MJNewton

Yes, there will be a vacuum due to the fans being positioned such that they suck air through the unit rather than blow it. It won't be an issue once the drain is connected to a trap.

Adding to what Stones has said about the misleading perception from using your hand to detect extracted air flows, if you've got access to the exhaust vent (even temporarily removing the ducting to it if need be) you'll get a much better feeling of flow by checking there. Of course it'll represent the total whole-house extraction but it'll still give an indication of things operating as expected (or not!).

One thing I do find useful, which might be related in some ways to easy access like a slide-and-hide door, is telescopic runners. I assumed they were just going to be an smoother-running alternative to a normal pull-out wire shelf but actually they are streets apart. Really easy to slide regardless of weight, and much more stable with no tilt like you often get with just the wire shelf. I'd certainly factor having those, more so than a slide-and-hide door.

Apologies - I misunderstood what you were saying. I read it that you must discharge externally.

Are you sure? Our PRV discharges to an internal soil stack via a length of copper pipe to a tundish, HepVO valve and 32mm 'plastic' (not sure of actual material/markings) waste pipe to an internal soil stack. I believe it is quite a common setup these days.

Definitely get the MVHR going as the heat recovery will lower the RH of the incoming air and help with evaporation.

What?! *Now* you're telling us you're using a plug-in network adapter?! Talk about a wild goose chase. Yeah, if it's cheap Chinese nonsense then you can almost guarantee non-unique MAC addresses. Buy something better quality and your problem will be solved.

With the ducting being fully lined I wouldn't expect it to be an issue, assuming the damage hasn't gone all the way through. If it were me I'd wrap it in duct tape just to be sure. Actually, I'd probably wrap it with aluminium tape first then duct tape as I like to over-engineer things..

And likewise with neighbour support.

I'd suggest going with the Shelly relay option acting as the boost controller with physical switch inputs thus giving 'standalone' functionality with no external dependencies. You could program different boost durations for short vs long switch presses if you wish. If you then wanted to add event-driven HA control later just get HA to request the boost via Shelly's HTTP API.

I'm Brian! (And so if my wife!)

In case you were being serious there (hey, you never know! ;-)) are there any similarities between your setups e.g. same OSs, perhaps one built the Pis for the other etc? MAC addresses can be changed and it might well be the case that your OSs are changing them (to a fixed value, which is a bad idea).

In theory, I suppose anything is possible. In practice it's not going to be the case. Occam's Razor suggests it is almost certainly a router issue, not least given the majority are built down to a price and are full of bugs.

They're all going to be different, otherwise you wouldn't be able to use them on the same network.

Does the router allow you to enter the MAC addresses manually? What router is it?

Most large suppliers will provide a national service so don't hesitate to cast the net wider unless there was a preference for a local supplier (which I could totally understand).

How are you discovering the MAC addresses? On the Pi's themselves (running ifconfig or similar) or is it from the router's view of the world? If the latter then it is likely getting confused and/or showing misleading information. The MAC addresses *will* be unique so keep persisting...

Aha! I was born and bred in Macc... (parents and other family still live there)

I'm not sure of the motivation for nighttime setback as the power consumption is relatively low anyway and with a well designed/installed system there should be no issues with noise.

Out Titon unit uses plastic framed filters that they sell direct for £12.75/pr: However they can be easily refilled with other filter media so I bought 1 sqm of 10mm G3 media for £8 which should do me for about 10 swaps. Not only will it save a lot of money but at 80p/service I figured it might make me less stingy about how often I do it too!

Howcome? I don't recall ever seeing double glazed units that require toughened safety glass to only have it in one pane. Even aside from what any regs my say (I don't know what they do say) it doesn't make sense to me one pane would be left untreated. I certainly wouldn't have overhead glazing without safety glass - I'm surprised it's even available.

I'm waiting for our Ideal Icos to eventually reach retirement (not a single fault in its 14 year life so far but I can't expect it to last forever) after which I'll be going for an Intergas. They appear to be highly specced but very low component count and easy to repair. As of 2018 they said they hadn't had a single reported failure of one of their heat exchangers. They fully support Opentherm too so give a good choice of independent controllers rather than tying you in to the boiler manufacturer's own offerings like many do (e.g. Worcester and Baxi) if you want fully modulating control.

I believe intumescent strips are only required on the top and sides of the door.

Okay, that's not sounding too bad at all in my view! The Vent Axia clarification regarding inlet-exhaust separation and the non-applicability of the straight exit pipe length are particularly helpful, and as I said I regard them as the expert witness in this case then you've got to go with that they say. Besides which, your 900mm separation is some way beyond the 300mm minimum and whilst it might not be all the way up to the supposed 'ideal' personally I'd be happy, and I'm a fussy bugger. Picking up the repair costs for the stone spalling is fair enough too, assuming of course whoever does it does a decent enough job and I think you've got to give them that opportunity to do so. Ideally the damage wouldn't have been caused in the first place of course but that ship has sailed and you've got to accept the reality of the situation. I am a little surprised about the ceiling plenum issue - I thought he was going to say he'd send someone out to improve the mountings as remedying that sounds fairly straightforward to me. Maybe the 'required information' is about who is going to come and do it? All in all though, I think that's a very good response. Polite, well reasoned, considered. And what's more - an actual response which can't be taken for granted these days!

I think it's a Linksys mesh WiFi access point (if that's what you mean). I suspect it's a 'TV' corner, although it's a very small room. I used to put in multiple doubles for my AV stuff but always found I'd still run out of sockets so realised I might as well just use multi-way socket extension leads, although I seem to have far fewer devices now that so much has converged and streaming taken over.