Ed Davies

It'd be interesting to calculate what the incremental cost of adding, say, a metre to the width of @SteamyTea's house would be: an extra 26 m² of external area (gf floor, walls and roof), 7 m² of internal floor area and maybe 5 m² of internal walls and maybe a bit more cable and pipe (though not much pipe with sensible layout). The thing which wouldn't scale would be the joists - presumably they go across the house and 4.5 m long is significantly more than 3.5 m in terms of beefiness required, I think. Maybe a bit more window area. A lot of the other costs would stay the same, e.g., for stairs, plumbing, electrics and so on and particular for the side/partition walls. In exchange the floor area increases by 13 m² which is just short of a 30% increase. I really doubt it'd increase the cost of building the house by anything like that much (and why cost/m² can be so misleading for houses which are unusually large or small). They wouldn't fit across the front of the plot like that but that layout wastes the area of the access to the back. Putting four houses across the N side of the plot and two across the S side might have been better.

Interesting. Rather the opposite of what I had in mind: perhaps supply to 100% and extract to 30% would be better if you're switching on a separate extractor but if it's configurable to do that that'd be OK. Having a completely separate kitchen extract path might be simpler than valves and bypasses. I don't quite see the logic of reducing supply to 30%, though. Doesn't that just depressurise the house so the other 70% is made up from random leakage? A bit theoretical for me as, for most of the cooking I do, I'm pretty sure that a recirculating hood will be sufficient.

Why would cooking smells be spread through the whole house if you have an extract vent in the kitchen, which you would, of course? Would it make sense to turn off the extract side of the MVHR but leave the supply side running? Perhaps even boost the supply side. Do MVHR controller allow that?

AIUI, the air break is there to break a lower-than-atmospheric pressure in the pipe allowing syphoning to happen. But shouldn't it be an AAV - an air admittance valve [¹] which lets air in but prevents liquid getting out? [¹] Not an automatic air vent which lets air out but doesn't let liquid out.

Nope, a thermal store just stores therms; the actual water to be heated is not stored in it (apart from the small quantity in the coil which is completely changed every time a significant draw off is made so not much chance for bugs to breed [¹]). An unvented (or vented) cylinder also stores therms but also the water itself. [¹] Edit to add: maybe not even the volume in the coil if the heat take off is done via a separate heat exchanger.

I have one of these towers (the 7m version): https://www.aluminium-scaffoldtowers.co.uk/diy-access-tower-sale/ 7m refers to the working height, the height you can reach so 2m above the highest platform height (5m) and the highest handrail height (6m). For lower heights it's very useful and I'm OK on it at the maximum height but very nervous of handling even quite small sheets unless it's dead calm and would not be even slightly interested in silly tricks like pushing ladders around and climbing on and off them. If your gutter really is 10m up then something quite a bit more beefy is called for, ideally attached to the wall (tied off through a window or something). As above, DIY might not be the best option.

…and two different time zones: https://www.youtube.com/watch?v=QCwpVtqcqNE

But everybody on that thread is in England (edit: plus one in Wales).

I think they can if it's been more than 5 years. Given that it's obvious I won't be finishing soon they took the option. You don't have to retrospectively change anything which has already been installed or would be impractical to change in the design so it's not that onerous. In theory they could have asked me for a new SAP calculation but I'm so far clear of that that they waived it.

I wonder how they'd react if you just set up for PH levels and say so. I've just been bumped up to 2017 regs on my most recent warrant renewal so this thread was a handy reminder to read the 2017 ventilation rules, which don't seem like much of an improvement in clarity over the 2013 lot. The other changes which affect me are the need for a CO₂ monitor (which I have anyway) and the need for robust walls for fitting handrails in the shower room which other discussions on this forum had prompted me to think about, too. So not a hassle really.

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11461&page=2#Comment_193433 There's some quibbling further down the thread on how the volume is calculated when the ceiling is higher.

What's the purpose of restricting PD rights for ASHPs to heating only? Is it a general prejudice that cooling is wasteful or is there something more specific? Perhaps that neighbours are more likely to have windows open when cooling is needed and therefore be affected by any noise?

There are all sorts of possibilities depending on what the manufacturer felt like. The mention of modbus_rtu on the error screen points to differential async serial comms of some sort. Whatever, it'll be down to the details of the protocol whether it matters which end is switched on first - for any sensible Modbus implementation it shouldn't matter. At worst switching the controller off and on, with the main unit on, should recover if it's a simple protocol error.

It's not 100% clear but it looks like it's the main unit which has failed and the controller is just moaning that it can't get a sensible response out of it.

Good idea. Probably worth doing that at both ends together.