New gas boiler or electric heat pump?

FlorayG

Octopus can install me a heat pump and all new radiators and a hot water tank and cap off the gas for under £5k.
My gas boiler is over 20 years old and has a minor but irrepairable (parts not available) water leak so needs topping up regularly. My radiators are the single thickness ones so at least as old if not older, so really all needs replacing but will cost more than £5k
Dilemma; will it be cheaper to run all electric? Or replace the gas boiler and radiators?
I also have almost new solar panels and a battery if that will make a difference ( although of course they don't work well in awful grim weather or at all in the dark which is when you need the heating on)
I'd like people's experience please and maybe some links to unbiased information? thank you

tacpot12

I don't have experience of this myself, but I am very interested in people's experience with heat pumps. Others than have solar, battery and heat pumps seem to report the greatest savings, and that the cost is less than using gas. This is based on the use of tarrifs that allow the batteries to be charged overnight using cheap electicity. If you don't use such tarrifs, it's likely that the heat pump will cost around the same as gas if it is installed well, and bit more than gas if the install is not good. 

MattMattMattUK

There are some complications, but based on rough price cap figures gas costs 6.34p per kWh, electricity costs 23.86p per kWh, however you should be able to achieve a COP of 4 on a well utilised heat pump setup, which means you get 4kWh of heat for every kWh of electricity, for a gas boiler you will get around 95% efficiency. so taking that into account your costs would be, per kWh of usable heat:
Heat Pump: 5.97p
Gas: 6.67p

Now you also have to factor in the free electricity you get from your panels, which means for much of the year you will pay nothing at all as you will not need to import energy, or you can export at peak and import at cheap rate (10-5p, sometimes even free and occasionally paid to import overnight). Personally I think that especially as you already have solar and a battery the heat pump is a complete no brainer and it will be cheaper run.

FreeBear

MattMattMattUK said: There are some complications, but based on rough price cap figures gas costs 6.34p per kWh, electricity costs 23.86p per kWh

With a heat pump, it would make sense to switch to a ToU tariff (maybe Octopus Cosy) and get an even bigger saving during the cheap slots. Having batteries would help to reduce running costs during peak periods too.

Reed_Richards

I  replaced an oil boiler with a heat pump four years ago.  I spent an average of £920 per year on oil paying an average of 45p per litre.  Heating oil currently costs about 60p per litre.  So at todays prices that might be £1,230 per year on oil

My heat pump has averaged 5576 kWh per year.  Some of that electricity will have been generated by my solar panels but they do little for me in the winter when the heat pump uses the most electricity.

So for me, there doesn't seem to be much difference in running costs between my old oil boiler and my new heat pump.  I'm sorry that I can't do the comparison with gas that you want but last time I looked, oil was a bit cheaper than gas for running costs.      

littlemoney

I replaced my gas boiler recently with another gas boiler.

I read that a newer, well insulated house is needed for heat pump to be effective plus new radiators and wider bore pipes. I have an old house  so didn't consider and overall cost much higher.

FreeBear

littlemoney said: I read that a newer, well insulated house is needed for heat pump to be effective plus new radiators and wider bore pipes. I have an old house  so didn't consider and overall cost much higher.

A fallacy. A heat pump is just another source of heat. Yes, running costs would be lower in a well insulated home, but so would a gas boiler.

Depending on how old your current CH system is, larger radiators may be needed. But the additional cost would be factored in when they do a survey. If you have a new gas boiler, that too would benefit from larger radiators - You'd be able to run at a lower flow temperature which equates to higher efficiency and reduced corrosion.

Larger bore pipes means you reduce the speed at which water is circulating in the system which means less stress on the pump (as well as a quieter system). Much of it depends on the size of heat pump installed. If you have a 4kW heat pump, a mix of 15mm & 10mm pipes may well cope just fine. An 8kW or 12kW HP would probably need 22/28mm for some of the pipes, but not all.

I have an older house (late 1920s build) with a modern gas boiler - Have been running it with 30-45°C flow temperatures over the last few weeks. Place is heating up and staying reasonably warm, so if I did switch to a heat pump, I would envisage a similar level of comfort at a comparable running cost. Would perhaps want to swap out a couple of radiators, but the pipework won't need any significant changes.

matelodave

£5k for an installed heatpump system compared with probably nearly the same to replace the gas boiler and other system parts sounds like a no brainer. Especially if you've already got solar and batteries as they'll help you shift your consumption to use off-peak tariffs. You'll also have the benefit of dispensing with gas and the associated standing charge.

If you follow most of the threads you'll notice that most of those with a heatpump who put a bit of effort into understanding how it works and tuning it to suit their lifestyle are more than happy. Even more so those who've got batteries and solar.

I've had my heatpump for over 14 years and it just works - probably not quite as efficient as the later units and I probably only get an SCOP of around 3 to 3.5 but 14 years is a long time to have it and still be happy. Even better, my wife is more than happy as well as she is warm and cozy.

We dont feel that our electricity bills at and average of £155 a month are excessive, considering that we are at home all day and it covers all our energy needs for heating, hot water, cooking washing etc.

We dont have the option of mains gas so we'd have to have oil or LPG with the attendant aggro of a big tank and getting it topped up.

At 78 I'm probably a bit too old to get any return on capital from installing solar and batteries so we'll happily soldier on as we are (we should have done it 14 years ago, but we spent the money on a heatpump instead)