PeterW

Samsung EHS or Daikin Altherma would be my choice after Mitsubishi. Only caution would be the Samsung is the internal unit is very large, the Daikin is much neater but they can be a bit more expensive.

Yours is different as it is a conversion/extension not a new build, so doesn’t need an air test. EPC should be pretty easy to get for a conversion.

Tiles need nothing under them - I would do the other walls with Super Leytex at least two coats before tiling though

You’ve latched onto this being “the issue” yet it could be one of many - and despite myself, @Nickfromwales @DamonHD @ProDave and @SteamyTea asking you to try the basics to eliminate a potential issue, you’ve ignored the requests. I have no idea if it’s the issue, and it could even be something bizarre such as the wind direction or the airflow over this sensor, but without having one more piece of information to try and help, we are all guessing. Essentially ignoring all the advice you’ve been given is like asking us to stand in the centre of circle and walk to the edge, but telling us we are walking the wrong direction ..!! So please either do what’s been asked and let us know the outcome, or don’t. But if you don’t, please don’t ask for any more advice on this as we are wasting our time.

Nope as it could be working correctly ..!! Until you actually do the tests we’ve asked then no one knows.

It is buried in the installer guide, and you need the passcode to get into installer settings. And I’ve no idea how to do that or what else it would screw up.

No more than any type of heating system. I’ve seen gas boilers throw more fits than a toddler just because they can ... And as I said, weather compensation is complex and even I don’t know “exactly” how it’s programmed into this unit but if you try a few of the things people have suggested, it may just help.

Buy a couple of sheets of 150mm PIR and build a box around the unit in the attic. It will be warm enough to stop any condensation.

Your backup will be immersions in the tank and potentially in the UFH buffer assuming you are having one. Sounds like your wood burners will also help with heat only, and if you want belt and braces then fit a single electric shower somewhere. All will rely on electricity though (as would a backup boiler)

Last door casing I bought could have been used as a propellor it was that twisted ... nothing wrong with whitewood if you can pick a straight bit with no knots.

Nope it’s a decent bit of kit and I would take the swap.

Screw the header to the top of the uprights and slide into place.

You can do that with 2 port valves but tbh they aren’t really needed as unless it’s over 2 floors, the temperature differential between rooms on the same floor is negligible.

Someone needs to tell Wharfe Valley and also Clearview probably need to check one of their displays in Stow on the Wold as at least one of the hearths in there is limestone .... https://wharfevalleyhearths.co.uk/what-type-of-stone-is-ideal-for-a-stove-hearth/

Limestone is very heat resistant ..! Your stove will also only get to 100c at most on the base - you’re not building a constructional hearth. If you want something different then soapstone is reasonably priced and looks good.

Sorry ..! Hoyland are good, meant to put do a quick google search for them ..! Black limestone looks lovely, you can polish it with a coating that can make Matt or shiny.

Most of the panel systems require you to use their corners for waterproof joins and the type Y from Multipanel is really neat. Allows you to align the boards when one has been firmly fitted. https://www.multipanel.co.uk/products/multipanel-profiles/type-y-last-corner/

Hoover what you can then suck a length of wool down the ducts and use that to tie on a piece of nylon cord. Tie that around a piece of rag and give it a good soak in anti bac spray and pull it though the duct. Worth tying another bit of cord to the rag to retrieve it if it gets jammed.

Yeh one or two other people have found this and oddly it seems to be the ones going onto RHI jobs that are causing delays. Samsung are fine, so are Vaillant monoblocks. Post the spec when you get it

£37 can’t be the loose price is it ..?? £17/t for 10 tonne and £15.80/t for 20 tonne currently. £34 for bags

How old is the boiler ..?? I’d be tempted to bridge the boiler rather than having that run through it or you could end up with more problems than you have today.

At what point are you planning on changing the rad system to flow and return ..? Or is the “plan” to do the whole ground floor with UFH eventually ..?

To meet building regs / Benchmark it now needs to be installed as it is part of the control system. So you can’t do that. It is the difference between the actual room temperature when it came on, the time to run and the target temperature. The system needs more heat into the room so the rads are hotter. Poached egg analogy all over again. Neither. It’s working as designed and to spec / installed. If a certain room “feels cool” then look at the other options / issues. Draughts from windows or chimneys ..? That will make a room feel colder than it is at shoulder height or where the thermostat is installed. Fix that and you may find your “cold” issue is reduced. I’ve tried - you said you didn’t understand the instructions and trust me, trying to simplify weather compensation algorithms to their basics is nigh on impossible unless you have a good understanding of physics. It’s not a simple replacement - the unit not only does the thermostat elements but also is linked direct to the internal hydraulic controller so is paired. Would take a lot of effort to change or replace. It’s working as designed and installed - it’s a matter of understanding the controls and how it works here.

Yes it is in the Town & Country Planning Act. A “building” only obtains permitted development rights when it is deemed to be completed to either the plans submitted and approved as part of the application, or it has been in existance since prior to 1956 (from memory) and those PD rights have not been removed either by a blanket removal on the area or by a specific clause of approval.

Heating on only and turn the pump up to max ....