UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

Scwgrahame

Well know I don't want to pay 16k. I would prefer it for free but if not I want to pay as close as I can to the price I would pay for a gas option.  The 16k was all in, radiators yes.
Everything I have read says its cheaper to run. 

Cardew

Most people with gas CH would consider it a downgrade to have an ASHP.

If you were lucky enough to get an ASHP with a system COP of 3.0(and there is no guarantee you would get COP = 3.0), and with Electricity at, say, 14p/kWh you would have a cost of  4.67p/kWh; that is almost double the cheapest gas available.

Where did you read an ASHP 'can save money'?

Why would replacing an existing gas CH system for a 3 bed house cost 'in excess of £5k' - even British Gas shouldn't charge that much. £3k would be nearer the mark.

matelodave

You probably wont save on running costs if you swap from mains gas to an ASHP and even with the RHI I'd doubt that it would pay the difference in cost between it and a gas boiler. You also have to run an ASHP in a completely different way to a gas boiler so it may not actually suit your lifestyle.

To get maximum efficiency they have to run at low flow temperatures which means radiators that are probably double the size of your existing ones and you really have to heat the place virtually continuously because of the slow response.Many people find that the really slow heating response just doesn't suit them so they crank the unit up and it then costs them a lot more to operate.

I have had an ASHP for over ten years and I'm very happy with it. It suits our lifestyle as we are at home all day so the heating runs all the time but if we turn it down too far or off it can take hours or even days to get the house back up to temperature.

I presently pay 12.25p/kwh for leccy and, assuming that my average COP over the year is around 2.5-3,  a kwh of heat costs around 4.5p whereas most people can get mains gas for less than 3p/kwh so it's difficult to see how they are cheaper to run than mains gas.
I guess they are cheaper to run than LPG and probably about on a par with oil (and they have the advantage of not needing a big tank in the garden So do some very careful sums and think about how you'll use it before making the jump.

If mains gas became available to my hamlet  tomorrow I'd be more than tempted to replace it with a gas boiler.

danrv

matelodave said:

if we turn it down too far or off it can take hours or even days to get the house back up to temperature.

Wow. 
My three bed semi detached all electric property would suit wet central heating. I think air con is the best bet for me though. Cheaper install plus I’m used to the instant heat of my current warm air system.

richardc1983

Scwgrahame said:

Well know I don't want to pay 16k. I would prefer it for free but if not I want to pay as close as I can to the price I would pay for a gas option.  The 16k was all in, radiators yes.
Everything I have read says its cheaper to run. 

Read the very first post.... 

matelodave

danrv said:

matelodave said:

if we turn it down too far or off it can take hours or even days to get the house back up to temperature.

Wow. 
My three bed semi detached all electric property would suit wet central heating. I think air con is the best bet for me though. Cheaper install plus I’m used to the instant heat of my current warm air system.

As I said, the slow response doesn't bother us as we are at home all day but it may not suit households where you only want a quick boost in the morning before you go to work and then again for a few hours in the evening. Ours is slowed down a bit more by having underfloor heating which tends to work more like storage heating than radiators.
Normal radiators are designed to run at a flow temp of around 70C (a temp difference (deltaT) of around 50C in a room at 20C) whereas a heat pump is most efficient at about 35-40C which is only a tempt difference of 15-20C so the radiator sizes need to be significantly increased to compensate. Have a look here - https://www.buildingservicesindex.co.uk/entry/136540/AEL-Heating-Solutions-Ltd/How-to-calculate-the-delta-T-for-a-radiator/

You can run a heat pump at higher temperatures but the COP efficiency decreases and the running costs increase significantly. Most heatpumps are limited to 55 degrees but that will use about 50% more electricity than running it at 35C. Trying to get temperatures above 55 degrees either for heating flow or hot water requires the use of a immersion heater which has a COP of 1

Hermann

Scwgrahame said:

I have a mains gas central heating system at the moment. To replace that will most likely cost in excess of 5k so was looking at alternatives and the ASHP caught my eye. I read that it can save money and of course there is a green aspect to it also.
Like any big purchases though I need to shop around so was just looking for anyone on here who could recommend. 

I'm just going to be blunt.
You've been taken in by the marketing men trying to con you out of your money.

An ASHP is not going to be cheaper to run than mains gas.

£5k sounds like a very over the top cost for replacing an existing gas boiler, unless there is something particularly unusual about your set up.

Why are you even considering a replacement gas boiler? Unless it has failed beyond economic repair there is no point in replacing it. A new boiler may quote much higher efficiency figures but in reality whilst they will be slightly cheaper running costs the savings won't cover the capital cost to change the boiler. The new boiler will have failed or need major investment in repairs long before it's paid for itself.

The time consider a new gas boiler will be when the old one fails. 

Scwgrahame

Hermann said:

Scwgrahame said:

I have a mains gas central heating system at the moment. To replace that will most likely cost in excess of 5k so was looking at alternatives and the ASHP caught my eye. I read that it can save money and of course there is a green aspect to it also.
Like any big purchases though I need to shop around so was just looking for anyone on here who could recommend. 

I'm just going to be blunt.
You've been taken in by the marketing men trying to con you out of your money.

An ASHP is not going to be cheaper to run than mains gas.

£5k sounds like a very over the top cost for replacing an existing gas boiler, unless there is something particularly unusual about your set up.

Why are you even considering a replacement gas boiler? Unless it has failed beyond economic repair there is no point in replacing it. A new boiler may quote much higher efficiency figures but in reality whilst they will be slightly cheaper running costs the savings won't cover the capital cost to change the boiler. The new boiler will have failed or need major investment in repairs long before it's paid for itself.

The time consider a new gas boiler will be when the old one fails. 

Thanks for replies. Yes possibly been taken in but always interesting to explore new tech. I actually understand the workings of an ASHP better than gas as my place of work uses similar set up but to cool servers!  I currently have a back boiler so it's a pain as I am stuck with the fire, a water tank in loft and a load of other bits in a cupboard I don't want. I am looking to extend house next year so in my head made sense to upgrade heating. 

matelodave

It's probably not unreasonable to upgrade the heating system if its part of a greater plan but it's not something I'd contemplate unless I'd got all my plans in place and I certainly wouldn't consider an ASHP if I had mains gas available.

GGSid

Scwgrahame said:

Hermann said:

Scwgrahame said:

I have a mains gas central heating system at the moment. To replace that will most likely cost in excess of 5k so was looking at alternatives and the ASHP caught my eye. I read that it can save money and of course there is a green aspect to it also.
Like any big purchases though I need to shop around so was just looking for anyone on here who could recommend. 

I'm just going to be blunt.
You've been taken in by the marketing men trying to con you out of your money.

An ASHP is not going to be cheaper to run than mains gas.

£5k sounds like a very over the top cost for replacing an existing gas boiler, unless there is something particularly unusual about your set up.

Why are you even considering a replacement gas boiler? Unless it has failed beyond economic repair there is no point in replacing it. A new boiler may quote much higher efficiency figures but in reality whilst they will be slightly cheaper running costs the savings won't cover the capital cost to change the boiler. The new boiler will have failed or need major investment in repairs long before it's paid for itself.

The time consider a new gas boiler will be when the old one fails. 

Thanks for replies. Yes possibly been taken in but always interesting to explore new tech. I actually understand the workings of an ASHP better than gas as my place of work uses similar set up but to cool servers!  I currently have a back boiler so it's a pain as I am stuck with the fire, a water tank in loft and a load of other bits in a cupboard I don't want. I am looking to extend house next year so in my head made sense to upgrade heating. 

A Heat pump is more efficient in terms of energy use but electricity is a relatively expensive type of energy per kWh.  
I was quoted ~£11K by a couple of firms for ASHP install. Then + cost to replace radiators worked out to another £2K+ on top. I was eligible for close to the maximum amount of RHI which would have repaid a significant chunk of the install cost but still leaves a significant cost. Running costs even at a claimed COP of >4 was more expensive than oil. 
This was not a good way to save money, but it would save a big chunk of CO2 emissions which is a worthwhile aim to have.

If you are building an extension and you have a back boiler then you have a lot of cost baked in already. Might be worth considering things like underfloor heating and radiators capable of running at low temperature in future. We cant continue to set fire to dinosaur juice every time we gett cold, so at some stage we will all need to find a better solution. Equally you should consider insulation as a very high priority. If you get high standard of insulation across old and new then you minimise the future costs of whatever you do install. If you get to passive house standard you dont need to put so much heat in (though you may struggle to get rid of excess heat in summer). 
If you are open to other technologies Air 2 Air heat pumps (aircon) are surprisingly efficient and install costs are not especially high. There is no govmt support for this as they (not so unreasonably) think people with aircon will use more energy in summer to cool their houses so environmentally undesirable. that said if we (as predicted) regularly see temperatures of 30-35C in 10 years aircon will likely become popular. You would however have a major gap to fill with domestic hot water heating if you go that way. I was surprised how much energy was required for heating DHW, it is a much bigger consideration than I initially thought it would be.