Heat pump quote

BuildTheWall

Hi, we have received a heat pump quote from Octopus and wanted to get the thoughts of forum members if its worth the switch. 
Using gas boiler currently, with heating turned on only if necessary, consuming roughly 4200 kWh a year as ours is a mid terrace property. The quote is 2.9k for eco and 2.5k for the turbo version. 
What is surprising is that the quote predicted an electricity cost of £700 per year, much higher than what the roughly £400 we pay for gas (though it may not be like for like as heat pump would keep the house warm consistently while we switch off gas heating as quickly as possible).
That £400 paid currently includes the standing charge. Need to find out which tariff they have assumed. We are getting an EV and thinking of getting solar + battery, therefore the electricity cost can be as low as 7p. 
It looks like the savings might not be worth the investment? We also have the issue of replacing the gas hob as otherwise we need to keep paying standing charge.

matelodave

If you think you are only using 4200kwh with your gas boiler (does that include hot water as well) then a simple rough and ready guess would be that a heatpump with an SCOP of say 3 would generate 4200kwh of heat using around 1400kwh of electricity.

Dunno what you pay for leccy but at 25p/kwh, 1400kwh would cost £350.  However if you decided to keep the house warm for longer and be more comfortable then maybe you'd use more than 4200kwh, but you would have the advantage of getting rid of the gas standing charge.

You really need to understand what the quotation assumptions are in terms of heat loss, energy generated, energy consumed, temperatures and cost of input energy. Likewise you need to understand that there are specific requirements and rules for heat pump installations based on MCS specifications for heatpump installations which may not correspond with the way your existing gas system was installed or is being used. The design is based on the house requirements rather than the way you would actually use it or are using your existing system

If you did decide to add solar and batteries and get an EV then the whole calculation changes  because the integration of all these systems will give greater benefits and cost savings than just looking at one in isolation.

You would be generating your own electricity and either using or storing it, possibly selling some back and sometimes storing cheap leccy overnight for use during the days when your solar  doesn't generate enough.

Obviously you cant ignore the not inconsiderable upfront investment costs especially if you have to borrow money to get it all up and running so you really need to do your sums

stripling

@BuildTheWall
It looks like the savings might not be worth the investment? We also have the issue of replacing the gas hob as otherwise we need to keep paying standing charge.

Did you have these thoughts when you bought a gas boiler?
It's interesting that everything these days is an 'investment' that needs a 'return'. Rather than say a product that should be reliable, last years and be efficient... Funny how the language and way of thinking has shifted. 

It seems you need to ask yourself what level of comfort you want and why you want to change your heating system. Do you wish to bring down your carbon footprint?  Is your boiler on the
way out? The trio of heat pump, battery and solar is great if you can afford it.  Even better with an EV. To me, that's a good move towards future-proofing.

I have a heat pump but no batteries or solar and it is still a bit cheaper to run than my old gas condensing boiler (which died).  I boosted my loft insulation which made a small impact too. 

As for the hob, electric is better for your health. Gas hobs put horrible pollutants into your home  which have a really bad impact on your heart and lungs, including nitrogen dioxide, carbon monoxide and benzene. This happens even when they are turned off.  A hob change is not major but getting rid of gas completely feels pretty good. 

FreeBear

stripling said: As for the hob, electric is better for your health. Gas hobs put horrible pollutants into your home  which have a really bad impact on your heart and lungs, including nitrogen dioxide, carbon monoxide and benzene. This happens even when they are turned off.  A hob change is not major but getting rid of gas completely feels pretty good. 

Have had an induction hob myself for several years now. Just like cooking on gas, but with the added advantage of much easier to keep clean. Unlike gas, the heat goes in to the pan, and you don't lose any up the sides, so it is more efficient (85% compared to 40% from gas). On the downside, you do need a dedicated feed from the consumer unit which might not be there with just a gas hob.

Reed_Richards

I agree completely with the comments by @matelodave but here is an alternative calculation/estimation.

Take the tariff that you pay per kWh for electricity and divide that by 3 then divide that number by the tariff you pay per kWh for gas.  If the number is less than 1 then it should be cheaper to run a heat pump.  If the number is greater than 1 then gas may be cheaper to run.

I suspect that you will find the number you get is close to one, which means there would not be a big difference in running costs.  And the calculation assumes that you want the same amount of heat from your heat pump as from your gas boiler, that your gas boiler is 100% efficient (likely to be nearer 90%) and that your heat pump gives you an average 3 kWh of heat for every 1 kWh of electricity (which you should comfortably achieve, but more easily if you opt for "Eco").

By the way, I am on an EV tariff which means that, currently, the average cost of my electricity is 19.05 p per kWh.  And I heat my hot water during the cheap rate hours which means that the cost of my hot water is much cheaper than if I had gas.    

The_Green_Hornet

FreeBear said:

stripling said: As for the hob, electric is better for your health. Gas hobs put horrible pollutants into your home  which have a really bad impact on your heart and lungs, including nitrogen dioxide, carbon monoxide and benzene. This happens even when they are turned off.  A hob change is not major but getting rid of gas completely feels pretty good. 

Have had an induction hob myself for several years now. Just like cooking on gas, but with the added advantage of much easier to keep clean. Unlike gas, the heat goes in to the pan, and you don't lose any up the sides, so it is more efficient (85% compared to 40% from gas). On the downside, you do need a dedicated feed from the consumer unit which might not be there with just a gas hob.

You can buy a 13 amp induction hob which can be plugged into a standard socket but it will limit the overall power to the heating zones.

13 Amp Induction Hobs Deals at Appliances Direct

Are 13 Amp Induction Hobs Any Good? - Pros, Cons & Advice

Alnat1

As the OP mentions a gas hob, as if it is separate to their (non gas?) oven, I think they will have the necessary electricity feed coming into the kitchen.

FreeBear

Alnat1 said:

As the OP mentions a gas hob, as if it is separate to their (non gas?) oven, I think they will have the necessary electricity feed coming into the kitchen.

Quite a few ovens can be run off a 13A socket.

Strummer22

FreeBear said:

Alnat1 said:

As the OP mentions a gas hob, as if it is separate to their (non gas?) oven, I think they will have the necessary electricity feed coming into the kitchen.

Quite a few ovens can be run off a 13A socket.

But not at the same time, though ;-)

BuildTheWall

Thanks everyone for the comments, am sorry I didnt post the data regarding assumptions. Now i have them, here they are: Estimated heat loss - 5400watts, energy for space heating - 8400 kwh, for hot water - 3150kwh, design flow temp - 50C, SCoP heating - 3.21, SCoP hot water - 2.77, estimated energy consumption for heat pump - 3750 kwh.
Its strange that they estimate about 11500kwh used by gas, but i get just 4200kwh working backward based on my bills. I turn on heating only absolutely necessary, which would be the biggest factor for the difference, but I assume they have estimated based on worst case basis and also that heat pump works continously?
While it looks increasingly a poor return financially, the comfort and convenience of having constant warm temperature is making it attractive as I can avoid partner getting annoyed for not turning on heating often. Also, as many have said above, it makes the case stronger for solar+battery (or just the battery as a minimum). I'll be moving to octopus intelligent go in 2 months as my variable fix ends and I get an EV at the same time, which is also when i plan to take a decision on solar. 

BuildTheWall

stripling said:

@BuildTheWall
It looks like the savings might not be worth the investment? We also have the issue of replacing the gas hob as otherwise we need to keep paying standing charge.

Did you have these thoughts when you bought a gas boiler?

Well, the gas boiler came with the house when we bought it. Its 10 years old now, same as the house as its a new build. Probably good for another 5-10 years? 

stripling said:

@BuildTheWall
It looks like the savings might not be worth the investment? We also have the issue of replacing the gas hob as otherwise we need to keep paying standing charge.

As for the hob, electric is better for your health. Gas hobs put horrible pollutants into your home  which have a really bad impact on your heart and lungs, including nitrogen dioxide, carbon monoxide and benzene. This happens even when they are turned off.  A hob change is not major but getting rid of gas completely feels pretty good. 

Thanks, never considered that before. Makes the case for removing gas connection even stronger. Why not get it done if Octopus offers to do it for free.

stripling said: As for the hob, electric is better for your health. Gas hobs put horrible pollutants into your home  which have a really bad impact on your heart and lungs, including nitrogen dioxide, carbon monoxide and benzene. This happens even when they are turned off.  A hob change is not major but getting rid of gas completely feels pretty good. 

 On the downside, you do need a dedicated feed from the consumer unit which might not be there with just a gas hob.

How do we find if we have a dedicated feed? This is my worry. Ordering an electric hob and the installer finds something missing and that requires further spending.