@cheshirejohn Welcome to the forums and please feel free to ask any questions.  Lots of people here are willing to help.

Can I suggest you read the ABC guide here, it will help you understand the basics of heat pumps and the key differences between heat pumps and boilers.

You say your house is a new build.  Can you tell us about floor area and types of emitter (rad, UFH?)), also a post picture of the buffer tank.   7700kWh is rather large for a new build unless its a large house (say >250sq m), so there is probably scope for improvement in efficiency.  You are right also to seek an appropriate tarrif. 

Start by forgetting everything you may have learned about controlling boilers, heat pumps need to be 'low and slow' and pretty much on 24*7 for minimum running cost (and maximum comfort).  Operating them is, in essence, very simple.  Set any (or at least most) TRVs and all thermostats to well above the desired temperature, and any heating timers etc so they are permanently on.  Then adjust the weather compensation curve down until the house is just warm enough.  Leave.  You may have to wait until next season to tweak the adjustments though.

What do you know about how its currently adjusted/being run.  Do you have timers/TRVs, do you know if weather compensation is enabled and if so what the parameters are.  If you dont know any of these dont worry, if you read the abc guid it will start to make more sense.

If you reply before Nibe come round we may be able to give you some useful questions to ask.

Posted by: @cheshirejohn

↑

the installers don't want to know despite repeated phone calls and emails to come and service the system and explain its workings to me

That is is statutory requirement of the Building Regulations, Part-L.

For any work that falls within their MCS Accreditation (solar panels, battery storage, heat-pumps etc) they must:

• Create a check list of what needs testing, and sign off each line
• Commission the system to use as little energy as possible (not just test that it runs and then leave!)
• Provide you with Site-specific documentation, describing what they've actually installed and where the various valves are
• Explain the operation of the system so that you are able to operate and maintain it

If the Installers haven't complied with Part-L, then have they even sent a Building Regs Notification to your Local Planning Authority (LPA)?

Posted by: @transparent

↑

That is is statutory requirement of the Building Regulations, Part-L.

 

OP said that its a new build, so I imagine this requirement falls to the developers not their subbies, or (possibly) is discharged because the developers possessed it for a while before selling it on.

Good point @jamespa

But that probably strengthens @cheshirejohn 's case

If the heating system formed part of the main build, then there will be a Building Control organisation responsible for signing it off.
That means there's a contract in place for the survey work.

So the Local Planning Authority would be able to threaten Enforcement Action if it's been signed off whilst not fulfilling the requirements.

@jamespa 

Thanks for your replies

The size of the house is 210 sqm with underfloor heating down stairs and radiators/ heated towel rails upstairs. All the radiators and towel rails have TRVs on them

Downstairs each room has Heatmiser Neo stat V2  thermostats and there appears to be time clocks for the heating and possibly hot water which also appears to have a back up immersion heater unit

With regard to if there is temperature compensation and what this is set to i am waiting for NIBE to explain those finer aspects tomorrow when it is serviced

I have the instruction manuals for all the components but none of the initial checks and commissioning checks seem to have been completed  or filled in the instruction manuals so this is another thing that will need to be looked into also no paperwork regarding the design or spec of the system

I have inserted a photo of the system with the hot water cylinder on the right and the 100 ltr NIBE buffer tank on the left.

I can recommend the two books Bodge Buster and Zero to Heat Pump Hero as a very good guide to learning about Heat Pumps

Servicing by NIBE in the morning so i will see what that reveals

@cheshirejohn thanks for the update and for sharing. I’m really looking forward to see what the NIBE engineer has to say.

3 weeks later and two visits from the NIBE engineer to service the system 

First visit and he found that the controller was not working properly and the screen was not functioning so no information could be gained about the system and a new controller panel was ordered

This week a new controller panel was fitted and the NIBE engineer who was very pleasant and efficient completely set-up/reset the system and serviced it finding that one of the inline filters was clogged with large amount of "Plumbers Paste" and the sensors were not in the correct place. There are also problems with the plumbing in that the hot water cylinder is not the last connection on the return to the heat pump so i need to get the installer to sort that one out. 

5 days post servicing and electricty consumption has dropped  very markedly and i feel we are making good progress in getting the system sorted out.

The NIBE engineer has explained everything very thoroughly and demonstrated how to fine tune the settings etc so feeling more confident with it now. The main problem has been booking visits with the NIBE office, their office can be very challenging to deal with both by phone and by email and if you phone and end up going through to  a call centre they have at Head Office in Sweden it can be extremely difficult but i gather they are aware of this.

Glad to hear that things are moving forward.  The photo you mentioned didnt load unfortunately

12kW in a 210sq m new build is way oversized (by probably a factor of 2) and with all those external controls and a buffer tank its very likely to cost a lot more to run than it needs to, unless you tune it up and arrange it so most of the external controls aren't doing anything.  You wont see this much now because its warmed up, but unless its optimised costs may well go up a lot once it gets cold again later in the year.

Its now a bit late in the season easily to set it up properly.  You should be able to do a rough and ready job that's good enough for now then tweak when it gets colder again - perhaps October/November.  In summary I recommend to set most of the external controls so they have no effect, get the WC curve as low as possible consistent with heating your house, and balance the buffer tank to the extent possible.  I will provide more detail if you want to do this or maybe it has already been done/its good enough for now and you can wait until winter.  Has Nibe finished?

One question about construction, is there a big concrete slab downstairs that forms the floor and can be used as a heat store.  With a well oversized heat pump you may want to 'batch heat' on cheap leccy, at least in the shoulder season.