Should I recalculate my heat pump's SPF? My renewable heat incentive journey part 2
Posted by Tasha Kosviner on 4 July 2014 at 9:03 am
As the owner of an air source heat pump who received a renewable heat premium payment grant prior to 20 May 2013, I am in the second tranche of applicants being invited to apply for the renewable heat incentive.
The date from which the group is eligible to apply – July 9, 2014 – is fast approaching so I have been examining the eligibility criteria with a renewed vigour. I have had my green deal assessment and I have – through gritted teeth! – ensured that my loft insulation is up to the required 250mm.
But the other question that has been on my mind is whether I should have my seasonal performance factor (SPF) recalculated. As I outlined in this blog, the SPF is the efficiency rating assigned to your heat pump. This rating is based on the required temperature of the water flowing through the system. The lower the flow temperature required (in order to keep the house comfortably warm), the higher the system’s efficiency; the higher the system’s efficiency, the higher your SPF; and the higher the SPF, the higher your RHI payments.
At the time my heat pump was installed, and up until the launch of the renewable heat incentive in April, installers used a variety of different methodologies to decide a heat pump’s SPF. Because Ofgem is unable to ascertain the accuracy of these different methodologies, it has been decided that for the purposes of RHI, a heat pump’s SPF should be deemed to be the minimum 2.5, and your payments are set accordingly.
If you think your heat pump is more efficient that this, you can decide to have your SPF reassessed using the new industry standard, set by the MCS and outlined in their heat emitter guide. This is the standard by which all SPFs are now calculated and has been in use since RHI launched in April 2014.
The question is, should I? The reassessment takes all day and can be expensive – I’ve heard of one installer charging £250 – and the possible gains through an increase in RHI payments could be marginal.
I called my installer for advice and the short answer he gave me was that no, it wouldn’t make much difference to my rating. Firstly, since my system is linked to a combination of underfloor heating and radiators, it’s not as efficient as one run purely with underfloor heating.
Secondly, since my home is well insulated, the amount of renewable heat needed is fairly low (RHI is designed to make payments based on the amount of renewable heat generated ie the heat demand of the house).
Thirdly, even if my SPF went up marginally to say SPF3 this would only equate to an increase of around £40 a year. Since he charges £150+VAT for the assessment, it would take nearly four years to make it back and then with only three years left to run on my scheme my total gain for going through the hassle of reassessment would be a relatively small £120 spread over years four to seven.
Further questioning of experts connected with the Microgeneration Certification Scheme standards for heat pump efficiency, reveals that in most cases an SPF of 2.5 is a good achievement for an air source heat pump although ground source heat pumps, provided they are connected to a system capable of heating effectively at lower flow temperatures, are likely to achieve 3.5 or higher.
I think I’ll be sticking with 2.5 then.
This is the second installment in my RHI: a personal journey series. You can read the first installment here. I will shortly be posting on my experience of the application process too so watch this space.
From the blog
How is the SPF of my heat pump calculated? (Sept 2013)
If you have a question about anything in the above blog, please ask it in the comments section below.
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