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Thought that was recommended against these days. In any case, best to keep the active electronics outside of the hot (in summer) loft if you can.

My worry would be it's 2.5mm2 copper coated aluminium. Still probably better than the 1.25mm2 copper ones mentioned earlier, but nowhere near 2.5mm2 copper.

That one makes my spidey senses tingle. As in is it a dodgy Chinesium one? It's also available at close to half the price on polybound.co.uk (the claimed manufacturer - who seem to specialise in resin bound surfaces). https://polybound.co.uk/product/tools-equipment/25m-blue-extension-cable-reel/

I wasn't thinking about CH at all. Now I remember you previously talking about it being unvented. No matter, the HW cylinder/system can be dealt with independently AFAIK so no need to link the two in a single job. So no real reason to change it from a delapidations point of view. As far as maintenance goes, I remember you saying you were aiming to get as much done as possible before retirement so that you kept your costs low in future. Retirement also brings the future potential of not being as able to DIY as much. I tend to think that both of these lean more towards the unvented solution as it's simpler* but maybe not by a lot. But the backup water during outages is a big positive of the vented option. *Yes you have the PRVs and the associated maintenance. But these are all contained in an accessible heated/controlled space, no ladders involved, no float valves or pumps to play up.

🫣 Assume the HW pipes flow through these rooms to the kitchen/bathroom? Changing the HW tank shouldn't affect CH pressure unless I've misunderstood something. That is an advantage. My experience of cold water tanks in lofts is they end up with unpleasant things in them and are located in a diffcult spot for maintenance. Having said that you are not my relatives and are likely taking much more care of the system than the average person.

Without knowing about the extent of the pipework you are worried about leaking this would be my strong preference. Getting rid of shower pumps, cold water tank, etc, and if the pipework is fragile enough to break under mains pressure then chances it fails anyway at some point? (replace with point to point plastic with no joins if access isn't too bad?) Obviously, need to worry about the G3 stuff so you have less scope for DIY but overall I think you end up with less to go wrong in future.

Failing that, can you temporarily store it over winter and get rid of it after it drys out (potentially leaving time to co-ordinate removal to happen on a lorry that was coming to site to deliver something)? Double handling might make this a non-starter. But if you are doing the moving with your own equipment then maybe makes sense.

Saw something the other day. The BBC has cut its news budget by 40% in real terms in recent years. Given the big names command high salaries it seems likely that they are consuming a greater and greater amount of the budget with back ground research/beat journalists getting massively cut. Papers are similar. Their business model is crippled by social media and the lack of money in adverts these days.

Theres another benefit to starting now, even if you initially see minimal gain. It chips away at a bigger project, getting you closer to the goal. Once this is up and running, your list of things to do will be less daunting and more approachable. Plus theres always the chance that once the inverter is generating it provides you the data to justify more upgrades.

Some areas worse than others but yes. My feeling is they copied a lot of their workings from other flats that have 1-2m2 windows and applied it to my flat which has those windows replaced with sliding doors that occupy most of the external wall, then on top of that late in the design they changed the sizes of the rooms making one in particular 6+m2 bigger. The change in design for my flat means that they have got some other thermal bridging details wrong. The concrete floor extends without break onto the balcony for example.

Current ones all K1 except one

Not sure the manufacturer but the current ones are along the lines of these: https://www.stelrad.com/radiators/designer-radiators/white-radiators/flat/ £166 for K1 600x800, white £250 for K2 600x800, white If you upgraded to K2 600x1200, white, then £350 Existing are powder coated colour matched. Finding that option adds a lot to the price (looked at various brands all similar) Type 22 800x1200 white Flomasta is £58 from Screwfix https://www.screwfix.com/p/flomasta-600mm-x-1200mm-6998btu-white-type-22-convector-radiator/612xp#product_additional_details_container

Yep, lots of options, but I doubt I could manipulate the tails easily to do that and adjusting things behind the plasterboard would be the better looking option. I expect to repaint before selling anyway. New option occurred to me last night. I could replace all the radiators with Flomasta ones for not much more than the price of one new one matching existing and maybe even get some of my money back selling the old ones (though that seems questionable). It's a lot of work though and more than I signed up for when buying the wiser. Might meet payback though (especially if I can sell the existing rads). Still not sure if the style downgrade makes sense, but it's an easier sell if everything is consistent. Every room is different and it's good to have options!

Be funny if me linking to something that didn't do what I initially thought ends up being something you use! I do like the idea of using this in parallel to the Shelly, rather than programming the Shelly to do the boost itself, as you get the redunancy. But I'm pretty sure you could do with all within the Shelly and wiring a retractive switch to it.

If I decided I wanted to target full low temp system (ie, support low temps year round) I expect I would look to install wider radiators rather than go to triples. Triples will eat into the room in a negative way, longer rads not so much. But would involve redoing the pipework around the rads (and breaking into the plasterboard to do it). Having said that at this stage I think it's very unlikely I'd go that route. Sounds like a recipe for harmony!