Nickfromwales

300w you say? £14 https://www.amazon.co.uk/winnerruby-Portable-Electric-Travelling-Efficient/dp/B08LNMHCZW/ref=asc_df_B08LNMHCZW/?tag=googshopuk-21&linkCode=df0&hvadid=554322167175&hvpos=&hvnetw=g&hvrand=8526765289628865508&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007460&hvtargid=pla-1458892795428&psc=1

OK, thanks. OK, so a room off an otherwise already heated room? Or a doorway between the two spaces? Assuming 3 external walls, an adversely cold floor, and the height plus Velux. 200w/m2 is quite an aggressive in terms of UFH, so you'll likely get under and over shoot, exacerbated by the floor temp probe and the room stat both trying the manage that heat input to floor vs heat getting to space scenario ( so they'll be constantly squabbling tbh ). Heating the room ( space ) will require turning this on a good while before using the space, so you'll need a self-learning stat like the Warmup 3 or 4iE / other stat / controller that offers that feature aka "setback". These work out how long it takes from inputting energy into the floor to getting the air temp of that space to the required stat temp ( 20.5oC for eg ) and it then alters the switch on time to allow it to come on sooner than the timer is actually set for. It will be very slow to react, will overreact due to the minimal 'thermal content' of the heated emitter ( you wooden floor ) so really not advisable. You'd be FAR better off with a tiny oil filled radiator, which will heat that space up pretty much instantly and waste next to no heat. Hopefully I have helped you understand why this is a bad idea.

Try shouting "chop, chop, it's looking like rain!" every 30 mins

Why are you heating this space?

FYI, there are different temp kits giving higher or lower w/m2. Have you calculated this?

OK. The issue often overlooked is with soft insulation boards used under the electric UFH and then furniture feet etc or other point loads cause the insulation to compress at that point as the floor covering isn't spreading the load enough. Engineered wood will be fine. How often will this be used? It will be relatively crap in heating the room, and bloody expensive to run. Is this in conjunction with a radiator in this room so is auxiliary heating only, or is this intended to heat a room by itself?

Insulating the condensate pipe, regardless of size, eg if there's a slight risk of freezing, is observed in most installations if it's a cold roof space. Will be a few £ and you'll be insulating all of the other water pipes too, so an extra 10 mins work at most. I'd prob leave at 21.5mm and insulate, as a risk of freezing will provoke insulating regardless and larger pipe sizes will attract more expense on insulation.

What is the chosen final floor covering where the UFH wire is going? Before all of the above, you need to know if it CAN be used before HOW to use / lay it.

This names specific companies This did not. No experience of Pimlico. Regarding British Gas, one of the biggest bunch of unscrupulous thieves I've come across. Indeed, they specialise in fleecing the elderly, I've recounted many instances on here, and that extends way beyond London I assure you. Best to remember though; Plenty of decent folk out there who are conscientious and diligent, trustworthy, and proud of their work.

Don’t talk out of your arse Mark Plenty of good fitters, in varying methods of vehicular transport, will sort this quickly and easily. Even ones in sign-written vans! @DamonHD Save the growing drama and despair, and just fit a secondary EV. Not really a situation that requires talk of planning permission Let’s not let this molehill become mountainous….. 1 - 2 hour job max, couple of £hundred max. Done and dusted. Thank me with beer.

The insulated rafts are more about low energy / high performance, ergo the reduced heating costs for the life of the dwelling is usually the where most attraction to this type of foundation comes from.

Stay clear of iMist, their price was nearly double what I paid. When I said no thanks and disengaged with them I got pestered continuously by email asking me to proceed. I said no thanks again, after they then started ringing me as well as emailing me, and they knocked a grand off. Then did that again, and again until I got so pissed off I wouldn’t have used them anyway, even if they became cheaper.

Hi. I sourced a 3rd party company and commissioned them to undertake the turnkey installation on my behalf. I do this with multiple different disciplines now, PV / MVHR etc. Contact Sian at Firemisting Ltd Link as they travel countrywide, as do I, which is handy. They’ve done a great job so far, and are due back to 2nd fix for me November. I am only supplying them with a 15mm dedicated cold mains supply and an unswitched DP 13a fused spur for power. Only a certified designer can specify and install the system, btw, so you won’t get a commission only package from anyone reputable. Nor would you want to?

SE, apologies. That’s a black and white scenario so shouldn’t attract such complications or elongation. At the very least they should have identified any “issues” and requested that you mitigate? I provide bespoke slab penetrations details on each of my clients new builds, and have never seen this level of ‘confusion’ tbh. I sometimes get a nudge when we’re close to steels in ring-beams, but that’s usually resolved in a day. Too many people being over zealous with “covering their arses” these days, and always at the clients expense. You’re not building in Gravenhill are you? In-house BCO’s there are “interesting characters”………😕

Hi. The gaps under the threshold are unacceptable and zero requirement for disabled access compliance. Complete and total bollocks, I’m afraid. Negligence in setting the entire door / frame unit in, to be sympathetic to your chosen floor covering is just poor practice, and again, shouldn’t be tolerated. Damp / water ingress from outdoors to inside is a fundamental installation error and that should have been mitigated BEFORE the unit was installed, and cannot practically be done retrospectively afaic. The unit needs to be removed and reinstalled, with those measures considered and executed correctly. This is utter nonsense, and simply fails to accept the problems which 100% defo exist here. The unit needs to come out, there is no other way. That will allow for the threshold height to be set to the internal finished floor level ( ffl ) according to what you prescribe that to be. Tell this muppet “no sale”.

Time to get him to justify, or get rid? Stinks of too used to them going unchallenged.

Says service drain off resides behind the PRV. Are you going to tackle this, or delegate?

@markocosic

On the potterton there should be a jig under the boiler which lets you isolate the heating circuit, and then an integral service drain ( small one not like the type you fit a garden hose to ) to drip pressure off without losing all the inhibitor / primary water out. You may need to remove the cover to find the service drain, can’t remember exactly where that is sorry. MI’s will prob show these instructions, just need to know exactly which appliance it is.

Have you yet discussed this, and convinced ‘us’ that getting an existing dwelling airtight is practicable? Not sure if you’ve looked into this fully yet? Horse needs to be in front of the cart

OK, explain this properly, please, as it is the entire cause of this thread. Adding an external expansion vessel is absolutely fine, done it to so many ‘awkward to repair’ combi’s I’ve lost count. All you need to do is add a secondary CH circuit isolation valve, beyond the point you T in for it, so it cannot be isolated inadvertently with the boiler “lit and burning”. Regs for this are open to translation, and as a very well versed individual I am sure you could mitigate against a 3rd party shutting off the isolation valves ( provided by ( Baxi ) Potterton ) to sleep soundly at night? Maybe just round off the original fitting so it cannot be shut off, for eg. FYI, I’ve fitted numerous Baxi and Potterton combis over the years and they’re damn simple and robust units. The Potterton is a budget Baxi, but still a decent boiler, and very easy ( and simple ) to work on. ”may be on it’s way out”…… Reasons why / for this statement please? Sounds like a storm in a teacup to me.

Are you going with radiators instead of UFH? Why has a high temp ASHP been spec'd? They're a PITA wit a noisy obtrusive internal unit ( internal as in indoors!! ) and efficiencies will drop like a rock if the HP is married to a system that isn't sympathetic to the favored input temp / operating conditions. A HP will also not recover ( reheat ) the cylinder as quickly as a boiler, so that is another reason to go for the 300L cylinder ( 120L would be getting ripped out in a few months, after you realised it was an epic fail btw ). High-flow gas combis have a theoretical matched capacity to a 200L UVC, for eg ). Can you not suitably engineer the build fabric ( insulation and draught-proofing ) and therefore reduce the heating system so as to be able to accept low temp heat from a monoblock ASHP? You buy insulation once, for the lifetime of the dwelling, but energy input ( running costs ) to mitigate against any poor decisions made now will be ever increasing.....

Fitted a Panasonic in a front garden, detached house but neighbours 1m away one side, no gap the other. The client and their neighbour have been stood next to the unit having a reasonably quiet conversation and the neighbour failed to remark on the unit, even though it was heating the house at the time. Apart from a little additional noise every start-up, the unit is VERY quiet indeed. The only time you’ll hear it, is when you’re trying to hear it, other than that it will disappear into insignificance in no time at all. Would be considerate to not time it to come on at night, in the summer, to heat hot water. We planned some living ‘acoustic barriers’ to surround it on 2 sides, aimed at deflection and to counteract the surfaces I worried would offer reflection, but seriously not needed other than for aesthetic reasons.

If going to an AAV, completely pointless putting it outside, other than not needing boxing in / service access to it if it’s mounted internally. The SVP is placed outside so the stink goes to the clouds, that’s the only reason to take the pipe out through the external wall.

Not at all. Just remember that replacing a soil and vent pipe ( SVP ) with an air admittance valve ( AAV ( btw, Durgo is a manufacturer of an AAV like Hoover is a vacuum cleaner )) you no longer vent your system to atmosphere. If you have neighbours either side with SVP’s then you’ll be fine, but if you are end of run I would recommend you preserve that point of venting the sewer gasses. On the soil / plumbing side, you sound in over your head. Part with some money and get a plumber to support you. Nothing stopping you T’ing into the stack to keep a WC pan connected and working, whilst using that run to carry on to the new location, then swap over in a day, blanking off the temporary loo. Just rotate the branch ( T ) when no longer required, to get it bellow floor level, and fit a cleaning eye / rodding cap in the branch to block it off.