Nickfromwales

Be careful what you say to him.....as he'll talk you into an apprenticeship!

Link These are what I use for a retro-fit where gas vs UFH is the remit and space is tight as they are wall-mounted. The 25 and 50L show as out of stock, so ask about availability. Other sellers are punting the same unit out for more money. Telford are now doing small buffer tanks, so if you require such a unit, contact Trevor from Cylinders2go and mention the forum and he will give you a discount.

Read the small print Over 60's are 5%, and under 60's need to have left 60% of the installation cost ( in materials ) behind to attract 5%. That's assets only, and doesn't include labour / scaffolding etc. Best to check your individual eligibility first.

How are you 5% VAT? Is this part of a large refurbishment?

I have found these to be rather complicated and somewhat unreliable tbh. I won't be using that system ever again ( and I've been installing central heating for nearly 30 years now ). Have a good read of the existing content here first, as this has been discussed quite comprehensively. You will definitely need to introduce a buffer tank to this setup to allow the UFH to run independently and reliably without short-cycling the boiler. Do you know if there is any insulation in the existing floors / walls? What is in the attic?

@Pinzameld Check out @Crofters blogs / posts. He’s done a demountable building under the same guidelines iirc.

Have many on here had comparative costs to go from a regular foundation system ( block and beam over trench or the type of system linked a few posts back ) vs a passive raft ( assuming screw piles are not required in each instance )?

It is a bridge over the possibly unstable ground in between the trenches. A raft over trenches in essence. It also gives a uniform level platform for the insulation to sit on too. Not necessarily a problem with a poured floor / screed, but a nice surface to work from nonetheless. Ground conditions are everything with foundation designs so proposals will differ site to site.

Yup. Male / female arrangement also, so no 'male' end on the light fitting itself can be touched when live and no connector inserted eg end of line fitting.

Agreed, and known. Yet OP pic shows that tooth which may be a manufacturer specific plug / connector vs the 'fits into anything, any way around' figure of 8 , and therefore it is likely the Interna plug / connectors will not go into the TLC fittings. Added for info so the OP can decide the best path.

I think it’s assumed that the overlay would either be a compromise / get out of jail solution, or would be atop an already insulated substrate. Let’s not get our knickers in a twist over a retrofit solution “it is what it is”.

Hence my phrasing “not necessarily”

Not necessarily. If it’s a 30mm system atop a 100mm layer of PIR or PUR then it’s a very efficient solution for the OP. Prob need to self level the block and beam to get a flat, uniform surface, so maybe allow 10-15mm worst case for that.

Usually only doubled up at the bottom courses but time will tell!

The item in the OP looks to be a polarity-conscious connector, whereas the figure of 8 is not? TLC offering is difficult to say from pics. Shouldn't really matter tbh but the OP item may need the leads cutting to create a hybrid interlink.

You'd have had to dig out regardless, for a decent sub-structure for the overlay to go atop. You'd have tried to make the overlay panels yourself, and we'd still be tiling if you went that way The overlay needs a solid structure or it'll all disintegrate.

What is the intended floor covering? Porcelain tiles? If so you can get an overlay system and have all insulation. https://www.wundagroup.com/underfloor-heating/wundatherm/the-system/

@Tyler Check out TLC directs offering https://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Lighting_Kitchen_Index/Linkable_Flourescent_Fitting/index.html

I meant in respect of the sprinkle system. It seems to be a knee-jerk, by some less versed individuals, to use the term sprinkler system where it should actually read automatic fire suppression system, which allows a sprinkler OR mist system to satisfy this requirement. For any areas where you may get false alarms, eg a smoke detector directly adjacent to / off a kitchen ( open plan area ), you can use an optical smoke detector vs an ionisation detector to reduce false triggers. "Ionisation alarms are very sensitive to cooking vapours and if placed near a cooker or toaster are likely to give frequent false alarms. Optical alarms detect larger particles of smoke, the kind that are produced by a slow smouldering fire before it bursts into flames." This will be as good an option as you can get to mitigate the issue, and what I've done for many previous M&E clients. It's something that any decent designer should have implemented as standard in any such proposal TBH.

Visual impact of the lesser diameter vs nearly the same depth = a smoke detector that does look like it sticks out a lot more as the shape doesn’t lend itself to being inconspicuous imho. Forst glance and I thought “ceiling tit”. Aico for me still, sorry, but thanks for the alternative suggestion.

Does this requirement actually not read "automatic fire suppression system"?

Sorry, my comments were on the assumption the surfaces were on show after drilling, whereas that is not the case. The best investment here is a set of very high quality ( Bosch / DeWalt )1000mm SDS drill bits at 10, 16 and 24mm sizes for provisional drilling. Drill the first side with the 10, then the 16, and then send the 16 through the rubble fill and into the second side. The 16 will stay relatively straight whereas the 10 will not. Go to next size up accordingly, and best of British with the rubble fill cave-ins. One trick is to drill the 10 and 16 and then get a closed cell expanding foam, push the nozzle in as far as you can get, and inject a punt or do of foam. Squirt some water into the hole first to soak the rubble fill, which will make the foam cure faster and spread better, and then leave for an hour or two. The cured foam will keep the rubble fill in check whilst you drill through and install the resin.

Ok, not great, could be worse. I assume you’ve got solar PV to offset the known constant electric consumption? Would be a no brainer for you as you’ll be using your excess without a doubt eg 100% self consumption would be feasible.

Start off small ( 6mm SDS ) and go up in 4mm increments. Should be easy enough that way tbh. When you get within 6-10mm of the desired size, use a diamond tipped hole saw to start off the hole, so as to prevent the surface breakout, and then put the same size SDS in to complete. Use a hozelock pump up spray bottle to keep the diamond bits soaking wet slushy cutting. Will the the remaining surface be on show afterwards?