The Big Secret To Achieving High RHI Payments (No One Will Ever Tell You)

Government subsidies like RHI payments can be baffling, but there are some simple metrics that can have lasting financially beneficial effects on both the homes running costs and the amount of money you receive. If you want to learn the secret to achieving high RHI payments, read on…

The most significant factor that affects heat pump payments is the flow temperature of the system. In simple terms the higher the flow temperature the less money you will be paid because the heat pump is deemed to be running less efficiently to heat your house.

RHI Payments – Reduce The Flow Temperature

On this premise if you can reduce the flow temperature of the heating system you can maximise your payments. At present the lowest flow temperature underfloor heating systems being installed (with 100mm pipe centres) run at 35C. Indeed the heat emitter guide used to calculate an installation’s star rating tops out at 35C as a 6 star installation. According to the government they won’t pay you any more money for an even more efficient system.

If you are thinking of underfloor heating throughout your new build or refurbished home, you could easily install such a low flow temperature system.

So this got us thinking…and we decided to run a few simple calculations to find out how much more money you would be paid if you designed your underfloor heating system for 35C rather than the maximum 50C flow temperature allowable under the current RHI scheme.

Our simple example assumes a 4-bed house that uses 30,000kWh of heating energy per year.

ASHP Example

Tariff = 7.3p/kWh

Flow temperature 50 35
SPF 2.7 3.6
Annual RHI income £1,379 £1,582
Total 7-year RHI income £9,653 £11,072
Running cost £1,612 £1,251

Annual running cost saving difference = £361

Annual RHI benefit difference = £203

Once all is said and done there would likely be an additional 7 year financial benefit of £3,948 between two systems designed to run at different flow temperatures!

Yet the cost of putting in additional pipe (with 100mm pipe centres) would likely to be only around £1,500 including additional labour and parts. The mathematicians amongst you will clearly see a profit even after that particular adjustment.

If we undertake the same calculation for a ground source heat pump (18.8p tariff rate) it reveals an additional 7 year financial benefit of £4,109.

So now you know the hidden secret of maximising your RHI payments, take heed and make sure you talk to your installers or even better call us to ensure you make the most of the scheme.

Any questions? Leave a comment below if you have any further questions about RHI payments or other government subsidies.

Doug Johnson

Doug is a chartered mechanical engineer and has had the pleasure of being involved in the UK renewable sector since 2008. With wide-ranging operational and design experience in both the domestic and commercial sectors across a wide range of recognised technologies he hopes to be able to share his experience to help enlighten and save you hassle along the way.