Metering RHI Phase 1
Helping installers find approriate guidance on metering requirements for non-domestic installations
Phase 1 of the RHI requires that the heat output of the installation is properly metered.
The requirements are detailed in Ofgem's guidance documents.
Simple or complex metering
Installations are defined as requiring 'complex metering' where any of the following apply:
- Heat is delivered by steam
- Combined heat and power systems
- Heat used in more than one building
- Ineligible heat uses on heating system
Similar requirements apply for systems above 1MWth.
Other installations classify as 'simple metering'.
Meter placement
This is no substitute for reading the official guidance. As a rule of thumb:
- Simple metering can measure the heat produced by the renewable heat installation. This requires temperature measurement of both the flow and return pipes, and a flow measurement on one or the other.
- Complex metering needs the installation of several meters to be placed so that the useful heat delivered by the installation can be calculated.
Metering guidance
Volume 1 of Ofgem's Guidance document devotes the whole of Chapter 7 to metering. The contents are as follows.
Chapter 7. Metering eligibility requirements ............................... 67
Heat meters ............................................................................ 68
Steam measuring equipment (steam meters) ............................. 72
Additional information for systems with more than
three RHI-relevant meters ............................................... 74
CHP systems currently registered on the CHPQA scheme .......... 74
Meter placement: simple and complex installations ...................... 75
Meter placement for 'simple' installations..................................... 76
Meter placement for 'complex' installations where the
heat transfer medium is a liquid (i.e. not steam) ................ 77
Meter placement for 'complex' installations where the
heat transfer medium is steam ......................................... 80
Location of meters on boilers with heat recirculation ................... 82
Biogas-specific metering requirements ...................................... 82
Shared meters ......................................................................... 83
Installations in series ................................................................ 84
Metering by difference ............................................................. 84
Installation of meters ................................................................ 84
Schematic diagram .................................................................. 85
Independent report on metering arrangements ........................... 86
