Posted by: @transparent

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The CEO of MCS has appeared before the Select Committee on several occasions already.

For an afternoon of canapés and lattes? Is there a record and/or transcript of what was discussed? Would be curious to know why he was summoned. 

Ian Rippin, CEO of MCS, gave oral evidence to the Select Committee on Energy in Feb'25,
for which the transcript of oral evidence is available here.
The subject matter was retro-fitting existing homes.

He also appeared before the previous Select Committee in 2021 on the subject of Decarbonising Heat in Homes,
which is somewhat more relevant to us here on the forum.

The Committee Clerk tells me that a witness before the Select Committee will typically be speaking for 7-minutes.
That isn't very long, and usually allows each Committee Member to ask just a single question.

Given that situation, it's very much up to the general public to ensure that Committee Members are supplied with relevant facts/data in advance of such a hearing.

An MP can't ask a detailed question unless we've first briefed them.

Anyone can communicate with MPs on a Select Committee, irrespective of whether you are in their constituency.
Ie the usual rules of Parliamentary correspondence don't apply here.
This is usually done by writing to the Chair, but if another Committee Member has a particularly relevant skill-set, then contact them.

The topics which the Committee decides to investigate arise from these initial conversations.

@transparent, ooh, I'm going to go through the Retrofit failures one tonight!

As a complete aside, I've seen a few people on various platform have started call Ian Rippin, "Ian Rippin' Us Off" which is quite amusing.

@mairie - Your constituency member, Dr Zubir Ahmed MP, is a surgeon who also has an MBA.

He is Under-Secretary of State in the Dept of Health, with particular responsibility for Innovation.

As such we should expect him to be receptive to fact-based evidence presented to him.
Let's keep that in mind as we 'recover' your ASHP installation to the status it should've had when properly commissioned.
Keeping a diary of changes we recommend would be a good start, as would a photographic record.

As a Government (Junior) Minister, he doesn't sit on Select Committees.
The opposite is the case... he gets summoned by them!

Further update. I did send complaints to HIES and NAPIT. I'm not really clear what the role of NAPIT is over and above that of MCS and HIES, MCS said they are the certification body and I should contact them if concerned about 'compliance or the changes made to the certificate'. I fear the more bodies there are the less likely it is that any one of them will take responsibility for helping me. I'm not holding my breath! On the positive side, removing the overnight setback has so far seemed to have worked quite well for maintaining a comfortable indoor temperature in outside temperatures as low as -2. I've also blocked the 3 air vents in the garage and it definitely feels more comfortable in there. I did check the COP over a few hours on 2 cold days, it worked out at 3.5 on a day with outside temp around 7 degrees, 2.4 on a day with outside temp around 6 degrees. I wonder if the rounding of kW to whole numbers by the Daikin MMI as in the video from Toodles makes the data not very valuable over short periods. I've taken lots of screenshots from the app at various times to show inside temp, outside temp and LWT. Mostly LWT is close to what I would expect from the heat curve, with a few inconsistent readings. Some of those are perhaps when the domestic water is heating after a shower. I also do wonder if the outside thermometer can be a bit unreliable - it definitely gets confused sometimes when there is direct sunshine on the outside unit and I then have to turn up the water temperature on the app. The ASHP is on a southwest facing wall. Overall I'm hoping that the 9kW heat pump is the correct size which would be a huge relief, still maybe a question mark over radiator sizes/balancing and maybe system settings but I'll keep monitoring things. Thanks again for everyone's input and I will keep you posted.

Posted by: @mairia

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On the positive side, removing the overnight setback has so far seemed to have worked quite well for maintaining a comfortable indoor temperature in outside temperatures as low as -2

Thats good news and what might reasonably be expected if its close to the correct size.

Posted by: @mairia

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it definitely gets confused sometimes when there is direct sunshine on the outside unit and I then have to turn up the water temperature on the app.

OAT sensor needs to be out of the sun.  On a Vaillant its a separate sensor so you can position it correctly, sounds like it may be integrated on your Daikin, @toodles will know.  The sensor may be visible round the back (typically a steel coloured cylinder about 25mm long and 5mm dia attached to a wire).  In this case if you could apply some local shade it might help

Posted by: @mairia

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Overall I'm hoping that the 9kW heat pump is the correct size which would be a huge relief

I would say its more likely than not but of course only time will tell.

Once you are convinced its working correctly to keep the house warm we can take a closer look at COP.

Posted by: @mairia

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Some of those are perhaps when the domestic water is heating after a shower. 

... or during/immediately after defrost, which will be happening at night at present if your temps are anything like mine.

@jamespa Yes, the OAT sensor is situated on the back panel, near the top edge and in my case, it is protruding from the grill slightly and has a transparent tube over it for protection. As to accuracy, I find that +or- ~1.5 degrees is about as close as I find to other probes and weather reports including my local weather according to Amazon Echo (Mrs. A as we call it to avoid waking her at odd times). You are making good progress, keep us informed please! Regards, Toodles.

Well, no major progress to report as yet. HIES replied ''As design also falls under the remit of NAPIT, we must allow them to continue with your complaint to resolve the issues in question. Once NAPIT have closed your complaint, if there are any elements outstanding, please send us in the confirmation from them that they have closed their complaint along with what issues were not resolved by them.'' NAPIT replied on 26.11.25 that my complaint has been received and logged, once a Complaints Handler has been assigned to the case they will be in touch. I'll chase that up today. The installer responded to the Subject Access Request at the end of November with some design documents, incorrect statements of fact and more unsubstantiated opinion about me changing settings, I replied but have heard nothing further.

My system has been working much better since I cancelled the overnight setback. However on very cold days it is struggling, I think especially if there is significant hot water use - although there are only 2 of us in the house. Over the cold weekend it has been particularly bad with indoor temperature sometimes under 19 and regularly between 19 and 20. I would want minimum 20.5-21 for comfort. This morning lounge temperature was 18.8 degrees at 9am, -4 outside and LWT 48 degrees. At 10am LWT was 41 and I changed the offset to +10. At 10.45 it was 19 degrees inside, -1 outside and 39 LWT. I checked and it wasn't defrosting at that point. Inside temperature has crept up, now 20.4 at 1 degree outside (though outside temp perhaps an overestimate as it is sunny) and LWT 49. I haven't run the shower or bath today. I'm wondering about contacting the new service engineer for advice while the weather is cold, he did offer to take a look at it for me. I have lots of screenshots of the temperatures on the app. I find the whole thing quite puzzling. Could the pump be undersized, or radiators undersized? I would be grateful for any thoughts.

@mairia Firstly its good to heat that cancelling setback improved things most of the time.  Very cold weather is of course the strongest test.

Posted by: @mairia

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I have lots of screenshots of the temperatures on the app. I find the whole thing quite puzzling. Could the pump be undersized, or radiators undersized? I would be grateful for any thoughts.

Yes possibly to both but it could be config still.  Can you post some of the screenshot with explanations where appropriate.  What are your weather compensation settings and does your heat pump reach the specified flow temperature (according to the WC curve) in this cold weather or fall short?  Do you normally manually adjust the LWT or was today a one off.

One trick in very cold weather if things are marginal is to heat DHW on the immersion.  I am doing that at present and of course it gives a couple more hours for space heating.  I have a cheap nighttime tarrif so the cost is negligible.

Posted by: @mairia

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I'm wondering about contacting the new service engineer for advice while the weather is cold, he did offer to take a look at it for me.

If he is really good yes, however if hes not really good he will probably just mess things up.  Also there are only a couple more really cold days left in the current snap, so he will be able to declare it fixed whatever changes he makes!  Personally, given how far you have come, I would do some initial investigation yourself and it will stand you in good stead if NAPIT ever get their act together.

@jamespa thank you. I think you may be right about trying to work on it myself. I feel I get a different opinion from every professional I talk to! The Daikin option to boost water heating is Powerful Mode which seems to be a combination of heat pump and backup heater. There isn't any way to choose just the backup heater annoyingly, and the manual warns that there is a significant risk of space heating comfort problems! I have tried it a few times in recent days when running the shower but wasn't sure if it helped. Overnight I have the DHW set to heat to 50 degrees, it is possible to set if to 60 degrees, I wonder if that would be better in cold weather. I do have cheap electricity from midnight to 7am.

Weather compensation is set to 25 at 14 degrees outside, 50 at -2 outside. 50 is the maximum I can set it to. I occasionally adjust LWT for comfort, but in recent days have several times stepped it up when it has been cold and the LWT isn't what I would expect from the WC curve. The LWT seems to be quite variable in relation to the WC curve in this weather, which started me wondering about the effect of DHW use and/or defrost cycles.

I have the system set to run on pure LWT control rather than using the room thermostat, I find it gives a much more steady comfortable room temperature. But would changing to room thermostat in very cold weather push the system to keep the house warmer? All of this reminds me that I really don't love the Daikin controls - a common theme on the Daikin users FB group. This whole saga started when I was looking at the option of 3rd party controls because of that - I wonder if that is worth looking at again.

I've summarised yesterday's readings into a spreadsheet, there are a few occasions where the LWT is much lower than expected from the WC curve. And I didn't have significant DHW use yesterday. Thanks again for your very helpful input 🙂

@mairia, I'm staggered that NAPIT have not been in touch yet. Absolutely ridiculous! Please keep me updated on 'progress'.

I'm really looking forward to hearing what NAPIT say, and equally shocked (well, I'm not really shocked, but you know what I mean) that HIES have delegated this NAPIT given that a chunck of your complaint is misspelling. You were sold an 11kW heat pump, and had a 9kW installed, and then the installer changed the MCS documentation on the sly. 

Posted by: @mairia

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, 50 at -2 outside. 50 is the maximum I can set it to.

So theres a problem for starters.  This means that the FT flatlines at -2 which means that, when its <-2 it isnt high enough to deliver the energy you need, which would very likely account for the deficit when its very cold.

Posted by: @mairia

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But would changing to room thermostat in very cold weather push the system to keep the house warmer?

Probably not unless the Daikin has auto adapt for its WC curve and the auto adapt will push it above 50.  In the end unless the FT is high enough your emitters cant deliver the energy needed by the room!

Posted by: @mairia

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I have the system set to run on pure LWT control rather than using the room thermostat, I find it gives a much more steady comfortable room temperature

No surprise, many, including me, find that.  Every day at the moment my wife remarks how comfortable we are (operating on pure WC) compared to the days of thermostatic control and a gas boiler

The 50C limitation may well be an installer setting, not inherent to the heat pump, and if it is backup heater wont help because it will be governed by the same limit.  Here are a couple of screenshots from the Daikin LT (low temperature) Heatpump manual from which you can see that the concept of installer limits exist (as with many heat pumps).  You probably have a different heat pump but the control concepts will be near identical.  Have a look through the installation manual for your heat pump if you can find it online!

Posted by: @mairia

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I've summarised yesterday's readings into a spreadsheet, there are a few occasions where the LWT is much lower than expected from the WC curve. And I didn't have significant DHW use yesterday. Thanks again for your very helpful input

This could be because you caught it during defrost. 

I'm not sure why you are manually adjusting the set temperature quite so much, really it should be left and the WC curve adjusted if at all possible; manual adjustment is likely to lead to instability and reduced comfort as you are inevitably reacting 'too late' (thats why WC works - it reacts in time because it knows what's going to happen to the house due to the OAT).  If you do adjust it then no more than once in 12-24 hours!  

Posted by: @mairia

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Overnight I have the DHW set to heat to 50 degrees, it is possible to set if to 60 degrees, I wonder if that would be better in cold weather. I do have cheap electricity from midnight to 7am.

No to the latter if its using the heat pump.  What you are trying to do is avoid the heat pump having to spend time heating DHW, or at least reduce the time it does so.  There is probably a stand alone immersion heater on your cylinder which is the key to this.  It may be controlled by the heat pump or it may be totally independent.  On my Vaillant its totally independent, so I have just fitted it with a regular £15 immersion heater timer from Screwfix, set to come on a couple of hours before the heat pump DHW cycle so it effectively does a pre-heat.  I switch this to auto (so it comes on) when its super cold, the rest of the time its 'off' so no preheating takes place and the heat pump does the job.  However in many setups the immersion is controlled by the heat pump and in this case doing what I am suggesting may be a bit more tricky.

Hope that gives you a few more pointers.  If you can sort this out yourself, which I think you probably can, you will be much more empowered and confident with your setup.

Feel free to ask for further clarification.