Hey all, 

I just wanted to put in an update and again ask for some advice. 

I got my radiators changed upstairs to a bigger size - thinking that was the issue.  

Mitsubishi engineer came out in May. He found several flaws with the installation but did not hand me to have the report as I did not pay for it. The developer paid for the callout. He fixed some pump attached to the cylinder. The night he came he got the heating working full blast upstairs and the heat pump stopped making the high pitched noise. The second day, things were back to where they were. No heating upstairs, high consumption ( COP of 3 at very very best with super hot weather), horrible noise coming from heat pump etc.

After another 2 months of calls and emails, I decided to log in a complaint with NHBC and call my solicitor. The developer then rang me and said he has no clue what to do / how to repair it and he does not understand what mitsubishi is suggesting. He said he only installed the heat pump as he was building the house for himself and he was advised it is the best option, but his gas engineers have no experience with renewable enenergy. He is willing to swap my heat pump for a gas boiler....

Well isn't that going backwards and sideways? Seems like a waste, but then again it is not working as it should and I am very panicked like in game of thrones that winter is coming and I will have an 11 months old freezing in his bed and pay about £500 /week for this scenario. 

I am reluctant to keep the heat pump, simply because the Mitsubishi Engineer that came made a comment about the high pitched noise " i've never heard one so loud. I have updated the system, but I was advised by techical team that if the noise comes back, then the unit needs changing". 

Heat pump is out of warranty ( explanation is somewhere in my posts above). So I will be out of pocked by a lot if I want to keep it and get everything fixed / changed .  I assume a new pump plus fixing is around 10k, even after grant?) . Developer is reluctant to do that as he said he can't fix it if anything was to go wrong as his people are unexperienced .He will sort out a gas boiler . 

What do you guys think? what would you do? get the gas boiler if you were in my shoes?Take into account  I have no money spare as I just bought the house and have a newborn, so can't really be spending what I do not have... 

Many thanks, 

Anca

@anca1808 

It's a shame to say it but if I were in your position under your circumstances I would snap his arm off for the gas boiler option.

Posted by: @morgan

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@anca1808 

It's a shame to say it but if I were in your position under your circumstances I would snap his arm off for the gas boiler option.

Hmm

Before doing that I would want to be certain that there are no attendant liabilities related eg to planning permission or grants that the developer, who may not know about them, will foist on you and also I'd want to be certain that the problem is the heat source not the rest of the system.  If the rest of the system is at fault changing the heat source isn't going to fix it.

Something about liabilities and warranties isn't making sense and so I'm suspicious you don't have the whole picture.  What is the developers motivation, why is he offering anything if he doesn't have to?  And if he does have to then is he just trying to get you off his back whilst dodging other issues which will come back to bite later. 

I presume incidentally that there is a gas supply to the house so his offer is practical without you having to pay for a connection 

@anca1808 I have just reviewed the whole thread.

In summary it seems

you have several issues (undersized rads, inadequate insulation) which have been identified and fixed, albeit not yet tested because it's too warm.

The high pitched noise, if it's coming from the outdoor unit, is a problem with the outdoor unit.  The fact it's out of warranty is not your problem, it's a problem for the developer who sold you a brand new house which should work.  Whatever mitsubishi need to do to fix that, he should pay for, even if that means a new unit (which is about 4k retail not 10k btw, like for like swap, small change for a developer).  Actually heat pumps are basically assembled from pretty simple components so more likely it's a component swap.  One thought about this, could you check the top is level in both directions.  Out of level heat pumps cause failed fan bearings which can certainly result in a high pitched noise!

Also you say that the mitsi engineer identified several faults with the installation, have these been fixed?

It's impossible to tell from the posts whether the efficiency/consumption has improved or not because you didn't say much about what happened after the insulation was done.

I'm not sure whether you ever did the esential optimization job of turning all the trvs and thermostats to max and then adjusting the weather compensation curve down until the house is just at the right temperature with the heat pump heating 24*7.  This is fundamental and, until this is done, you really can't judge efficiency 

I think you switched to octopus cosy.  This tariff works well only if you adapt the way you use your high consumption electric appliances to avoid the peak hours and tweak your heat pump programming likewise (which is not straightforward).   If you don't do this then it quite possible you won't benefit or even that it will cost you more.  Because it's quite a complex tariff this isn't particularly easy to do unless you use a service like havenwise (only £50 per year and you get a free trial period I believe) to automate it for the heat pump, and are disciplined about when you cook, do washing and use a dishwasher if you have one.

Personally I wouldn't give up yet, if you can get the heat pump working efficiently, and there is no reason why you shouldn't, you will end up with a more comfortable,  house than one heated by a cheap gas boiler operating at a constant high flow temperature (which is what you will get), for a similar running cost.  And of course it's more climate friendly) However to do this will probably require a bit more systematic work on your part which people on this forum can help with.  I think most of the mysteries are now solved, so it should be pretty straightforward if approached systematically.

If you do decide to accept the offer of swapping for a gas boiler, I still recommend you take heed of my post above.  The developer is making you an offer to benefit him, not necessarily to benefit you!