Heat meters, or individual components, used for RHI purposes must comply with Class 2 accuracy requirements;
- As set out in Annex I to the 2004 Measuring Instruments Directive (MID) (2004/22/EC), Annex MI-004 of the MID, and within accuracy Class 2 as defined in Annex MI-00470.
- OFGEM will also accept other methods of demonstrating compliance with Class 2 requirements, please see the full guidance for more information.
Heat meters must not be tampered with to affect the readings and must comprise;
- A flow sensor (or meter) to determine the volume of fluid which has passed through a pipe within a given time period,
- A matched pair of temperature sensors (such as two thermocouples) that are calibrated together as a pair to make sure the temperature difference between the input and output of the system is measured to the stated accuracy level, and
- A calculator/digital integrator (though in some systems a Building Management System may take the place of the integrator) – a device which uses the information provided by the flow meter and the matched pair of temperature sensors to calculate the heat energy being transferred.
As part of the accreditation process OFGEM will also ask for (for each heat meter):
- Manufacturer, model and serial number or, where the components of the meter are purchased separately, the serial number of the flow meter component
- Brief product description
- Meter reading and the date take
- Applicant‘s confirmation that all meters were appropriate, installed in line with manufacturer‘s instructions and calibrated prior to use.
Complex Metering; Please read the guidance in full for more information on important updates to complex metering e.g for district heating schemes;
- Additional information for systems with more than three RHI-relevant meters
- Meter placement: simple and complex installations
- Meter placement for “complex‟ installations where the heat transfer medium is a liquid (i.e. not steam)
- Metering heat where there are multiple buildings (district heating schemes) An important change relates to heat lost in transportation between buildings is not an eligible purpose, so will not be included in any claim for payment. The simplest way to achieve this is to meter each building individually.
- Location of meters on boilers with heat recirculation
- Shared meters, installations in series, metering by difference, installation of meters
Schematic diagram; Applicants will be required to provide a schematic diagram of the installation and the heating system of which it forms part during the accreditation process
Independent report on metering arrangements; Where an installation is classed as complex for RHI metering purposes, OFGEM will require an independent report by a competent person. A competent person may be;
- An experienced and suitably qualified engineer
- Has experience and expertise in flow measurement and heat/steam measurement systems demonstrated by training and development records
- Has a relevant background in energy, utilities, building services, heating system design, heating system operation & maintenance
- Is covered by Professional Indemnity Insurance of at least £1m,
- Is unbiased and impartial.
They must visit the installation, sign a declaration, confirming that they meet the competency criteria and that the information provided in the Report is accurate to the best of his or her knowledge. A competent person is unlikely to be regarded as unbiased and impartial where, they are;
- An employee, of the owner or heat user;
- Related to the owner or heat user;
- Contractually obliged to author Reports exclusively for a given owner;
- The submission of the Report could have a material impact on a significant portion of his or her income.
What Should the Report Cover? A Report template is available here http://www.OFGEM.gov.uk/e-serve/RHI/Pages/RHI.aspx
This is a summary of the RHI Guidance, please be sure to read the Guidance in full before making an application.