@cathyem1 - welcome to the forum.

Posted by: @cathyem1

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My supplier should be coming to see me to go over the workings of it next week.

It might be sensible to wait until after this visit - the supplier could just as well get things right or wrong! However, in preparation for the visit, it won't do any harm to mention some basics.

1. You do not want to use a room thermostat to control the heat pump (yes, the subcontractor got that wrong). You want the heat pump to be always on, which means setting the room stat very high - say 28 degrees all the time.

2. The control comes from something called weather compensation. Basically this controls the temperature of the water leaving the heat pump according to the outside air temperature. When it's cold outside, you need more heat, so the LWT (leaving water temperature) goes up, when it's milder you need less heat, and the LWT goes down.

3. You then aim to get the weather compensation settings such that they are at the lowest LWT consistent with keeping your home warm. This is a trial and error process: you start with some initial best guess settings, and watch happens. Home too cool? Up the weather compensation settings a bit, and see what happens. Home too warm? Lower the weather compensation settings a bit, and see what happens. Carry on until you get it just right.

4. The ease of setting the weather compensation settings varies with heat pump brand. If you have a manual (or can find one online) it should tell you how to adjust the settings. Your supplier when he visits should also be able to show you how to set them. Normally there are two pairs of settings, one for low outside air temperatures eg 45 @ -2 which means LWT at 45 degrees when it's -2 degrees outside, and one for high outside air temperatures eg 30 @  15 degrees which means LWT at 30 degrees when it is 15 degrees outside. In between these outside air temperatures, the weather compensation operates on a sliding scale between the lower and upper outside air temperature end points.

5. You also want to mostly run the system as 'open circuit' as possible. What this means is no obstructions, specifically no TRVs (to start with, occasional bedroom use may be OK once you have the system set up).

That may all seem rather daunting if you are new to heat pumps, but it basically the bread and butter of how we run them. Always on, low and slow, with control coming from weather compensation.

Good luck, and let us know how you get on!  

That's the sort of schedule we'd expect to see for a typical gas boiler installation @cathyem1
but it doesn't best reflect how your heat pump should operate.

It is a requirement of the Building Regulations (Part-L) that you are supplied with site-specific documentation,
and instruction on how to operate the system such that the (electricity) fuel being used is minimised.
Ie, that's the definition of an efficient heating system.

Simply handing you the manufacturers' instructions for the heat-pump, thermostat, and domestic hot water (DHW) cylinder is inadequate to comply with Part-L.

You should have the system diagram for your particular house, and the Commissioning Procedure sheet, with the results for each of the 'tests'.
That will include the settings which the contractor arrived at to optimise the system.

You should have already received the Household Energy Survey report, which was completed prior to installation.

That gives you the design parameters which were used to dictate which specific hardware was required for your home.

It will show the total energy losses for the entire house, which are used to decide the size of heat-pump required (in kilowatts),
and the losses for each room, which dictates the size of radiator required, and the size of pipework to deliver that heat.

Can you also please tell us the model of Baxi which has been fitted?

and basic description of your house

• when it was built
• detached/terraced etc
• number of floors
• number of bedrooms
• floor area in square meters (or any other units, and we'll do the calculations for you!)
• what insulation is in the attic/roof, and the walls

Looking forward to helping you get this sorted.  🙂 

@transparent Thank you. We did receive a lot of information from the supplier after he did our survey with all the recommended specifications for the new system.

I have been told today, after emailing and texting the supplier about my issues with the system, that their “process” is to send out a handover pack which will include the warranties, certificates and manuals in due course. They will come to see us and talk through the system sometime next week. I wasn't aware of this when the subcontractors left yesterday.

As an aside, I also have solar thermal water heating which was fitted a few years ago, so our cylinder is dual coil.

House is a semi that was built in 2005

2 floors and 2 bedrooms

Floor space is 71 m2

The loft has 200mm of fibreglass insulation that was in when we bought the house new in 2007.

The walls have insulation built in.

The heat loss is noted as 2.74kw on the heat loss report and system design.

The heat pump is a Baxi HP40 Heat Pump air/water “inverter” and the cylinder is a Cyclone 180l dual coil.

That's interesting @cathyem1

Many installers don't like reconnecting an existing solar-thermal  to a newly installed heat-pump system.

It can be more tricky to commission.
The Baxi controller needs to 'understand' that the energy being supplied from the solar-thermal coil might be greater than its own flow (output).

But let's note that it's only feeding into the Domestic Hot Water tank.
There's no solar-thermal gain supplying the radiator 'space'-heating element of your installation, which accounts for 80% of your heat requirement.

@transparent Thank you, yes, I realise that the solar is only helping the hot water and not the heating.

I really hope the supplier comes to see me on Monday as my bill is rising and rising and i don’t know what to do about that other than turn the thermostat own or switch the system off 😬

I suspect that the heat-pump is 'cycling'.

Ie it's switching on/off every few minutes in response to temperature sensors.

If you have Thermostatic Radiator Valves (TRVs) then these need to be fully open.
They're not required for heat-pumps and shouldn't be fitted.
Radiators should be 'balanced' by the installer, using the lockshield valve on the other end.

Only then might you achieve any 'success' by reducing the 21°C setting on the main controller.

Do have any other large 'tank' installed?

It might be called a volumiser or a buffer.

@transparent I have controls at the end of each radiator but they just look like my old radiator valves. They are all fully open. 

I have several other tanks. One in the loft and two in the airing cupboard. See the attached photos,

@cathyem1 - do you happen to know if Baxi is a Midea clone? The reason I ask is the first photo of your wired controller looks very like a Midea controller. If it is a Midea clone, there is a lot more known about them than Baxi. 

From the controller I can see the OAT (outside air temperature) is 5 degrees and also rather interestingly you may be in a time warp (2016)!  

@cathoderay Haha! Yes, the current date needs to be input.

I don't know about Midea I’m afraid. 

What sort of temperature should my system be showing overnight?

Posted by: @cathyem1

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What sort of temperature should my system be showing overnight?

There are lots of temperatures! The key space heating ones are outside air temperature (as seen on the display, by the house icon), leaving water temperature (temperature of the water as it leaves the heat pump) and returning water temperature (some thing for return). These can be viewed on a Midea controller and very likely clones (I am pretty sure it is a Midea clone from the appearance). The display can be confusing at times to say the least, especially the space heating panel on the left hand side. Try unlocking the keypad (long press on the padlock symbol, padlock top left of display should disappear then press Menu repeatedly to see if you can find OPERATIONAL PARAMETER, if you can, select it and go to page 3 of the operational parameters and if possible take a photo of it and then also take a photo of page 4 of the operational parameters and post them here.