ProDave

50C seems hot for heating temperature? does it really need to be that hot? DHW flow temperature may not be such an issue. If you monitor the flow and return temperatures as it heats the tank, you will probably find the return temperature is about the same as the tank temperature at that time, and the flow temperature is a few degrees higher. As the tank warms up, both steadily increase. It is physically impossible for the HP to run at much higher flow temperature as it's only a low power heater. The setting on mime is maximum flow temperature, a maximum cap on how hot you let it get.

The flow temperature (known as water leaving temperature on my ASHP) will need to be about 5 degrees hotter than the target tank temperature, so if your target is 51 degrees the flow temperature will need to be at least 56 degrees. Most ASHP's won't give you a direct reading, of COP. It is easy to measure energy in, but very much harder to measure energy out. So I would not trust the readings yours gives you to be completely accurate.

I have no regrets getting a cheap ebay electric roller door. It fits on the inside and there is no reduction in the opening area.

This is yet again where the Scottish system is better. You would not get a building warrant until all details like that are agreed, and then you know if you build what has been agreed on the plans, there should be no nasty surprises. Do English building regs not check the drawings properly before saying go ahead?

Do what we did, come out level with the house more than you need to to make a nice big level entrance. Then slope the path down from that level platform. The reason for the bigger than need be level platform is it then puts the path a bit further from the house wall so your idea of sloped grassy sides will work.

In @ToughButterCup case could you not run the pipe underground horizontally with a slight fall and vent it out further down the slope, that would let the heavier than air gas out.

If you have windows open in summer you could turn it off. But ours runs all the time. A good test of an air tight house, is you can open one door or one window on a windy day and you won't get a draught coming in our out.

Isn't it to vent radon gas so should it not be open? Where does it actually go? What happens if it is so open rainwater gets in?

And a sketch of a section through the ground, and foundations to see how the 45 degrees from the foundations compares to the excavated ex retaining wall.

And who do you think this governing body that is going to go snooping is? Assuming the panels are on the roof or elsewhere it is probably only an electrician. Start with an EICR limited in scope if you want just to the solar PV. Commercial or domestic client?

In Scotland, you can use a certificate of temporary habitation as your "proof of completion" for your VAT claim. If you do that before you have your actual completion certificate then there is no reason why the rest of the work done as supply and fit cannot be zero rated, right up to the very last piece of work the day before completion. Why would you even tell your builder that you have submitted your VAT claim for the materials that you bought? It is none of his business.

It depends. One job I worked on the window was 1" too high so BC made them install a 1" high step. I am sure the step is no longer there, and if there was a fire, most people would cope with a window being 1" too high without a step.

I would advise caution doing the actual build. Your house is built on sloping ground but nobody knows yet how the foundations were built and how deep. To do your new lower ground floor extension, you need to dig down right adjacent to the back wall of the house about 10 feet. That slab of concrete needs to come up and someone needs to carefully did and see what foundations the house is on at the moment. This must be a real candidate for not knowing the costs of the ground works before you start. If the house is not on very deep foundations then you are into deepening the foundations and it is really like adding a basement to the existing house. Accepting the technical and possibly cost challenges, it sounds an interesting project.

Yes just sour grapes from MCS as they can see their cartel collapsing and losing it's previously protected status as a monopoly. As above, anyone can connect a PV system to the grid, so it is not a "safety" issue. It is pure politics that until now you could only get paid for export if you pay the monopoly lots of money.

How will you seal the joint between the PB and the floor for instance? What about avoiding making a "plasterboard tent" open to cold air from the loft? What level of air tightness are you hoping to achieve? Passive house? Just scrape through building regs? To me the "normal" is a proper air tight layer e,g, a membrane properly taped.

I put 4 CAT6 to the main tv points. Not because I wanted that many, but quite often when some new AV connector comes out (something some day will supersede hdmi) someone makes an adaptor that will convey that new signal type over a couple of CAT6 cables.

No

I did it in mine, easier if the pipes are there before the stud wall.

Optical illusion or is that a very low door built for sports cars only?

Make your back board (MDF, Ply, OSB etc) a little larger so in the example above it goes all the way left to the corner of the room, a bit further right behind the feed pipes and all the way down to the floor. then it is simple to plasterboard and skim around it. Set the back board flush to the wall so you are plastering up to it, NOT behind it.

What i found made the job of a vaulted ceiling MUCH easier, is screw a temporary batten to the wall with JUST enough gap to slot the bottom edge of the PB in than that's the bottom edge secured. You only then have to hold the top edge while you get a couple of screws in. For a long (as in >1 board from eaves to ridge) screw another temporary batten over the top edge of the bottom board to similarly slot the bottom edge of the next board in. Start with full size boards, if you must cut, cut them from that, but persevere to get full boards up. 9mm boards won't be any cheaper than 12.5mm and you may have to order them.

It has not let us down yet and we have a WBS as backup

Check that is the correct fitting for the pipe not just an ordinary compression fitting, and check he has put an insert in both pipes before tightening it up.

Please sir, can I mention we often see -10 for a week or more in winter. Granted I am not your average UK location.

Like I say, these non conformances with current regs are only supposed to be a C3. Any electrician that tries to say otherwise is simply wrong. Thanks to @andyscotland for the link confirming it. I have that guidance note but could not remember where I downloaded it from. Agreed on the singles to the bell transformer but that is such a trivial matter I would just replace it with a bit of t&e without even mentioning it. If the electrician you spoke to says it will need a new CU even before he has looked at it, try a different electrician. Going forward, the issues you might face with that CU is it is long since obsolete, so if there were a problem, say that RCD does not work, your only hope of a replacement that would fit that board would be second hand. You can get rcbo's for those boards, but again hard to find and expensive I have one in my spares box.