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You never know if you don't try!

Congrats! I read your blog a while back then lost track, good to see you moving forward!

Does your plot currently have planning? If not, I could imagine the architect having concerns about whether planning is feasible for the plot and asking a specialist about it before taking you on.

More thinking of biological gunk blocking it than corrosion.

Good luck with that! I didn't think plate heat exchangers would last long when exposed to pool type water.

Getting a bit off-topic but what are you using as the heat exchanger between the tub water and the ASHP? Not great, not terrible. Is that with the ASHP plugged into the controls or just the controls?

Looking at your earlier photos, looks like you have a couple of electronic valves down there. Normally make a whirring noise when operated (usually at start/end of a cycle). Given the grinding noise I'm not confident to tell you to try again to try and identify the source of the noise (hopefully others can advise whether it's making things worse to try). But assuming the grinding is coming from a valve then either the engineer removed the head to work on / check the system and didn't refit properly (could be a quick fix) or the valve has failed (strange timing for that given everything else). They can be operated manually which might be enough to get you up an running but wait for someone else with more experience to confirm what to do. My other thought is that if its the CH valve, then its entirely possible that this issue only affects the CH mode and the DHW mode will work. Again wait for others to speak up.

Whats the pressure reading below the red tank?

Understandable with many things but not CIL. If CIL is applicable then it's applicable and as a self builder you need to take action before construction starts to get your exemption. This forum unfortunately has multiple cases of people not taking action early enough and getting caught with huge bills. Confirm with the council before you start anything, getting this wrong could be the biggest unplanned cost in your project.

From the horses mouth: https://www.gov.uk/government/news/record-breaking-auction-for-offshore-wind-secured-to-take-back-control-of-britains-energy It's more like £140 (gas) and £91 (new commitment) according to their figures. Surprised me as both seem very high compared to the numbers that I'm used to thinking about. Later in the doc they say the prices are often stated adjusted to 2012 prices and in that regard the wind is £65 which sounds much more in line with what I was thinking.

Also, assuming you have an 8kw ASHP, it's unlikely to draw any more than 3kw outside some unusual scenarios (assuming a well designed system). Normal operation should be much less than that. Electricity in should be less than 1/4 heat out (COP 4+) except during hot water cycle. So it's easier to generate what you need on the relevant phase. Assuming you have 3phase solar then the ASHP will be on one of the phases.

I thought the air sealing externally was for hot climates where you ran AC inside and want to stop the moisture getting in. With our climate we generally want to seal from the inside out. Still might be useful concepts here though. Edit: Matt is based in Texas

AFAIK Accoya is thermally modified Pine. So not a hardwood, but the modification process means it should be very resistant to the elements and should outlast almost all wood species.

I laughed but then felt a pang of guilt that @Pocster is always at the arse end of jokes. I'm not even sure I get the joke as I've read a lot of the threads on here and don't feel I've read about what must be a hell of a story. 🙃

I think there are two problems. 1. The pressure loss from the ASHP water system 2. The leaking tundish from the potable water side of the system I'm not sure if we have seen enough info yet to be sure.

If this is related to using the immersion then don't. Using the immersion is worse than using the ASHP to heat the water at this point.

Indeed and that's the bigger problem, though not directly (I think) linked to the pressure loss in the hot water system. Overpressure issues triggering safety systems much more urgent than loss of pressure. I would guess so but listen to the experts here not me.

Don't think I've seen anyone else mention this yet so I will. A small leak like this is all thats needed to drop the pressure in the system. I'm guessing this pipe is part of the DHW heating loop though wider photos would confirm. Unless I'm mistaken, until that dampness is solved I'm not sure it's worth looking for other issues.

Not talking a pro one. Lidl were selling them last year for not much (though duty cycle of these things means you'd need to take regular breaks for it to cool down). Similar can be found on ebay. Should be a load faster and quieter doing that than chop saw. Pretty sure you could find an angle.

Probably crazy, but what would it cost to crane it out? Investing time and money into a 6 month temporary solution is gonna add up. If it has to go then this might be cheapest. It'll get recycled anyway so not too much of a waste. Might be worth investing in a new toy (plasma cutter) rather than a chop saw though.

Welcome! Overall looks like a nice plan. I am curious what's driving decision to dedicate so much of the space to the master dressing room? I would have thought a smaller dresser and a 3rd bed/office would be a better use of space (and more saleable if circumstances change). Alternatively, a layout that allowed some of the dresser to be made into that extra room without significant rework. I assume you wouldn't have got this far into the design without serious thought into this so really curious to hear your thought process.

ASHP + water fancoils can do the same as ASHP + refridgerant fancoils. ASHP + UFH cooling can't. ASHP + water fancoils has the benefit that it can also do DHW heating but will, I believe, be marginally less efficient than a refridgerant system*. Most large offices and industrial sites will use water systems as refridgerant is expensive and hugely environmentally damaging if it leaks so it doesn't make sense in big buildings but is cheaper in small scale installations. It is incorrect though more in understanding the context of when it's been said. I think you've mainly seen it said here in relation to systems that either don't want to go below dew point (to save extra effort in insulating all the pipes thoroughly) or because the system fed under floor systems that indeed can't compete with fancoils. * Because of the restrictions on use of R290, it's possible (purely guessing) that a water based R290 system may well outperform an older R410 refridgerant system. Probably not a modern R32 system though.

Clearly it's not for you, but just in case other people are looking, you can make wiser be dumb as a brick scheduler and thats all. It also lacks some of the more advanced smart features of others.

Though having read the OP now, Wiser doesn't seem right. All the thermostats, etc, are wireless (though not wifi). What I said was in relation to the main controller that sits next to the boiler. Not sure it would be a good idea with ASHP either.

Wiser works without the internet connection after being initially set up. I believe it's also possible to completely configure it through the Home Assistant add-on without using the Wiser app (going through the registration process) at all, though wouldn't recommend that. It was good this xmas to be able to turn the heating back on at home in advance of getting back after being away a few days.