ProDave

You have rung alarm bells there by telling them you are going to have both a GSHP and an ASHP each at 10KVA so they will have been working on providing a 21kVA supply. no wonder they want to upgrade their network.

A site layout plan would help the understanding and and make more informed comment likely. How about a compromise with the doors on the side?

But this mistake did not just arise when the window went in, it happened days or weeks ago as the house shell went up and the window opening was too high. Did nobody notice then?

If you only actually need single phase in the house how about 2 cores for L, 2 cores for N 1 core plus SWA for earth. That should take care of it.

I have a frozen vent pipe at our rental in an inaccessible loft space that has defied any attempts to defrost it. I am awaiting tomorrows "heat wave" to see if it thaws it then see it there is a burst. Don;t underestimate how cold it has been and for how long up here.

I can understand this for a workshop with lathes, mills etc but what in a kitchen or cinema warrants one?

As much as I like ASHP's I would not be suggesting one for this property, particularly as you might be selling in a few years. It's main problem is no or poor insulation anywhere and with it's age and construction it's going to be very hard to get it anywhere half decent in that respect. So your main problem is going to be a high heat demand and large heating bills.

Normally mains water will blow air locks out of the pipe, it's usually only a problem with low pressure heating systems.

In simple terms treat it as any other 16A radial circuit to a 16A "load" Only in this case it does not consume 16A it produces up to 16A. That gives the rather interesting problem that "volt drop" manifests itself as volt rise. So if you have a long circuit with a poor Zs the voltage at the inverter could rise above 253V where most inverters will shut down in some way. So calculate your volt drop in the normal way, and add that to your typical supply voltage and ensure you don't exceed 253V As well as all fusing. rcd's etc for any normal circuit you provide an AC isolator switch next to the inverter and also a DC isolator switch for the PV panels (some inverters have the DC isolator built in) Most 4kW inverters will have the panels as 2 strings so you would need a 4 pole DC isolator, or two separate 2 pole DC isolators. In days gone by for the FIT you would have a generation meter next to the inverter to measure how much you have generated. Without a FIT that is not strictly necessary but still a useful thing to fit.

I thought you were just on about installing solar PV? If the overhead SWA works and is rated properly that would not stop you installing PV on the garage. If you want to change it for other reasons that is a separate issue.

Why do you need to update the house feed to do this?

Table 4E4A 25mm SWA multicore 3 phase, buried in ground or in conduit in ground current carrying capacity 96A It does not quote a derating for being in insulation. Looking at other tables for non armoured cable you typically derate 20 to 30% for being in insulation. To be safe I would want 25mmSWA fed from a 60A fuse Will 60A 3 phase do your needs?

The garage looks best for the PV, easier to fit and you don't have to look at them. I take it you have power to the garage? If not do you know an electrician? A normal 4kWp array just needs a 16A supply connection. It does not matter where they are connected it will all be upstream of your meter, My kit is all in or on sheds.

Can you post a picture of your nearest pole, the next one along, and the wire between them?

What capacity (kW) supply did you ask for? What capacity supply do you NEED? Have they offered you any supply from that pole? We accepted a 12kW supply as that was available without any network upgrades ans was enough for our needs. I would investigate that avenue first.

So it's not a pump issue it should be passive. So I can't think what else it could be other than the cold feed to the tank had frozen.

Does your thermal store work with a heat exchanger and a pump, or is it a passive one that just has a hot water coil through the stored water? But either way, no water coming out of the tap means no cold going in to push it through. It sounds like a frozen pipe to me. I would look very carefully at how the cold in gets to the tank and does it pass any areas that could freeze? We have been down to -16 here, and at this time of year the cold water in is about 3 degrees, it would not take much to freeze that,

Another one here that can confirm a properly positioned stove that is able to circulate air to the whole house, works well in a well insulated house. It is when you design a stove that is shut in one room with nowhere else for the heat to go, that you get overheating problems. Top tip. Get all your firewood split in plenty of time. I need to go out with the snow shovel today just to find my chopping block somewhere under the snow, then clear a path through the snow for the wheelbarrow.

Can you not get the duct under the insulation? The wring regs are not specific on what counts as "insulation" but I would say being in the middle of a sandwich of EPS with a heated slab above it and unheated ground under it, would concern me. Ideally I would want the duct under the bottom layer of EPS. I would certainly go up to 25mm in this case. What are you using the 4th core for?

The "issue" I have with this ASHP having the return as the set point, is it then maintains +5 for the flow temperature. I have observed with mine when only one UFH loop is on, there is very little difference between the flow and return, perhaps 2 degrees or even less. So I would never achieve the 5 degrees it wants and I would end up running with the flow temperature hotter than I want, by which time the return temperature would overshoot it's target. But it is the way the manufacturer has designed it so you have to work with it.

Without some serious re thinking on the wiring there is not much you can do about that. But it might be a handy measure of how much solar PV is going to the immersion heater if you are sure it is not the ASHP turning on the immersion.

Seriously. Get a scaffold tower on wheels for this job.

Yes it's positively "warm" here, only -14 last night and it got up to -4 this afternoon.

For the small extra cost get a dirty water model, if only for the fact they won't want it returned if there is an issue.

The end of my build should coincide with retiring, so time to go and do all the things / visit all the places on the bucket list. and I might get round to trying to make my classic Landrover look a bit nicer.