Thank you OpenEnergyMonitor: Octopus Daikin ASHP monitoring

Yay Matt!

My schedule has bedrooms at 18C, living room at 21C, is yours the same? That isn’t enough to account for the difference though.

Something less, I’m thinking. Extrapolating from @ColinS 's numbers for the 11kW against the MCS certification data for -2 for both, perhaps 6.2kW, which would be pretty dull. And that’s at 45C LWT… We’ll see.

Hi John,

Living areas are at 21c, bedrooms at 18c, bathroom at 22c, hallway at 18c and conservatory at 16c.

Hi @matt-drummer, apologies about the overlapped responses.

It’s a 9kW, and appears to produce a minimum of 4.5kW or thereabouts for about 900W input, at the current ambient temps (9C). I just got the instrumentation sorted yesterday, so I’m learning. But unsurprisingly, it’s the same as yours!

At the current 9C outside temp, it’s not cycling very much at that output. This is the output of the local EmonCMS MyHeatPump app since 12.00pm today. I suspect it’s under-radiatored, but right now i can live with it, I don’t think I’d want it any warmer, and it won’t go any lower!

I’m pretty happy with the rads, inasmuch as the place is comfortable so far (Reading climate). One of the bathrooms is very warm, so we’re drying clothes in it :slight_smile:. The rad schedule indicates that most rooms are oversized against the -2.2C computed heat loss, but then I don’t have to use the highest flow temp, which is a good thing.

Hi John,

No need to apologise.

I now have 12,000w of radiators at a delta t of 30c as I have replaced all upstairs.

Once I have finished downstairs I will have around 20,000w.

I am also running Speed Comfort fans on all the downstairs radiators at the moment.

Your is running quite well but in much shorter bursts than mine.

My house is currently at about 24c!

@ColinS worked out the minimum output 7c outside and a COP of 5 as being about 4,600w so you are correct.

By the looks of it you are radiator limited as I would expect based on your 10kW output at 50c flow.

I think my radiators can currently output around 3,600w at 35c flow so a COP of around 4

What settings are you running, maybe I can give it a try?

As far as I’m aware, there’s noting in the permitted development legislation that requires MCS installation, only the heat pump unit itself needs to be “MCS compliant or equivalent”

Unfortunately it’s not quite that simple.

The legislation has this paragraph:

" Development is permitted only if the air source heat pump installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020) or equivalent standards."

As the MCS standards seem to be the only available standards they are the ones that are assumed to apply.

The MCS standards ( say

IOW it has to be installed by an MCS contractor in order to be permitted development.

1 Like

Interesting, I would argue that the “or equivalent” would include heat pumps installed to an equivalent level as MCS but not necessarily by an MCS registered installer. In reality, minimum MCS standards are so low, they are not difficult to improve on! I.e. design to a COP of 2.8 but no requirement for ongoing monitoring to check this low bar is reached!


Exactly that @billt

Ian Rippin, head of the MCS, is on record as having a stated aim of ensuring that there is only one standardised way to install a heat pump and that it will be MCS that dictate that standard.

The intention of the rules was to allow you to follow a recognised calculation method and, if the estimated noise was acceptable, the heat pump would be permitted development.

MCS have very cheekily, but very deliberately in order to secure their position in the world, written the requirement that you use MCS labour to install the heat pump into the standard. This forces you to employ MCS labour to install your heat pump if it is to be installed under permitted development.

Ian Rippin and his buddies are the friends of anybody except for himself and those large companies that seek to (a) put up barriers to make market entry more difficult for small players and (b) want a standard that ensures nothing other giving them a piece of paper to hide behind.

They’re the perfect partners for our tentacled friends from this perspective. If you’re large you can automate (and indeed ignore; as the MCS wouldn’t dare suspend your registration) production of all the box ticking paperwork. If you couldn’t care less about the performance (because you’re in the business of selling electricity) then you want to have something that you can defend yourself against when the customer notices that not everything you do smells of roses. Perfect buddies.

The days of MCS representing the pioneers of a new industry and seeking to share technical knowledge and best practice etc to improve results such that the industry can grow were over some time ago. They now serve the corporates seeking to limit the expected standards such that they can make bank.

There won’t be a new standard that government recognises. MCS is “deemed” fit for purpose by the government regardless of reality. The emperor has clothes. Any new standards are subject to scrutiny before being “deemed” fit for purposes and therefore have a higher bar to meet / can’t get off the ground.

What I would like to see is a performance related pay option for funding. “Install your heat pump. Prove after a year (or two, if you got it wrong the first time) that you did it right by metering it. If you achieve say 80% of the target sCOP then you get your VAT back and your £7500 taxpayer rebate for installing it.”

Now the DIY crowd can crack on and all your local plumbers can crack on.

Octopus et al can still participate, and indeed advertise the “after rebate” price as the price to the consumer, and they’ll simply have to set aside a pot of money for fixing their f**kups if they want the £7500 and the VAT back. Or they can take a £2500 grant for an “deemed” F-grade on their exam paper rather than an A-grade etc. :wink:


That is by design.

The scheme is meant to defend installers against claims of having done a bad job. It is not meant to defend the consumer against installers doing a bad job.

Take a look at how is is used:

They commit to absolutely nothing in terms of the outcome the consumer receives other than not breaching any of the MCS standards.

No words on planning/design/commissioning there either. Only the physical installation. (i.e. they’re offering no commitments on anything other than how the pipes are nailed in)

Or indeed take a look at the liability clauses:

Zero liability for consequential losses. (i.e. if if doesn’t do what it said on the tin and costs you a fortune to run then tough)

Absolute limit on liability of £7500 (except for personal injury/death). So even if they set fire to your house and cause £250,000 of damage the limit of their liability is £7500? Really?

These are ridiculous clauses to have in a consumer contract and signal just what lengths they deem it necessary to go to in order to defend themselves against the consequences of their works.

The MCS standards are…as low as they can possibly get away with…to match with contractual clauses that are as close to an “unfair term in a consumer contract” and the minimum requirements of RECC etc as they dare to be.

Not. Your. Buddies. :wink:


Something I’ve just spotted, a difference between the 2022 survey vs 2023 survey is P1 vs K1 on the rads.



Quite the difference. I’m not well informed enough to know which is most correct.

P1 also known as Type 10, is a type of radiator with 1 radiator panel and no convection fins. K1 also known as Type 11, is a type of radiator with 1 radiator panel and 1 set of convection fins.

Check your existing radiators; do they have fins on the back (K1) or not (P1)? Fins give more output.

  • P1 H600 x L1400 = 478 W
  • K1 H600 x L1400 = 705 W

2022 survey proposed replacing some of those P1s, while 2023 thought existing K1s would be fine for the heat loss of those bedrooms. One of the surveyors mis judged the existing rads.

Definite fins, so K1.

There’s quite a difference on the heat losses of some rooms.

Lounge was 1,252w and now 1,548w (+23.6%)
Kitchen was 502w and now 961w (+91.4%)

Has your house changed?

If not the heat losses can’t both be correct?

No changes…From the kitchen there’s a large double glazed window and large glass patio door to the conservatory, along with a wooden door to a utility room where the boiler lives.

Does excluding the conservatory this time mean the calcs would show more heat loss for the kitchen since the conservatory is now unheated?

Probably, yes.

What about the lounge?

I have received this today - our house has an EPC of B89 ( a bit of a clue to the insulation?) and no mention of actual heat loss used to determine heat pump size.

I’ve reviewed the heatloss calculations in depth and there is nothing wrong with the walls/loft/floor. The only thing that may of thrown them off is the air change rate which for the age of the property (1960-2000) we used an industry standard, however this may not of taken into account the reality that the customers property may be more insulated and airtight than the average property of that age band and wall construction which can be attributed to better build quality.

The hp spec’d was a EDLA09 which is correct for the baseline calculation that we do on all HP surveys. He is only a few 100 watts above the maximum output of the 8kw smaller unit at -2.3 external temp.

The house is more airtight than average and this may not have been fully calculated for as we use the CISBE standard air change rates for this property age band as does every other installer. and we calculate on worst case scenarios as to not undersize the HP.

If you would like, we can look at installing an EDLA08. However, we would not be able to change the unit again if the unit is not performing in the coldest months of the year as it would be going against the original design.

1 Like

I have just noticed another mistake on my radiator schedule, my P-Plus radiators aren’t, they are K1s.

I can’t think of a reason for the lounge. Unless one took more care measuring/accounting for the bay window than the other!

Cheeky f**king so and so claiming that every installer uses the “no glass in the windows” air change rates based on property age rather than attending site and surveying the property with their own eyeballs to pick a different figure.

That sounds like a peace offering.


  • You’ve since mucked about with the install (from their perspective) by adding the heat meter / changing radiators

  • Our tentacled friends pay their lawyers more than their installers and have promised you absolutely nothing contractually as far as the end result is concerned

Perhaps “respectfully disagree with the assertion that every other installer uses age-default air change rates rather than surveying the property in person and selecting an appropriate air change rate, and respectfully disagree that there is nothing wrong with a heatloss calculation that bears no resemblance to there not being two living rooms etc” but take them up on that offer to exchange the unit for one that the available data shows is more appropriately sized?

1 Like