JohnMo

What's not shown is the DPM, DPC, this needs to be shown. I would be tempted to have a 50mm service void then plasterboard and dry line. Overall there doesn't appear to be much insulation in the wall or the floor. If you are going UFH heating your floor really needs a u value of 0.1 or better, in my option, otherwise a lot of the heat will travel downwards. Not really seeing a thermal bridge with option 2, as you have continuity of insulation from the internal wall and around the underfloor areas.

We used 48mm battens and used slim led down lights of various diameters. All sit below airtight vapour control layer. So no issues with air tightness, drafts and no cutting the vcl. We used an aluminium foil acvl from Passive House systems, not the cheapest, but nice to work with, it drapes down the walls and is stuck to the wall with a special mastic they sell for the product. Joints are taped with aluminium tape.

This could be an option. Alpha boilers sell them, may be worth a look. Basically a combi boiler, with preheated water, to up the performance of the combi, so it's doing less work, so can produce a better flow. Combi-SuperFlow-White-Paper-v1-2-4.pdf Canetis-SuperFlow-Product-Sheet-WE-050318.pdf

In a sealed system the pressure within the system gives the suction head. An open vented system, the suction head comes the loft mounted cold tank, so as you say the pump can be mounted anywhere in the system. The suction head required increases with flow and generally in the range of just over 1 to 2m.

All centrifugal pumps require a positive suction head, if they don't have it they cavitate and do not push flow forward.. the 5 or 6m head is the discharge head.

But the pump at the ASHP is pumping around the coil in the cylinder and cannot affect what's happening at the UFH pump manifold. The pump at the manifold is trying to suck hot water from the cylinder and and around the UFH loops, but cannot as the required suction head is not adequate. My system is exactly the same as you're got, with the cylinder 3m above the the UFH manifold, have no issues, as I am giving the pump at manifold the required suction head. So all you need to do is increase the suction head. Either raise the cylinder to increase suction head available at the UFH pump or install pump.

50% less heat loss through the floor. The effect of better insulation with UFH will be greater than without, as the floor temp at the insulation level will be higher. UFH temp at insulation approx 35 deg, with radiators it will be closer to 18 deg.

Bit confused by this thread, the issue is not short cycling of the ASHP, which seems to what everyone is trying to fix. Instead the issue seems to be hot water not being drawn into the pump suction. Nick's drawing would allow the pump in the ASHP to push hot water the the UFH manifold pump, but needs the whole system with anti freeze, £150 mentioned. A small pump would fix issue, without a major replumb, or am I missing something?

I would do all the built in stuff first, then floor covering. Floor covering are replacable, if they are under built in stuff it a pain to change out. The built in wardrobes would normally be in place for ever, so floor covering butts up to them..

If its noisy it could be pump cavitation, due to limited water pressure upstream of pump. It will wear the impeller in the pump quite quickly. To fix either increase elevation of tank upstream or install a pump. Or a small hole in blocked bypass may fix, but would reduce temp at manifold. Tweek temp up at cylinder to compensate. Or small high efficiency CH pump set to min speed, let it run 24/7 during heat season?

You can locate panels East, South and West. Install with optimisers, will keep performance up with shading.

You don't drill through any slates to install the "solar slate plates", the plate replaces a slate and sized to match the slates you have installed.

I used Wood Kraft in Elgin, they are wood, not Ali clad, but very good quality. I have a some big windows with angles, so wanted the same company to measure and install. No real issues, any issues were solved easily, with the workshop just 3 miles from site. Would recommend them and use again. Not cheap, but worth it.

Various sizes are available, ours are 310W each, so 10 panels, ours are in an approx 10m long line.

Saving are better than before, (pay back quicker) with current and expected cost increases. Plenty of companies sell a kit of parts, a local electrician can install, a PV diverter to immersion. 3kW system should allow you to self consume what you produce.

What about using solar limpets, or solar slate plates, don't see why they make the process more difficult.

No reason

We bought everything in sales, saved a small fortune, not had any issues. Most bought when we were at foundation stage, some before that (pre lockdown sales at start of COVID). But to this you need to know what you want and where it goes - but then don't change, over wise you'll have a lot of stuff that no use to you.

I have used crystal clear and it's very clear, BUT has to be exposed to UV to stay clear. Whatever you get read the data sheet to make sure it stays clear where you plan to use it

Temporary work platform is a triangle of steel with a tongue at the top which is hammered into the sarking board. Two or more pieces attached then a scaffold board.

Slate with GSE - before and after

If you go this route do it on E7 or similar low tarrif

Before you go A2A, have you lived, been in a building where you have A2A wall units? I have and found them noisy, blow drafts at you and are generally annoying. Would not have them in a house again.

Both nod and I posted at same time. As an example I have roof integrated PV 3.1kW and it takes up around 15m2, on a DIY basis cost cost just over £2.5k with electrician cost included. No roof tiles needed under PV. A concrete tile weighs in quite heavy when compared to slate. Have a good look around, to see if there is any sag on the other roofs, IE is the roof line still straight. Also did they have to reinforce the roof, with extra wood etc. Look on gumtree etc for people selling excess Welsh slate, you may see a bargain. Get the roof stripped, the existing slates inspected as they come off and reuse the good and replace the bad. Find a decent slating company, ask around knock on door in the local area etc.

Best guess would be the point where the vent stack goes through the roof. If it is damp now it is a current issue or dry could be old or just not leaking now.