@mairia Indeed, ours is on the side wall in the airing cupboard and would be easier to use if I had normal vision - but I have very limited vision. However good ones’ vision might be, it wouldn’t make up for such an appalling design and as for Onecta (what is a One cta anyway?) app, it ought to win a prize for the most rubbish implementation of available data (never mind consumption data accuracy!) The MMI may be more use to the installer but is of very limited use to the homeowner I feel. Regards, Toodles.

Posted by: @majordennisbloodnok

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I agree with @editor, and would also suggest that it may be worth having a quick chat with the Citizen's Advice Bureau to see how feasible it might be even with this amount of elapsed time to put a claim into the small claims court

The issue won't need to go to the Small Claims Division of the High Court.

The written evidence referring to a 9kW and an 11kW unit is sufficient for this to be addressed under the Consumer Rights Act.
That Act is administered by the Citizens' Advice Bureaux anyway, so you should make it a priority to contact them.

The CAB have options for both Arbitration and Alternative Dispute Resolution (ADR).
Neither is an onerous as filing a case with the Small Claims Court, and you won't need to pay for legal advice either.

At this stage I suggest you don't restrict what you might wish to claim for.
The Consumer Rights Act covers both Goods and Services.
The CAB Advisor may wish to pursue both possibilities... the physical installation of the 'wrong' unit, and the survey work/administration which gave rise to the problem.

For everyone responding to this topic, can we please bear in mind that the analysis and comments we make here are themselves relevant evidence.

Our discussion can be used by the CAB in work to seek a resolution under the Consumer Rights Act.
So we need to keep our responses clear and to the point.

Thanks.

Posted by: @mairia

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I did pore over all the documentation I have, and was definitely not given a copy of the heat loss calculation.

That's a failure to comply with Part-L of the Building Regulations.

The householder must receive all relevant documentation, and it must be site specific.
You should also therefore have a full system diagram of what's actually installed in your home,
plus instructions on how to operate and maintain the system so as to minimise the amount of energy (electricity) which is used.

Note too the requirement for a written Commissioning document.

As each house is different, the system components will vary.
Thus the Installer has to construct a commissioning schedule for your specific property.

That will necessarily include a final section in which the system is configured to be optimally efficient.
It isn't possible to do that in a few minutes as a tick-box exercise.

@transparent thank you, I will add that to my to do list. Have you any thoughts what I might hope for as an outcome if the unit installed is actually the appropriate one?

Would it be reasonable to expect the installer to meet the cost of an alternative provider to carry out a new heat loss calculation and assess the set up of the system? As I think that's probably what I feel needs to happen and was prepared to meet the cost of that myself.

Posted by: @mairia

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Would it be reasonable to expect the installer to meet the cost of an alternative provider to carry out a new heat loss calculation and assess the set up of the system? As I think that's probably what I feel needs to happen and was prepared to meet the cost of that myself.

Yes but... all you will get is another exercise in GIGO theory with the same variability as the original.  It then becomes the view if one installer vs another.   I don't see how this helps you and it consumes your energy and the residual goodwill of the installer.

Better in my view at this stage for you to pinpoint the problem with experimental evidence and then he expect the installer to fix it.  Like it or not there are unknowns in buildings which can only be resolved by experimental measurement.

I looked at the spreadsheet.  It's great to demonstrate cop, well done, great data recording I wish I were that diligent.   I presume figures are from mmi so measured at heat pump?  It doesn't do anything for the room temp problem though, can I suggest you add some info going forward to track that.  You need as a min iat, oat, ft, ideally at several times during v cold days as well as some spot measurements at other times.

Posted by: @mairia

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And I'll contact MCS, I didn't realise they would have a copy of the heat loss document. Also can I say thank you so much to all have responded so helpfully today. I was feeling quite demoralised with the dismissive responses from the installer.

And if MCS don’t have one on record that’s an issue because MCS can’t/shouldn’t issue a certificate without one, and I would then put MCS on the spot asking how this could have happened. Definitely keep me posted on the outcome of this conversation.