Heat pump install vs Gas

A_very_BIG_Goose

We are just coming off a fixed deal, we were paying £460 a year in gas. Now we are faced with some staggering estimates.

If we have to pay more, I would like this to be more of an investment than just dead money on gas.

Is it sensible to consider changing our ancient boiler to an air source heat pump system? 

If anyones done this already, have you got any advice? 

Thanks 
Matt

Mstty

For retrofit (not installed on a new build) come October and the ratio between how much 1kwh gas and 1kwh of electricity costs. It begins to be an even race between gas central heating/hot water and electric air source heat pump heating/hot water.

Gas CH will be cheaper to install. ASHP should last longer and keep its efficiency levels (COP) 

Octopus have entered the ASHP market. 

https://octopus.energy/heat-pump/register/

Finally the ratio gap between gas and electricity is coming down so it is making more sense if this continues.

On the current April 2022 price cap the cost of gas is roughly 7p kWh and elec 28p kWh so you get 4 kWh of gas compared to the price of 1kwh electricity. You should get an average of 3kwh over the year for every 1kwh of electricity you put in with an ASHP. That means gas still wins at the moment (forgetting boiler efficiency which you can calculate yourself)

Come October 2022 best guesses are electrically 45p kWh and gas 14pkwh (roughly 3:1 ratio) hence why I have said for the first time this whole mass install ASHP on paper becomes plausible....just

Alnat1

What sort of property do you have? An ASHP works more economically in a really well insulated (probably more modern) building.

matelodave

A heatpump is going to cost you a lot of money upfront - quite a bit more than a shiny new gas boiler. On top of that it uses full price leccy, so although they are around 300% efficient you will have to compare the price of leccy with the price of gas.

For instance I have got a heatpump and I  presently pay 29p/kwh for my leccy, which is roughly equivalent to 10p/kwh for gas. When leccy goes up to the sort of silly prices they are predicting in October - lets say 60p/kwh  then that would equate to 20pkwh for gas.(I would probably change it to gas if it was available where I live)

My present  total leccy bill is around £2325 per year = 193.75 a month (about £1400 is the heatpump)

I am anticipating it to go up to around £4,000 which is just over £300 a month. Do your sums based on what you pay for gas and then see what it comes out for leccy.

As a rough guess - look at how much gas you use in kwh, divide it by 3 and multiply it by the cost of leccy (use your own figures)

example 12,000kwh of gas at 15p = £1800
= 4,000kwh of leccy at say 50p = £2000

Unless something happens to redress the cost differential between leccy and gas, then gas is still cheaper. Being green or even energy efficient doesn't make it cheaper.

lohr500

Hi matelodave, as someone who has an ASHP, what efficiency factor are you seeing in the real world?

Hi Mstty, with your ASHP setup are you seeing an efficiency factor of 4 on an annual basis? I did some research and lots of googling last year when we were considering an ASHP and most people seemed to think a factor of 3 was bordering on the optimistic side of reality, especially in winter when the heating is needed most.

I'm really interested to know how ASHP installations are performing in the real world.
There seem to be lots of posts from people who are unhappy with the consumption of their ASHP setups and also lots of debate and confusion on the optimal settings for the control systems. 

matelodave

It's hard to tell because all I can go by is the consumption of the unit versus the estimated heating requirements. You may have seen some some posts from @dllive who gets a bit wound up about his COP coz its not easy to measure without specialised testing. - look here - https://forums.moneysavingexpert.com/discussion/6375941/ecodan-are-these-cop-figures-correct/p1

You also have to take in some of the other stuff thats hanging off the heatpump which may or may not be included in the quoted COP but uses energy whilst it's in operation. 

My EPC reckons I need around 15,000kwh (including hot water), my MCS calculates an annual generation of 13741kwh and my best estimate  of consumption is around 4500-5000kwh, so erring on the side of caution 15000/5000 equal around 3 or 13741/5000 = 2.75. My RHI was based on a nominal 2.5.

My gut feel is that its around 3 (but that is an average over the year) obvious it's not as good as that when its everso cold in the winter and probably better than that in the summer, that why SCOP  (Seasonal Coefficient of Performance) is a better measure of overall performance than COP which is defined at specific temperatures

Unfortunately people are confusing cost with efficiency, although a heat pump is around 3 times more efficient, the cost of the fuel is nearly four times that of mains gas so unless you've got it optimised to suit your lifestyleand you've got the controls set properly (and you really understand it) then a lot of people are very disappointed.

All that said, I've had mine for twelve years and I'm very pleased with the way it's performed and even the cost of running it although that was predicated on getting cheap leccy deals which are now very unlikely. I've also put a lot of effort into understanding how it works and tweaking it . Last year my total leccy bill for the whole house was less than £1000, for 7500kwh come October I'm preparing for it to get pretty close to or even exceed £4k

Many people dont' know how to operate it properl or expect to use it like a gas boiler and find that their leccy bills go into orbit.

I personally wouldn't swap out a gas boiler for a heatpump or possible even an existing oil or LPG boiler but they are worth consideration for a completely new installation. In my viwe the only way that they can make them viable for most people is to raise the price of gas or reduce the price of leccy so the running costs are much closer together. Put the carbon and green taxes on gas and take them off electricity, especially if leccy is considered to be the greener fuel.

brewerdave

matelodave said:

Put the carbon and green taxes on gas and take them off electricity, especially if leccy is considered to be the greener fuel.

I'm led to believe that there are 28 million GCH installs in the UK -and the builders on new build sites are adding them daily and they won't go to ASHPs unless there is Govt .compulsion.
 If ASHPs are not installed from day 1 then the capital costs of total replacement systems are eye watering - I was quoted a budget cost of £21k - so what would be the reaction of the masses if they were told replace your GCH or pay £10k pa for heating ???

matelodave

brewerdave said:

matelodave said:

Put the carbon and green taxes on gas and take them off electricity, especially if leccy is considered to be the greener fuel.

I'm led to believe that there are 28 million GCH installs in the UK -and the builders on new build sites are adding them daily and they won't go to ASHPs unless there is Govt .compulsion.
 If ASHPs are not installed from day 1 then the capital costs of total replacement systems are eye watering - I was quoted a budget cost of £21k - so what would be the reaction of the masses if they were told replace your GCH or pay £10k pa for heating ???

I agree but if they are wanting people to change then summat has to give - even just taking the green taxes off would make a pretty significant difference as they are mostly all lumped onto leccy (the best estimate I can get is that it's was around 25% of the cost of leccy a year or so ago. Although thats probably changed now  energy prices have rocketed depending on whether it was a fixed charge or a percentage. The government must be doing pretty well out of just the VAT , even at just 5% now that energy prices have doubled and are due to rise significantly again in October (is that also called a windfall tax)

have a shufti here https://www.altoenergy.co.uk/blog/green-levies-to-be-switched-from-electricity-to-gas I dunno how true it is

Mstty

lohr500 said:

Hi matelodave, as someone who has an ASHP, what efficiency factor are you seeing in the real world?

Hi Mstty, with your ASHP setup are you seeing an efficiency factor of 4 on an annual basis? I did some research and lots of googling last year when we were considering an ASHP and most people seemed to think a factor of 3 was bordering on the optimistic side of reality, especially in winter when the heating is needed most.

I'm really interested to know how ASHP installations are performing in the real world.
There seem to be lots of posts from people who are unhappy with the consumption of their ASHP setups and also lots of debate and confusion on the optimal settings for the control systems. 

Hi Lohr,

This might go on a bit.......lol

Unlike some installs the system we have inherited at 6 years old was built and planned with the house build. So this does seem to make a big difference with the underfloor heating downstairs and not using existing radiators in a retro fit. Sadly as this was put in as a new build install it didn't need an energy monitor on the system to claim the RHI payments. I wish it had one.

We have only been here a year so the is a 4/5 bedroom house and if we have a mild winter like last year we estimate we will use 6150kWh. That entails one hour of hot water heating and the temp set to 20oC. (Down 1oC from last winter to achieve the savings) everything else cooking, refrigeration etc etc.(no other source of power)

Last year we didn't run the weather compensation curve it was me looking at the weather and adjusting the temp flow manually(it's all a big joke now that I found out about the weather compensation curve that does it all for you🤣🤣) I found that info here after last winter lol.

So bit of history and by comparison one of our previous houses was a year old 3 bedroom house with gas CH we used 13000kwh gas and 3600kwh elec (rounded those off). At today's rates 7p gas and 29.234p elec in our region that's £2232 if we still lived there and it was a high B on the EPC.

The house we are in now 4/5 bed designed from new ASHP system is also a high B and with elec at 29.234p. Over the last year(me manually adjusting the flow temp and probably trying to run it more like a gas Ch heating system) was 7205kwh at 29.234p plus standing charges £2276. Basically even running the ASHP badly both houses cost roughly the same (part due to saving £100 on gas standing charges) despite the current one being much larger.

This year we have already made strides to save energy our monthly average at the moment (we work from home full time) is 210 kWh in summer (down about 100kwh a month so far) so our target of 6150kwh is achievable. Total cost (as we fixed at 29.234p kWh £1968 for the year Inc SC

I am not saying we are getting a COP of 4 by any means but in the previous house the boiler probably wasn't 100% efficiently so a mix of that and a cop of more than 3.

I don't think retro fit systems would be able to match what we are seeing but my opinion is every new house should have an ASHP installed, ideally with solar panels and solar hot water heating. That truly would be the trifecta of energy saving and cheap running of a house.

Now looking to October you can see me mentioning April price cap rates of 29p elec 7p gas so roughly electricity is four times more expensive than gas. Come October it is like gas will just be over 3 times more expensive.

So let's take the best guestimates for October 2022 of 45p per kWh Elec and 14p kWh for gas and apply them to our previous 3 bed house. That comes out at £3710. The current 4/5 bed house comes out at £3412 (using the 7205 kWh previous year figures)

I am glad to say we fixed at 29.239p kWh for elec until April 2024 but the above illustrates how the ratio between gas and electricity really is making ASHP a true competitor to Gas central heating.

Reed_Richards

Alnat1 said:

What sort of property do you have? An ASHP works more economically in a really well insulated (probably more modern) building.

This is often stated and it's true but equally it's tosh.  Any boiler or other heat source works more economically in a really well-insulated building.  There is nothing different about an ASHP in this regard; it's just the same as everything else.    

markin

Reed_Richards said:

Alnat1 said:

What sort of property do you have? An ASHP works more economically in a really well insulated (probably more modern) building.

This is often stated and it's true but equally it's tosh.  Any boiler or other heat source works more economically in a really well-insulated building.  There is nothing different about an ASHP in this regard; it's just the same as everything else.    

The must come a point where a low flow temp can't keep up with the heat loss or water usage and the AUX heater is burning away 24/7 in cold weeks trashing the advantage over Gas. Or do we always just put that down to Bad design at install, Or the homeowner that can't work out how to run it efficiently, Or the 3 different service men that can't fix it and simply say 'Its Fine' until the owner or council rip it out and install gas.