@joninorkney 

Hi Jon. Sorry to hear about you installation ordeal. 

it sounds like you have a good idea of what needs to be done with weather compensation. 

Your installer either doesn’t know what he is doing or is deliberately pointing you down a more expensive route to make his life easier. 

High temperature flow, TRVs and thermostats are not the way to run a heat pump efficiently. 

You may have a problem with the size of your radiators when trying to run at lower temperature. 

I’ve not seen a Daiken so can’t help you with how to set WC up. Someone on here should be able to help or failing that have you searched on YouTube?

@bontwoody 

Hello bontwood. Thanks for your prompt response. The problem is that, from what I've read, the heat pump is not being controlled to work efficiently, but the plumber who installed it insisted that a high temperature heat pump is different and the installation is perfectly ok. 

I did look in various places for more information, including YouTube, but I couldn't find any information specifically about high temperature pumps. When I contacted Daiken about previous problems with the installation they weren't very helpful. They more-or-less said that it was the installer's job to sort them out. Jon.

@joninorkney

Yes, you can run high temp heat pumps just the same as any other kind but I think you need two things that may be missing [I'm no expert but I've seen this discussed in the Daikin Facebook group]

You need radiators sized for lower flow temperatures (bigger than usual in basic terms) and a way of controlling the flow temperatures/weather compensation curves, hot water schedules etc.  

This is usually done on ordinary Daikin heat pumps with a Madoka and controller   this is a Heat Geek video on using them. I'm not sure how you access the controls on yours but I do know that your installer is talking crap when he says 'you don't need it'. People do run high temp heat pumps at lower flow temperatures. 

Look at this article that specifically mentions your heat pump 

Do you not have all the manuals? You should have access to the Daikin website and app (which is famously naff but better than nothing.) If I was you I'd ring Daikin and ask. 

Hopefully, others will come along who know more than me - what a rotten deal from your installers. I'm sure it is solvable with the right information. 

It may help to join a Facebook group or two. There's a Daikin group and maybe a more general ASHP group. 

Posted by: @joninorkney

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@bontwoody 

Hello bontwood. Thanks for your prompt response. The problem is that, from what I've read, the heat pump is not being controlled to work efficiently, but the plumber who installed it insisted that a high temperature heat pump is different and the installation is perfectly ok. 

I did look in various places for more information, including YouTube, but I couldn't find any information specifically about high temperature pumps. When I contacted Daiken about previous problems with the installation they weren't very helpful. They more-or-less said that it was the installer's job to sort them out. Jon.

High temperature heat pumps are no different than other heat pumps, it is just they can operate at higher temperatures, but you would only wish to do so if it is absolutely necessary.

What determines the temperature at which a heat pump needs to operate is the ratio between heat emitter total output capacity and the calculated heat loss of the building.

The starting point to improve your system is to turn all the TRV's to the highest setting, except for possibly those in bedrooms.

Then set any room thermostats to a setting of 2C above the desired temperature. This ensures that the heat pump is always enabled, but is now being controlled by its own controller.

Below I have attached a Youtube video that details how to set the weather compensation on the controller, but as it states, this can be quite a lengthy process to fully optimise your system. Please feel free to as any further questions.

@lucia Good morning Lucia. Thank you for your reply. I've now looked at the Grand Designs article and the YouTube video. The article seems to confirm that a compensation curve is needed with the Daikin heat pump. The Heat Geek video is interesting but a bit above my head unless I do more homework. There is no separate controller on my system, so everything is set via the panel on the internal unit.

I do have the installation manuals. I found them on top of the internal unit after the plumber who did the faulty installation disappeared after causing a flood and said that he was going to fetch a longer drill. He was never seen again! They may have information about setting a curve, but they are not written for a housholder like me.

I finally got the MCS installation certificate needed to claim the grant a couple of weeks ago, over a year after the system was first switched on and after getting the mobile number of the boss of the company and expressing my views to him robustly about how shambolic they are. I think that I should also have a commissioning code so that I can register the unit with Daikin, and I will tackle that when I have the mental energy to do so.

Unfortunately, I'm not on Facebook and don't want to join, but I have a friend who is and perhaps he can have a look at the groups for me.

@derek-m Good morning Derek. Thank you for your reply. The YouTube video is much clearer than some others that I have watched, although it does seem to be quite a complicated process to do the fine tuning. There is no separate controller on my system, but it looks as though the curve can be set on the panel on the inside unit. It looks as though my radiators were sized for a flow temperature of 60 degrees, but this didn't take into account improvements to insulation and draughtproofing. Once the weather gets colder it looks as though I will have to fine-tune the system as you suggest to get it running efficiently.

@joninorkney Hi, here's the installation manual for your heat pump  [PDF]  it has a section explaining 'weather dependent curves' and low flow temperatures - I hope it helps. Oh... You have this already my bad. 🤦🏻‍♀️

I understand from others that it takes tweaking and trialling in small increments. The usual advice is to keep a record of settings before changing them so it is easier to revert or map your moves. 

Heat pumps bring a whole new language and way of thinking - For me it has been a case of the more I read the more I will gradually absorb and understand. I'm very much at the beginning of this but one good thing is that people here are really helpful. 

If you have specific questions you could get your friend to ask in either the Daikin support Facebook or even the Octopus heat pump group - you can find lots on setting curves, flow temps etc., 

@lucia Hello again Lucia. Thanks, that looks useful. The heating season hasn't begun properly yet, so I will probably wait for a few weeks before I seriously start to try to tune the system.

@joninorkney I'll reach out to Daikin tomorrow (Monday) and see if they can help you remotely, and it would be great if you could provide here to see what their customer support is like and whether/how they were able to help you.

@editor Hello Mars. That would be good. I did contact Daikin last year about some problems with the installation and they simply referred me back to the installer. To be fair, when the experienced plumber returned from sick leave he spent a week re-doing the installation. There were some pretty serious problems that he corrected, including the outside unit not being level, the expansion vessel not being upright, pipework not being routed properly, no insulation, a blow-off pipe discharging into a floor void instead of to outside, a radiator being under-sized, and so on. It still cut out 4 or 5 times a day, and at the end of May this year, over a year after work started, he spent another 2 days here. The first day he drained and bled the system and fiddled around with various things. The second day he looked at the installation manual again and removed a circulation pump in the cupboard under the stairs, which apparently isn't needed and had been fighting against the pump in the internal unit and causing a water flow error. So perhaps you can see why I am skeptical about his advice on controls and curves!

Posted by: @joninorkney

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still cut out 4 or 5 times a day

What do you mean by cut out. Are you saying the fan stopped (if so that is normal) or just stopped working and the tripped the main breaker? Or something different?