ProDave

Okay I see you wanting perfection in speaker placement, but I would be looking at room layout to achieve that with the speakers looking a bit more like they belonged. Can you overlay the speaker layout over the room layout so it makes more sense with the window position? I would reserve this setup for a windowless (or window behind listener) cinema room. We have mere old fashioned 5.1 sound in our two main rooms.

A picture of the white control box just out of shot above the first picture? Make sure all thermostats are off except for the upstairs one when you take the picture. Picture 1 shows no flow so I assume everything is off. To make any diagnosis the pictures need to be take in "fault" mode, i.e. flow when there should not be.

What is the reason for what looks like really odd placement, one just left of the window, one in the middle. What's the full picture of what you want to achieve? If you ever move, the next owner will not thank you for a hole in the window cill with a bit of wire poking out.

Post some pictures of you rmanifold and any valves or pumps near it please?

So when you are in the state of the "heating has gone cold" is the outside unit still turning on and off, or does it stay off?

What would make sense to me, is every business premises installing solar PV on it's roof. They are working in the daytime (mostly) so ideally placed to self use all that they can generate. If the rules on how much you can export were more flexible (i.e. take self usage into account rather than the silly rule that assumes all you generate will be exported) then they could fill their entire roof with PV.

Is the circulating pump next to the two big yellow and red switches making a gentle hum or is it cold and silent? Lower down there is a silver box about 80mm square into which the cable from the mixing valve goes (amongst many others) Two SWA cables emerge at the bottom and I bet they go to the outside unit. If he has (probably inadvertently) messed up the wiring in that box, the ASHP may not be getting a call for heat from the heating.

Yes the unit in the garden or the big silver box in the bottom of the cupboard, are either of them making any noise? What about the circulating pump in that cupboard? is that making any noise? You should usually hear a gentle hum of you put your ear close?

So does the ASHP continue to actually run when heating is demanded? I am now wondering of that change of mixing valve has messed up some of the wiring and the ASHP is no longet getting a "call for heat" when the heating is on.

Going back you your blending valve, I assume it is this one you are talking about? The bottom pipe is the heating flow into the mixing valve. Is that remaining warm? (if it's in the region of 45 degrees it should feel hot to the touch) or is that pipe cooling down (if it's only 20 degrees it will feel cool or at best barely tepid to the touch)

I looked at those and found this So for 1 panel and 1 micro inverter that adds a lot of extra cost. It is not clear if you could just use one of those microinverters without the Envoy device but I bet even if it worked, that's your 25 year warranty down the pan. I was looking for a decent equivalent to the Chinesium micro inverter. DC in one end, grid tied ac out the other, nothing else needed. Just need to find a reliable version of that next time my Chinesium one lets some of it's smoke out.

Because at the time I could not find a "proper" inverter that would work with just one 30V panel. Please enlighten me.

They will no doubt help, but as you say probably there for the extra couple of SAP points needed to scrape a building regs pass. I would be interested to see what small inverters they use. I guess they don't care if they fit one of the cheap Chinese mini inverters and it goes pop after a year. The home owner would probably not even notice, especially if it was hidden away in the loft.

Does your council have a written policy stating how much area a garden needs to be? I see lots of houses on infil plots in our local town that have what strike me as absolutely tiny gardens, but they got planning, so obviously the required space here is pretty small. Somewhere to store your bins, a clothes drying area and somewhere for a bike rack or bike shed seems to be all you need here.

These are Exhaust Air Heat Pumps. they work as part of a whole house ventilation system and extract heat from the exhausted air. I don't think this will heat a whole house. I have heard lots of things about corrosion in some makes and know of one that was fitted to a new house being removed when not very old and replaced by a normal ASHP with an outside unit.

A single PV panel is probably not viable for domestic use. The problem with just one panel is the DC voltage is low. Most of the "proper" solar PV inverters are made to work with a string of panels in series and a higher input voltage, probably a minimum of 4 panels. You can get a single panel to work, I have done that in an odd situation mainly to use up 2 "spare" panels, but the only inverter I could find is one of those horribly cheap "no name" Chinese inverters on ebay, except they are not as cheap now, I bought mine for £50 but they are now more like £75. But they are not reliable, I have repaired mine once at not much more than 1 year old. I am not sure what I will do if it goes again and I cannot repair it, I am not minded to buy the same one again, but don't know of a respected make that would do the job.

Even a normal sized 4kW solar PV array would not produce enough power in the winter to run the ASHP. It is simply impossible to power an ASHP entirely from solar PV. Instead regard solar PV as a way to reduce (not eliminate) what you need to import from the grid and it does this all year even when you are not using heating.

An alternative suggestion is smaller pipes on the long run, accept it will kill the flow rate and might upset the ASHP and counter that by adding an extra circulation pump at the house end to help push the water at an acceptable rate.

WOW just WOW you spent £1000 on a "repair" and it's still not working. I would get them back and not let them leave until it was working properly. All at NO extra charge, just getting them to make what they fitted work properly. I sometimes wonder how people have the balls to charge outrageous prices and have no shame or concern if the work they have done works or not. I am pretty sure if I took that attitude it would not be long before I had no work and people were advising others not to employ me.

First question: Is the ASHP getting hot enough to heat your hot water? If it is, the fault is nothing to do with the heat pump and it's recent service. Post a picture of your under floor heating manifold and any gauges it has on or near it.

What is the reason for wanting it so far from the house?

That will limit your choice of furniture etc. If anyone is thinking of bidding, CHECK that it has services connected, at least water, drainage and power. If not, and that "tunnel" is your only access, best of luck getting it serviced via that route. The guide price does sound cheap for the area but even if you can complete it, with the tunnel access, and no view it is not my idea of a dream home. That must have taken some work to "create" that plot. I reckon it's a good chunk of 4 back gardens, and a sliver off 2 more, plus the access through the tunnel.

So the feed to the caravan and the site socket(s) are separate. The important thing (your electrician should know this) is you may need a local earth for both of them, the general rule is if you have a TNCS earth then you do not connect that to either. So in your meter box a mini consumer unit to feed the caravan and site sockets from their own MCB's. Site socket needs an RCD, feed to caravan may be without an RCD if the caravan has it's own CU that contains an rcd. 16A socket is more normal for a site socket. Normally for a static caravan you take the feed straight into the consumer unit in the 'van, not normally via a flex and a plug.

Static caravan or touring caravan?

That is more than just a simple PRV. Cold raw mains in one side. Pressure reduced out to the HW cylinder the other. The 22mm from the bottom is cold pressure reduced water out to feed the cold taps so they match the pressure of the hot, and the 15mm is the vent from an over pressure relief valve to a drain via a tundish.