The SPF for Hot Water means the Seasonal Performance Factor of the Heat Pump in Hot Water mode.
It is worked out in exactly the same way as the SPF for Space Heating in conjunction with the Heat Emitter Guide. It is based on your Hot Water Flow Temperature (for hot water only) so therefore, 55°C flow will mean an assumed SPF of 2.4. This has no effect on the RHI payments, RHI payments are based on the SPF of the Space Heating only.
For any further questions please speak to your Mentor on Freephone 01244 784 260 or email [email protected]