do before your electric bills run out of control.

Beware, I have been investigating heat pumps lately and what I found wasn't good. There is an excellent thread on Gransnet about this. Apparently, the bit that goes on the outside is so noisy, that folk have complained to neighbours about the noise. Also, they do not heat the house as well as gas boilers do. Someone reckoned your radiators can be turned up full and the heat still isn't enough. Find the thread on Gransnet as it had posts from people who actually had them installed. Personally, I will be sticking with my gas boiler. I have a health condition and need my home heated properly.

I looked (briefly - it was an emergency, January with no bloody heating) into air source heat pumps and as @hannahcolobus says, decided against as I have a poorly insulated old house.

The internet is awash with stories of unhappy owners of pumps who live in draughty houses who now can't get them warm. They are best for well insulated homes.

On noise: are you sure it wasn't neighbours from hell complaining?
I have seen some specs for external units producing ca. 50 dBs of noise 1 metre away; the farther you go, the more the noise reduces. Plus in the winter people tend to keep their windows closed most of the day.

Maybe not for the whole house, but at least for the kitchen and the living room, which is where we spend most of the day, I wouldn't mind an airocn which can also work as a heat pump. I have seen houses with this setup where it works really well. Unfortunately, that requires planning permission, which I am unlikely to get because of the noise (even if I don't think 50 dB is loud at all).

On how well they heat the house: do you have the details? Didn't they simply install a system which wasn't powerful enough for the rooms in question?

You could look into evacuated solar tubes for water heating if you want to reduce your consumption. My parents got some about 20 years ago and they have only recently needed replaced.

Air source heat pumps do work. But it depends on how well a house is insulated . Older properties that have them retrofitted will struggle to heat the sufficiently, and the cost of running one will be more than gas.

There are lots of forums with information about them and if your thinking of going down that route do your homework before you choose.

They noise they create when running apparently is more noticeable to some people more than others ( depends on your noise tolerance). But like anything with moving parts the older it gets the more noise it will create.

I looked in to just running to house on just electricity when we moved here as it needed a complete refurb, but the cost of running purely on electric was far too expensive than gas.

Heat pumps will be the future ( or hydrogen). But the cost of installation and the price of electricity need to come down to make it affordable for the average person.

Some good information on the piston heads forum about heat pumps if your interested.

I understand I can't get an heat pump because of noise and planning permission.
So the only option is probably an electric boiler, assuming it can work with a house this size.

Heat pumps heat the house at a slower rate that gas boilers do. This means they have to be left on more to keep the house up to temperature. So bigger radiators and underfloor heating are best for this.
But if the house is losing the heat faster than the heat pump can warm the house due to poor design/ age/ insulation then it’s not going to keep the house warm enough. Without having it ruining more and costing more to run

The key to heat pumps is having a super installed house and I don’t mean double glazing and loft insulation, they need to be built using insulated building materials.

Electric will work , it will just cost a lot more than gas , or oil.

My niece has an electric boiler in her house. She finds it expensive and the repair bill large when it goes wrong. She has no option for gas either.

Hmm. 100% renewable energy? According to the National Grid, only around 50% of its power is from renewable sources, so I don't believe that 100%. Also, it's the national grid...at any one time it is drawing power from a multitude of sources. You can't specify that you only want your electricity to come from wind turbines, for example.
You mention 50 decibels of noise for a heat pump. Actually, that's quite loud. I would not be happy if my neighbour was making that noise with heating.
One other thing. Retrofitted heat pump systems (as opposed to new houses designed and insulated for their use) heat water to a much lower temperature, which can cause a problem with legionella bacteria forming. That would be enough to put me off. If heat pumps are so marvellous, why are thousands of new homes being built with gas boilers? Modern gas boilers are clean and efficient and not expensive to run. I wouldn't touch an electric boiler with a bargepole tbh.

@ParentOfOne

I understand I can't get an heat pump because of noise and planning permission. So the only option is probably an electric boiler, assuming it can work with a house this size.

If you're determined to have high costs, and therefore won't have a gas boiler.

50 decibels is not that loud, I disagree.

Most of continental Europe does not have this rule yet they somehow managed to survive without hearing loss...

50 dB is roughly a quiet conversation at home: www.iacacoustics.com/blog-full/comparative-examples-of-noise-levels.html

At 6 metres it becomes 44 dB. At 10 metres, 40 dB
www.omnicalculator.com/physics/distance-attenuation
Even less if there are walls etc in between.

Think this is too loud? Fine, then that's why even people like me, who'd be willing to do something concrete for the environment (not dancing to broccolis, Extinction-Rebellion style) end up polluting more than they otherwise could to heat their homes.

As for 100% renewable energy, yes, I am sceptical, too. It would be interesting to understand more.

@PigletJohn, I would like to understand the environmental / cost implications.

I already know that gas boilers are cheaper to run.

I'd like to understand if an electric boiler can heat our house, and how much more expensive / greener it would be.

If it costs 4 times as much and would struggle to cope, of course not. If it can cope and would cost, I don't know, 20% more but be much greener, we can think about it.

At least trying to look into this is, methinks, more useful than all the ill-thought protests and initiatives we have seen lately, from low-traffic neighbourhoods which displace traffic from the terraced houses to the flats above a shops, to the clowns blocking the city and dancing to broccolis, etc.

"I'd like to understand if an electric boiler can heat our house, and how much more expensive / greener it would be."

More than five and a half times as much.

1kW of energy from gas costs me 3.06p

1kW of energy from electricity costs me 17.13p

Your tariff may differ but is probably something similar.

kWh, I meant, obv.

I wouldn't give up without doing a bit more reading up OP. A mid-terrace is naturally quite an efficient shaped building (two walls 100% insulated by the neighbours!) though of coures it also depends on what your windows and roof are like. But I expect you have done the basics of insulating the loft to 300 or 400mm etc.

We are planning to get a heat pump as the gas boiler is on its last legs, and so we did a 'trial'. (We basically turned the boiler down to run the radiators at about 40 or so degrees (which is what a heat pump does) and let it run to see if we were still warm - and we were. (we did this in winter obviously!!) If you have enough radiators then 40 or 45 degrees will heat your house, you just need to run the heating for more hours to make up for the lower temperature. You are putting in exactly the same amount of heat, just more slowly. And using less energy to make the same heat because heat pumps are so efficient.

You can also get more heat into the house by swapping some radiators in the biggest spaces for extra-big radiators (even triple ones) - these are not hugely expensive. Or adding one or two small ones eg in a hallway or landing. Underfloor heating is ideal, and wonderful to have, but obviously that could end up costing more than the heat pump!

But basically you need someopne who knows what they are doing to come and do some calculations. They will work out what size heat pump you need (the more efficiency improvements you've been able to do, the smaller the heat pump can be) and how much radiator area you need to get the heat into your house (you might have enough, with 13, but an expert will measure them for you and work out if they are right for your rooms) and also if your hot water tank is in a suitable location and well-enough insulated. (you might need to get a new, bigger coil, on the same basis that you might need bigger radiators)

They should also tell you what subsidy you can claim. There is a good pay-back on heat pumps at the moment, but in March it swaps over to a cash-up-front arrangement, which might not be quite so generous, though it is is still pretty good

Definitely google and read around on this. And if you decide to go for it, be fussy about your installer, as some of the bad experiences come from bad installations (pump too small or too big, radiators or timers set up wrong., etc) , rather than heat pumps being inherently unsuitable.

So, basically, switching to a 'green' energy supplier, one which uses renewable energy and ideally 'green' gas, might be better for the environment and my wallet... Something like Ecotricity or Green Energy UK?

I second @candycane222 's comment - everything they've said is spot on. From March 2022, there will be up to a £7000 up-front cash payment available to help people install heat pumps, so it's definitely worth hanging on for that if you can.

With regards to your question about the kitchen, there's two type of air source heat pumps - air-to-air and air-to-water. Given that you have a water-based heating system now, with hot water generated by your gas boiler and fed through radiators, you'd be looking at an air-to-water type heat pump. However, the air-to-air ones work through air heating instead, and can be used for cooling in summer if that's something you'd also be interested in. They're also generally a little cheaper to install.

Air source heat pumps ARE permitted development in a domestic setting in the UK, depending on the size of them, but to heat a 5 bed house, it might be that you need two outdoor units, which then would require planning permission.

Look for an MCS-accredited installer if you're thinking about it (you can find them here). Always worth asking them to give you a quote just so you have an idea of cost before you make any final decisions.

@lils11, I understand air source heat pumps are permitted development only if they meet all the criteria listed at
www.legislation.gov.uk/uksi/2015/596/schedule/2/part/14/crossheading/class-g-installation-or-alteration-etc-of-air-source-heat-pumps-on-domestic-premises

ie they must heat only (no air conditioning)
and the volume of the external unit < 0.6 cubic metres

I must look into it, but, even if I find a system which heats only, no aircon, it may well need a bigger external unit