Is "air" an "alternative" fuel ?

Adding to @M.isterW‘s remarks, I’d point out that gas users are benefitting from enormous government subsidies by virtue of the Energy Price Guarantee. Those who can’t use gas aren’t, so the AFP helps redress the balance. Most households with heat pumps, however, will already have enjoyed grants from the same source well in excess of the £200 now being distributed, so could it be that they’re not regarded as being quite so deserving of further help? 

Hi @Firedog and @M.isterW , thanks for your considered replies.  I agree with you and indeed I qualified for Ofgem’s Domestic Renewable Heat Incentive Scheme (now closed), so I am getting a repayment on my original ASHP installation costs, but as anyone will tell you this falls well short in terms of repaying the actual costs of adopting this technology to heat your home.  I did think the ASHP would be more efficient in a purpose built home (it was part of a new build), but the recent increase in electricity costs (even limited by the EPG) have highlighted how prone ASHPs are to loss of efficiency in temps below 3 degC.  So I guess my question was born on the back of this and whilst it was a conscious decision to support renewable technology in an “Off-Grid” location, recent market disruption has made me question this “go green” decision.  Furthermore your replies prompted me to look into the comparable costs of running home heating boilers on what the Government have deemed “alternative” fuels and the following analysis by Nottingham Energy Partnership reveals that running an oil boiler on domestic kerosene (i.e., your bog standard heating oil) costs 9.23 ppkWh vs. an ASHP at 14.23 ppkWh .  Allowing for the assumptions in their analysis (which may bring these values closer together - or indeed further apart) - the general observation is that it is cheaper to use most of the Governments deemed “alternative” fuels, than an ASHP to heat your home at the moment!  Which isn’t good news, if you are trying to promote ASHP’s as an affordable way of lowering CO2, i.e., one of the Government’s main policy planks towards Net Zero in domestic home heating.

https://nottenergy.com/resources/energy-cost-comparison/

Anyhow, I kind of got diverted there, so forgive me.  However I think these cost comparisons only go to reinforce the view that anyone using an ASHP to heat their home in an “Off-Grid” location, should feel relatively short changed under this Alternative Fuel Payment mechanism, as it doesn’t include them.

Do you know what COP you’re getting from your ASHP @Corgimajor  ? It’s likely that if it’s not around 3.5 to 4 you’ll be quite cross. Mine has been around 2.25 so I certainly am. However I am very hopeful that I can find the reason and improve things.

Hi @juliamc it is rated on the MCS Certificate as having an SCOP of 3.95 at a flow temp of 35 degC.  I am unable to do much in the way of checking this efficiency value as I don’t have a dedicated heat meter as my ASHP only provides hot water for UFH and the DHW is provided via another system.  I do have a dedicated Electricity (input) meter for the ASHP operation and I’m going to start monitoring this better (relative to outside air temp).  Reading lots of stuff on-line, there is clearly a correlation between Air Temp and ASHP performance, but it is hard to pin it down, particularly as a lot of the reports are from the USA where Air to Air is more popular than Air to Water.  I imagine like all referenced performance test data (used to compare performance on a “like for like” basis) this performance is hard to replicate in the real world where variables like:

location from the house, outflow temp, defrosting temp setting and timing interval settings, condition of the property (i.e. air tightness), heating mediums (UFH or Radiator), whether the ASHP application is dedicated heating or duel heating and DHW, etc.,

are all going to have an impact on the efficiency of the system.

I guess as more people start having ASHP’s installed the more the efficiency of them will be come under scrutiny by consumer groups and other interested parties.  I think there will be an unsurprising general consensus however that they aren’t as efficient as their COP test rating suggests and that performance does drop off when it gets much below 3 degrees C.  Living in North Cornwall this is thankfully a rarer occurrence, but if I was living again in a rural part of central England where temps get below freezing a lot more regularly in the winter, I would be more concerned about how much an ASHP was going to cost me - particularly nowadays!

The following chart is a measure of how my own ASHP has been influenced by outside air temps during Dec 2022 and Jan 2023.  It is far from a scientific study as there were lots of variables influencing how our electricity consumption varied over this 2 month period (staying family guests over the holidays, more use of domestic appliances, etc., etc.), but still it seems reasonable to assume that the cold snaps we experienced over this period did decrease the efficiency of the ASHP.  NB.  one significant variable we avoided is the temp setting inside the house as we kept it at 19 degrees C - so the call for heat on the ASHP system over the period would have been fairly stable.

Excellent graph. We had temps of -7 on the coldest nights in December but I only ventured up to the loft to look at my heat pump controller once it had warmed up a bit. I know the cop fell below 2, averaged out over a number of days. What make is yours ? I can read off energy input and energy output from mine, for heating and hot water separately so I can calculate the cop from that, ie output divided by input. 
As far as I understand it, the cop figure is a measure of the heat pump’s efficiency and isn’t influenced by things like lagging etc. though that will of course have an enormous bearing on the electricity consumption. 
Are you using weather compensation? 

Hi @juliamc,  it is a Solis 11 (11kW) from Earth Save Products in Wallingford.  It is fairly agricultural, but inverter based, technology.  Chinese manufactured (surprise, surprise!).  No whistles or bells (rudimentary weather compensation).  It was very well installed (well protected from the elements, with a very short run for the well lagged service pipe work) -  so if I maintain it reasonably well it should last 🤞. 

Form launched

https://www.gov.uk/apply-alternative-fuel-bill-support-if-not-automatic