JohnMo

I would always go back to the EPC author and get them to correct any mistakes, because once you get in to the nitty gritty they tend to be rubbish in rubbish out, full of assumptions, from a 10 minute walk around, if your lucky.

There are double glazing solutions that are suitable for historic, listed and conservation areas, if you look. In most cases can be fitted to an existing frame.

Put an electric heater upstairs on the landing with the bedroom doors slightly open on the coldest days. Get one with a timer and thermostat, that should back fill the heating on the coldest days.

You do if classified as a self build, you get the full grant.

Perhaps a drawing may be neededcof your roof buildup? So we all know what the issue is you are trying to get around. Mine are on directly attached to sarking boards with a membrane above, so zero membrane droop, and then the GSE panels. Been in operation for a couple of years no issues. But if you are having tiles and not slates you will be having battens across the roof anyway, so would have a ventilation anyway below the PV and tiles. The GSE panel and PV will not be changing that. But a drawing needed really.

Think you may be over thinking. The heat pump is just an electric user, it doesn't care where electric comes from. You can keep this Uber simple, 3 port valve to UFH and UVC. If you want to generate and power the full house in a power cut, you only have a couple of options, Tesla Powerwall or Givenergy All in One. Both can fully integrate the generators, grid and car charging. Unless the wind turbine is big, it likely to be piss poor performance.

Basically you will have a quick recovery cylinder. No issue driving a heat pump coil from a gas boiler. I found "Ideal" cylinders from City Plumbing to be very well priced. Come with a 28mm 3 port diverter valve and all the safety bits. I would upgrade to a digital dual thermostat, for about £20. Thing to concider If you are running out of water with a gas boiler, you don't stand much hope with a heat pump, with lower storage temperatures.

Are you just trying to do things too quickly? Low and slow compared to quick and high. 45 degree flow temp to UFH, says you are trying to heat it up quickly. The result is the heat pump is too small to keep up. Run everything at a lowered temp for longer is likely to fix this.

I would buy a garden room something like 70mm log building. Some insulation in the roof and floor. Only requires a simple foundation. Everything required in a single package.

I would question how are you going to get different temperatures to the different areas and a very different heat required for the FCUs and UFH, or are you planning to run at same temperature?

The good thing if you do change the mixer for an Ivar, there are plenty of adjustments and fine tuning you can do. You can actually reduce the dT down quite a bit, think I managed to get the dT down to 5 degs across the valve. The mixer may be gummed or scaled up restricting internal parts moving and you are getting under and overshoot or generally worn. I moved to an ASHP and as I only have UFH eliminated the the pump and mixer all together.

I'm in the same boat, no MCS installs, my build started with 3.1kW of DIY solar have since added another 3.6kW of DIY solar and a self installed ASHP. No grants or long loans bothered with. All in about £9k. Have also added a battery, so no export anyway. During summer, once battery charged, ASHP will be on cooling duty.

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I have an Atag boiler, they are quite impressive. They are advertised as opentherm, but like a lot of companies they are not fully opentherm, you may need to use one of their controllers to get all the features.

Do you have the something to read the earth potential (think that's what they call it). You after 200 Ohms reading or lower between it and the live and neutral. My spike went down 8 or 9m to get the reading correct.

Mine looks like it goes into the changeover switch, and seems to the joined to the existing earth. So I suppose the earth route can be the original, the new and or both.

I just used some decent pair of industrial scissors. Best purchase ever, used them on loads of stuff on the build.

I think if manufacturers weren't constrained by costs things could be different. For example my ASHP is the same external casing for a 4, 6, and 8kW units. Will be a lot of part sharing going on, instead of dedicated parts for the large and small unit. My unit isn't small, but it's no where near the size you are referring to, the 14 to 16kW versions are that size, but 4 to 8kW are 828mm tall and 924mm wide. The 4 to 8kW being more typical of the size being installed. Pretty sure the 4kW, in a dedicated casing could be made a lot smaller, even as a monobloc.

Cannot see why that would not work, also if you use the refrigerant to heat the cylinder, (divert it before the plate exchanger) that is around 80 degs. Cascade control schemes are nothing new, my ASHP is already pre-programmed for it.

So agile has two export tariffs, an agile type and a fixed cost type.

Is import or export? For export you can be agile export or fixed price. Import if you have a battery would be direct to battery, they wouldn't know or care about it. Even without a battery you would be self consuming or exporting

He could, but not sure it would change or stop short cycling when only running UFH. He needs water capacity, to dump heat into, which is what's missing.

Mines been in use for a couple of years, no issues - except to top up the air once a year, when the filter package is being serviced. Mine is outside in an insulated shed.

Just looked at my boiler pump (32kW) and it max head is half and flow at max head is half the one installed.

We have a borehole and have the very thing upstream of the filter system. Couldn't agree more