Still trying to make the numbers work for a heat pump

Martyn1981

That is interesting, I had the exact opposite impression that a heat meter was part of the RHI requirements and it was this that was used for subsidy claims, and capped at 20,000kWh pa for properties whose EPC is greater (like my sister's).

Be interesting to know but whether it's metered or not, wouldn't it still be capped at your EPC even if you used more?

michaels

Martyn1981 said:

That is interesting, I had the exact opposite impression that a heat meter was part of the RHI requirements and it was this that was used for subsidy claims, and capped at 20,000kWh pa for properties whose EPC is greater (like my sister's).

Be interesting to know but whether it's metered or not, wouldn't it still be capped at your EPC even if you used more?

https://energysavingtrust.org.uk/renewable-energy/installation/renewable-heat-incentive

Ofgem will make payments on a quarterly basis for seven years. Normally the heat required to heat the property is deemed (estimated) and payments based on this amount.

Metering There are two types of metering that you may need on the Domestic RHI scheme: metering for payment and metering for performance. Metering for payment Most domestic systems payments will be based on an estimated heat output (’deeming’) but in some cases, Ofgem may base payments from metered output. The most common scenarios for this requirement are: You have ‘back-up’ heating or a heating system designed to only partially heat the property The property is occupied for less than half the year There are other scenarios where metering for payment is a requirement though, and we suggest reviewing Ofgem’s Essential Guide to Metering for a full list. Metering for performance Changes to the domestic RHI mean that heat pumps registering for the scheme from 22 May 2018 must meter for performance. If you’re only required to have metering for performance, you will continue you receive payments based on ‘deemed’ heat demand, as determined by your Energy Performance Certificate (EPC) or heat demand limit.

So looks like metering for performance is reequired but by default payment is deemed based on the EPC.

Martyn1981

michaels said:

Martyn1981 said:

That is interesting, I had the exact opposite impression that a heat meter was part of the RHI requirements and it was this that was used for subsidy claims, and capped at 20,000kWh pa for properties whose EPC is greater (like my sister's).

Be interesting to know but whether it's metered or not, wouldn't it still be capped at your EPC even if you used more?

https://energysavingtrust.org.uk/renewable-energy/installation/renewable-heat-incentive

Ofgem will make payments on a quarterly basis for seven years. Normally the heat required to heat the property is deemed (estimated) and payments based on this amount.

Metering There are two types of metering that you may need on the Domestic RHI scheme: metering for payment and metering for performance. Metering for payment Most domestic systems payments will be based on an estimated heat output (’deeming’) but in some cases, Ofgem may base payments from metered output. The most common scenarios for this requirement are: You have ‘back-up’ heating or a heating system designed to only partially heat the property The property is occupied for less than half the year There are other scenarios where metering for payment is a requirement though, and we suggest reviewing Ofgem’s Essential Guide to Metering for a full list. Metering for performance Changes to the domestic RHI mean that heat pumps registering for the scheme from 22 May 2018 must meter for performance. If you’re only required to have metering for performance, you will continue you receive payments based on ‘deemed’ heat demand, as determined by your Energy Performance Certificate (EPC) or heat demand limit.

So looks like metering for performance is reequired but by default payment is deemed based on the EPC.

Cheers, so the EPC cap would still apply to you either way then, so not a loophole?

michaels

Martyn1981 said:

michaels said:

Martyn1981 said:

That is interesting, I had the exact opposite impression that a heat meter was part of the RHI requirements and it was this that was used for subsidy claims, and capped at 20,000kWh pa for properties whose EPC is greater (like my sister's).

Be interesting to know but whether it's metered or not, wouldn't it still be capped at your EPC even if you used more?

https://energysavingtrust.org.uk/renewable-energy/installation/renewable-heat-incentive

Ofgem will make payments on a quarterly basis for seven years. Normally the heat required to heat the property is deemed (estimated) and payments based on this amount.

Metering There are two types of metering that you may need on the Domestic RHI scheme: metering for payment and metering for performance. Metering for payment Most domestic systems payments will be based on an estimated heat output (’deeming’) but in some cases, Ofgem may base payments from metered output. The most common scenarios for this requirement are: You have ‘back-up’ heating or a heating system designed to only partially heat the property The property is occupied for less than half the year There are other scenarios where metering for payment is a requirement though, and we suggest reviewing Ofgem’s Essential Guide to Metering for a full list. Metering for performance Changes to the domestic RHI mean that heat pumps registering for the scheme from 22 May 2018 must meter for performance. If you’re only required to have metering for performance, you will continue you receive payments based on ‘deemed’ heat demand, as determined by your Energy Performance Certificate (EPC) or heat demand limit.

So looks like metering for performance is reequired but by default payment is deemed based on the EPC.

Cheers, so the EPC cap would still apply to you either way then, so not a loophole?

Based on this link, looks like you are right, shame the MCS guy I was talking to yesterday wasn't aware of this.
https://www.ofgem.gov.uk/system/files/docs/2018/07/essentialguidetometering_july_2018.pdf

Reed_Richards

My understanding is much the same.  You are obliged to have a meter to get the RHI payments but this justified on the basis that you should be able to see the performance.  Payments are on deemed usage from the EPC unless you have another major heat source such as a boiler in addition to the heat pump.

shinytop

I decided to revive @Michaels thread rather than hihjack @Reed_Richards very helpful new one about their experiences.  I've been playing around with numbers to see if this would work for me.  My slight 'advantage' is that we currently have E7 storage heaters.  There is no mains gas nor any prospect of getting it.  My choices are therefore oil CH, G/ASHP or more/different electric heating (there are a couple of rooms unheated atm).  I’ve also considered A/C units. The NSHs are OK-ish because the house is occupied most of the time but expensive to run and inflexible. We have a coal stove and a wood burner that we find ourselves using out of necessity rather than by choice, especially when the weather is like it is now.  I'd like something more flexible, cheaper and greener.   

The house is a fairly modern bungalow; it has wall insulation and we've just had our green grant loft insulation top-up.  We are also getting new double glazed doors and windows.  We have lots of space outside including enough for a GSHP.    

Our EPC usage is c. 22500kWh, with about an 8:1 heating:DHW split.  For an ASHP my estimates suggest about £1300/year RHI and about £600/year saving on electricity.  I used an SPF of 2.9. If that's right and I can get everything installed for under £20k (that’s including radiators and pipework) I'd be interested.  I don't mind paying a bit for a better/greener heating system.  

For a GSHP, I get about £3200/year RHI and about £800/year saving on electricity.  I used an SPF of 3.7.  I was surprised at how much this is so I have the feeling I’ve done something wrong. That would make the 7 year break even installation cost about £28k but I’m a lot less sure how much a GSHP system would cost - I’m guessing at least £10k more than the AS option.

If anyone has any views I’d appreciate hearing them.  I’m sure others have done these calculations so a sense check would also be good.  

thanks

   

Reed_Richards

I was given an estimate of £17k as the cost of drilling the necessary boreholes for a GSHP.  You don't have to drill boreholes if you have a spare paddock you can use for an array of piping in shallow trenches.  But I do mean paddock, a large area of something that you can dig up like grass is required.  You also need a boiler room, or equivalent, to site a GSHP.
My old EPC reckoned 17.2 MWh per year for heating and 3.8 MWh for hot water.  This EPC was more than two years old and the second surveyor took a very optimistic view of my loft insulation thickness so the figures came out a bit less.  My actual annual energy consumption was about 21.5 MWh  per year assuming I got 10.35 kW per litre of heating oil.
I was quoted an SPF of 2.89 for hot water and 3.14 for central heating for the ASHP I installed.  That was for heating the hot water cylinder to 50 C and the input flow to the radiators to 50 C.    

shinytop

Reed_Richards said:

I was given an estimate of £17k as the cost of drilling the necessary boreholes for a GSHP.  You don't have to drill boreholes if you have a spare paddock you can use for an array of piping in shallow trenches.  But I do mean paddock, a large area of something that you can dig up like grass is required.  You also need a boiler room, or equivalent, to site a GSHP.
My old EPC reckoned 17.2 MWh per year for heating and 3.8 MWh for hot water.  This EPC was more than two years old and the second surveyor took a very optimistic view of my loft insulation thickness so the figures came out a bit less.  My actual annual energy consumption was about 21.5 MWh  per year assuming I got 10.35 kW per litre of heating oil.
I was quoted an SPF of 2.89 for hot water and 3.14 for central heating for the ASHP I installed.  That was for heating the hot water cylinder to 50 C and the input flow to the radiators to 50 C.    

That probably rules out a GSHP.  We have a decent garden but certainly not a paddock and the borehole costs makes a vertical array impractical.  I have a less than 2 year old EPC so I've used their loft insulation figures to adjust what they said.  Other figures are interesting, thanks.  

Reed_Richards

@shinytop I approached a company that manufactures and sells GSHPs and they were able to help me evaluate the heat collector alternatives and point to a company that could give me an estimate of borehole drilling cost.  So you don't have to take my word for it if you want to evaluate costs further.  I had to replace an external oil boiler and an ASHP could conveniently go where that had been whereas a GSHP would need to be inside the house or at least inside some enclosure and not knowing where that could be was another factor that put me off.  

michaels

For us a big issue was our energy demand is way over our EPC with the biggest difference being on how water (I seem to remember we use about 5x the EPC level) which then adversely impacts on the RHI plus with potentially hot water generally needing to be hotter than rads (unless it is really cold outside) this is even more inefficient to heat with a heat pump.

I was drawn to boreholes rather than trenches despite the cost not only because our garden is too small really for trenches but also because it seemed like they give a better COP throughout a long cold winter than trenches where the ground can be cooled and not reheat from the surroundings quickly enough.  I think they get  a higher RHI which may compensate for the higher cost, assuming you have the capital up front.

We also potentially have an issue that some of our pipework may be too small so it wouldn't just be a matter of upgrading rads. We have weather comp control on our current boiler so have a very good idea of the return temps we need to keep the house warm for a given external temperature.