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Changes to regulations for domestic RHI now in force

Posted by Cathy Debenham on 12 February 2015 at 2:08 pm

Rules about the sustainability of biomass fuel and the following changes to the regulations for the domestic Renewable Heat Incentive (RHI) came into force on 5 February 2015.

Cooker stoves

“Cooker stoves” are biomass stoves with a back boiler that are predominantly designed for space and hot water heating but can also be used for cooking. In these products the heat generated for cooking is incidental to, and cannot be controlled separately from, heat generated for space heating or hot water heating. 

The regulations came into force on 5 February making “cooker stoves” eligible for the domestic RHI, as long as the product and installation meets all other scheme requirements (further detail about other scheme requirements can be found in Ofgem’s Essential Guide for Applicants).

This change does not affect range cookers more widely; products designed for cooking will still be ineligible for the domestic RHI scheme, except where they meet the criteria of a “cooker stove”.

If you have a “cooker stove” that was installed before 5 February 2015, including installations before the 9 April 2014, you will have until 31 July 2015 or 12 months after the date your heating system was fully installed and tested (whichever is later), to apply for the RHI.

High temperature heat pumps

High temperature heat pumps are a development of existing air source heat pump technology. High temperature heat pumps can operate at temperatures as high as 80C and can be suitable for use in properties where it is not appropriate to change the radiators or use under-floor heating.

The regulations came into force on 5 February 2015 making high temperature heat pumps eligible for the domestic RHI, as long as the product and installation meet all other scheme requirements, including the minimum efficiency levels represented by a Seasonal Performance Factor of 2.5.

Changes to the MCS Heat Emitter Guide mean that high temperature heat pumps installed from 21 November 2014 may now be eligible for the Domestic RHI. You may only have a short window to apply for the RHI, as the deadline for application will still be 12 months from your systems commissioning date, there will be no extension for “legacy” installations.

Properties made up of multiple buildings

The regulations have been clarified to make it clear that heating systems that provide heat to properties with more than one building can be eligible for the domestic RHI.

Examples of systems providing heat to multiple buildings that would be eligible include:

 A dwelling plus swimming pool in annex

 A dwelling plus garage or outbuilding

 A dwelling plus shed

 A dwelling plus a commercially used building e.g. an office annex or stables

RHI payments continue to be based on the heat demand on the dwelling’s Energy Performance Certificate, as heat going to the ancillary buildings is not eligible for RHI payments.

This payment method means that in the final example, where the other building has a commercial use and the system is therefore also eligible for the non-domestic RHI, the owner might find it better to apply for the non-domestic RHI.

If the heating system provides heating for multiple dwellings (i.e. a district or community heating system) the system is eligible for the non-domestic RHI rather than the domestic RHI. 

Microgeneration Certification Scheme standards

The Microgeneration Certification Scheme (MCS) has published updated installation standards for heat pumps (MIS 3005) and solar thermal (MIS 3001) and an updated Heat Emitter Guide (MCS 021). These standards are referenced in the RHI regulations and we have updated the regulations to refer to the new standards.

There is a transition period for the MCS standards and if your heating system is installed in that period it can be certified to either the old or the updated standard.

You still have 12 months from commissioning of your heating system to apply for the scheme.

Registered social landlords and green deal assessments

Registered Social Landlords (RSLs) can now apply for the domestic RHI without a Green Deal Assessment. They still need to have an Energy Performance Certificate that is less than two years old so that RHI payments can be calculated.  

Biomass sustainablility rules

The long awaited Biomass sustainability RHI regulations also came into force on 5 February 2015. They mean that RHI participants must meet the sustainability requirements from 5 October 2015.

This gives you eight months to fully understand the requirement and how to demonstrate compliance, and for suppliers on the Biomass Suppliers List (BSL) to ensure they have the necessary supply chain evidence in place to demonstrate they meet the land use criteria. A detailed information sheet for biomass customers is available here.

In addition to these biomass sustainability requirements, participants on the non-domestic RHI will still need to ensure that the fuel used is in line with their RHI emission certificate for their installation, including ensuring that the moisture content does not exceed the maximum moisture content specified.

Photo Liz West

More information about the Renewable Heat Incentive (RHI) on YouGen.

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11 comments - read them below or add one

Cathy Debenham

Cathy DebenhamComment left on: 10 March 2015 at 9:52 am

Hi John

It's true that MCS has agreed standards for thermodynamic panels. I saw someone from MCS last week and he says that no panels have been approved under these standards yet (and a quick look at the MCS website just now indicates that Energie panels haven't been approved). I'd take any claims of them being included in the RHI in the near future with a huge pinch of salt. I'm not seeing any indication of it. Don't go ahead on that basis, as you may well be disappointed.

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Johnd44Comment left on: 9 March 2015 at 4:29 pm

Hi Cathy,

I just had a further chat with the Company "Energie" in Cambridge and I understand that MCS have now approved these thermodynamic panel systems under the Sun Assisted Heat Pump (SAHP) rules but they have not been added to the approved list until RHI have also confirmed elegibility and the rate of payment.

I was also told that it is highly likely that, like PV systems, as soon as they were approved the prices will go up.

I still think I will wait to get the system re-installed as I am not happy to pay for a new system when I already have one but it has now been superceeded and cannot be re-installed.

Regards, John.

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peedeeComment left on: 9 March 2015 at 3:59 pm

Cathy@ 3 March,

May I assure you that 'such heat pumps' are all too common already, even if someone has recently awarded them an acronym of their own.  You can install one very easily by attaching a pump to the radiator circuit from a fossil-fired boiler.  It is what installers do to cheapen the job but there are nasty consequences for the consumer :-
1:  The pump can consume far more electricity that it should,
2:  with the consequence that it costs far more to run than it should, and
3:  the installation fails to heat the house properly at the design minimum temperature.

During winter 13/14 I tested a pump that pumped at over 60C flow temperature at 5C ambient.  It had a tested CoP of 1.64 and ran continuously.  It cost far more to run than the oil boiler it replaced. 

The heat output of a pump is equal to the pump electrical power times the CoP.  If you halve the CoP, then you halve the maximum heat output.  Air-to-water pumps are rated at 7/(30/35).  Take a 4kW(electrical) pump with a rated output of 14kW (CoP=14/4=3.5) and make it pump at 60C and the heat output drops to about 7kW.

In the field trials report for December 2013 DECC reported that half the pumps operated below the SPF=2.5 value.  Half the pumps were not renewable and the primary reason is high flow temperatures.  I have formally proposed an amendment to MIS3005 to stop this nonsense.

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Cathy Debenham

Cathy DebenhamComment left on: 9 March 2015 at 11:08 am

@Johnd44 I'm researching a new blog at the moment which will answer this question, as there has been some progress on MCS accreditation for thermodynamic panels. I hope it will be ready this week or next, so keep an eye open for it.

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Johnd44Comment left on: 6 March 2015 at 5:18 pm

Hi Cathy,

Many thanks for your response, I still have a question on this so I hope you do not mind me following up again.

I have just looked on the eligible products database for the RHI and see that the Energie Thermodynamic product is specifically stated as Inelegible which is useful as this clearly states the position.

However on the MCS data base it states : "CEN Solar Keymark certification is recognised by the UK Government"  and on the Solar KEYMARK database the Energie Thermodynamic Panel holds a valid certificate issued in February 2015.

What I do not understand is why if the UK Government recognises the CEN mark why the MCS and RHI do not also recognise it. I accept that the technology is different to other Solar water heating sources but I can find no explanation as to why it is refused recognition.

My experience has been very good in application, unfortunately my supplier has gone bankrupt and I now find that his work was not to standard but this is another issue, the system worked fine.

I almost feel that this is like the Ostrich burying its head rather than taking a new technology and then testing not against a standard that does not apply but initially to identify what it actually does.

Regards, John. 

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Cathy Debenham

Cathy DebenhamComment left on: 3 March 2015 at 12:55 pm

Hi Johnd44

Thermodynamic systems are part air source heat pump and part solar thermal and are not currently eligible for the domestic RHI. From conversations I've had recently with DECC and MCS I don't think they are likely to be in the near future. So it sounds as though the salesman if misleading you. 

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Johnd44Comment left on: 3 March 2015 at 10:58 am

Hi Cathy,

Do the changes that have been announced also include what were described as "Thermodynamic Water Heating Systems" I have had one of these systems for 18 months but it seems that it is not correctly installed and I am now told I will have to have it modified to qualify for the RHi payment. The cost of modifying is very significant and I am not sure if I will bother to have it done or if there is any real return.

I like the idea of Green Energy but I need to be sure that the system is qualified and can meet the terms of the RHI.

Where can I find out the true situation and not just salesmen's speel.

Many thanks for all your help.


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Cathy Debenham

Cathy DebenhamComment left on: 3 March 2015 at 10:21 am

Hi Peedee

I'll do some digging to see if such heat pumps exist. It seems strange that DECC would change the rules if such a product doesn't exist.

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peedeeComment left on: 2 March 2015 at 3:16 pm
'The Domestic Renewable Heat Incentive Scheme (Amendment) Regulations 2015
As a consequence of the changes to the technical standards, high temperature heat pumps are now eligible for the scheme.'

Wrong if the SPF is less than 2.5, which it will be if the pump outlet design water temperature is greater than about 50°C.  A pump limited to 50°C could not be a 'high temperature heat pump' capable of operating at 65°C or even 80°C.  The source of the problem is that the Amendment Regs 2015 conflict with the Regs 2014 because somebody forgot about the consequences of Carnot's Law (websearch 'wikipedia carnot law').

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peedeeComment left on: 2 March 2015 at 1:00 pm

The section on 'High temperature heat pumps' contains a further problem:-
'making high temperature heat pumps eligible for the domestic RHI, as long as the product and installation meet all other scheme requirements, including the minimum efficiency levels represented by a Seasonal Performance Factor of 2.5.'
The [Heat Emitter Guide] provides an indication of how efficient your system should be dependent on the intended water flow temperature (which we all know is the key factor in determining the efficiency of a heat pump system).
the RHI has a minimum SPF requirement of 2.5 which, using the heat emitter guide, will mean your system will have to be designed to run at 50°C water temperature and your radiators sized accordingly.

If you need to get the design water temperature down to 50°C to attain the minimum SPF of 2.5, then using a higher design water temperature of 65°C, let alone 80°C, is impossible whilst being eligible for the domestic RHI.  This section on  'High temperature heat pumps' appears to me to be a nonsense, but maybe there is a rational explanation?

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peedeeComment left on: 28 February 2015 at 3:10 pm

p { margin-bottom: 0.25cm; line-height: 120%; }a:lCathy,

Your reference to 'High temperature heat pumps' in recent legislative changes needs to be accompanied by a severe financial risk warning to any consumer considering these devices. Even the MCS Standard referred to in :-

The Domestic Renewable Heat Incentive Scheme (Amendment) Regulations 2015 (SI 2015/143)

carries this very clear warning :-


Date: 21/11/2014


Air source heat pump (ASHP) systems including Very High Temperature (VHTHP) and CO2 heat pumps


The selection of Very High Temperature Heat Pumps (VHTHPs) should be avoided unless the limitations of the system design offer no alternative other than to use a higher than normal flow temperature; for example listed buildings or design limitations preventing the use of larger heat emitters. If offering a VHTHP, evidence of this work and design, including an example for a low temperature system, should be shown by the installer and changes to the efficiency explained to the householder allowing them the choice to select a heat pump in these circumstances as being able to operate at Very High Temperature conditions as specified in MCS007. The maximum flow temperature selected for very high temperature heat pumps shall not exceed 65°C at the outside design temperature given in table 2.


1: The MCS Standard limits the temperature to 65°C. I have not found the source for 80°C as yet.

2: As ever with heat pumps, the cooler the outlet temperature of the pump, the better.

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