Andeh

I would think several large 40mm+ concrete paving slabs under various structural points would be plenty to share the load. Ensure all are level using a biscuit mix of concrete/sand to help as well.

We will have 2 x MVHR when we move in, which we are approx 3 months away from. We will regularly spend a few nights away from home & I am fixated on trying to keep energy costs down. One MVHR will be in our loft space, with boost switches in each of the bathrooms to manually boost it. Another in a cupboard - nether easily accessible for a quick 'switch off on the way out the door'. Can anyone with Vent Axia MVHR's talk me through the control option's for them? ie: 1) Can I use any one of the ''boost switches' to simply turn the whole unit off? 2) Can I/do they allow WIFI control so I can do it via my mobile? 3) Is there a way to remotely install (do i need to hard wire a cable now?) a control panel to enable me to switch off the units without going into the loft? Many thanks,

Thank you for coming back and confirming this, well done for resolving it!!

Yeah, I really wanted a single big unit for the power usage reduction, but house design just blocked it outright. Was a none starter unfortunately. I have done my best to ensure a gradiant through the pipework down into the MVHR, and the vents have large overhangs to help limit driving rain getting in. Is 1.2m separation OK on external vents? Manual doesn't recommend anything and I figure with the unit likely to stay on 20%, nearly 2x over sized, and an above average windy location will ensure no cross contamination!

We had a company out who designed & installed our 2 x MVHR. We had to have two due to an middle entrance hallway separating two ''wing'' of the house preventing pipework. The smaller unit is a Vent Axial Kinetic B....the installer didn't install the inlet & outlet rigid ducts due to not knowing where we were going to punch through the flat roof above the units location. As a result I have been installing the inlet/outlet ducting myself having worked out where. However, no where in the manual does it state dos/don'ts nor requirements for the inlet/outlet ducting, and due to the Christmas hols the installer is offline to guide me, but I need to get it all done due to the plaster boarding starting when we get back. I have used 125mm rigid ducting, have installed the ducting so that the externals are 1.2m apart in the roof & done my best to ensure there are no 'low spots' for moisture to pool. I will double wrap them in insulation, just because I have that quantity. I will wrap each joint in aluminium foil tape to ensure it is secure. is there anything else I need to be aware of, before I secure it all together & wrap in insulation? Thanks, Unit: Lo-Carbon Sentinel Kinetic BH | Vent-Axia# Manual: https://www.vent-axia.com/file/196379/download?token=EZMXaPT-

Afraid I can't help much other then to say Bravo, there's some serious history in those ASHP!! 😨 Are you able to add any more insulation anywhere in the house? As with laptops & mobile phones, what was high end 10 years ago has sadly moved on now, insulation standards being no different.

I wish!!

Thanks all, I can do that worse case, just trying to avoid the cost if I can help it. Pictures might help.... We have had 3 of these mezzanines/galleries built. using 220mm x 45mm joists joined together to form a 220 x 90mm master beam. This has left us with a lip, that is a trip hazard near the staircase we will install. As a result, I want them to trim this lip down, and add a third sistered joist to form the ultimate 150mm x 135mm master beam. Online span calculations show that for a joist of 72mm x 145mm will pass a room width of up to 3.4m at medium loading (400mm joist spacing, as ours are). With our desired joist being 150 x 135mm, this should far exceed the minimums, surely?# Free UK Span Table for Domestic Floor Joists to BS 5268-7.1 (C16, 1.5 kN/m² load) - Timber Beam Calculator [img]https://i.imgur.com/KfWZnfZ.jpg[/img] [img]https://i.imgur.com/IWyJYjk.jpg[/img]

Please post the results of your investigation. We're in a rental new build, 2019 build, EPC 86, airtightness of 3.5 "as tested". The fact I have gone round and sealed up the drafts (incl a tea towel in the Extractor fan it got so bad...) lead me to believe they bullshited the test. Rest of the house and windows bleed heat at an appalling rate as well as well, I'm furious on principle... Even if I don't own the place I'm disappointed in it.

Brings me back to my headache of an engineering degree I struggled for years, made a success of it... But also made a habit of being the most non engineer engineer ever! Timber joists, I should have added!

Our amazing architect left the firm, and the firm are being hopeless at covering the work with her gone. As a result I am trying to cover some bits off myself. We have some galleries/Mezzanines going in, which span the 3.1m width of the room, with 400mm centeed cross spans. To keep the Mezzanine as slim as possible I want the main cross beam to be 150mmm x 145mm in effect. This is outside normal span tables, can anyone point me to something building control would recognise? Thanks

We're hoping to be boarding 2nd week January! We're still holding pressure, though I think it's dropped by 1 bar over last few days but who knows with temp fluctuations and it all still temporary bunged up. Either way, hoping we got away with it! Got fingers crossed for you. Please keep us updated

Watching this thread with interest, I'm in the same boat!

Outstanding work OP. I want to build a cavity just to give that all a go myself!!

How did thing's work out for you Prodave?

Useful thread!! Building control have approved our Mezzanines (similar to OP's) with a ladder and handrail. Mezzanines installed by builder already. I am trying to get architect to ask them about a super compact staircase with right angles corner half way up. I figure safer then standard ladder and handrail... But we will see their verdict. I'll try and remember to post photos tomorrow.

Hi all, as per title. I am ideally looking for something that sits below approx 250mm tall? Just so not visible from the driveway. 125mm spigot needed for my 125mm ducts. Many thanks,

Thank you, that's the one!! I thought they gave it more air time, so obviously jumped over it as I went through my 5-10min chunks per episode.

Out of curiosity, what is the fix if it is worse case scenario, floor up with concrete via cutter/jack hammer, pipes pulled out, re-laid & rescreeded? (few days per room?). Or bury a pipe join in the damaged section, remember where it is & check pressures monthly until you forget about it? (for what its worth I lived for several years with two UFH couplers in our airing cupboard following a manifold move after installation and they never so much as wept once.... )

For what its worth OP, I have spent all day on the phone to my builder, his plumber, his site supervisor been on & off site three times etc trying to check my own exposure to this, i basically just didn't turn up for work today. My builder is 3rd generation, a wily but incredibly competent, professional, experienced individual & he is totally confident of this being a very very low risk of pipes freezing in concrete. He never said 'never' but felt it was incredibly unlikely, unless fittings are in there, dodgy pipework fitment, damage etc. I am a Mechanical Engineering by profession, and have real OCD on my build, and he still impresses me with his competency on a regular basis. He/supervisor/plumber etc have all seen fittings pop off, manifolds leak & pipes split when they are outside outside, in -8 degree temps...but for pipes to freeze in concrete is one he has never come across. Out of sheer stubbornness & frankly just telling them to 'do it for my peace of mind' I have convinced our lot to wire the two UFH pumps in & run all the circuits on a high flow rate to keep the water moving, i've got heated oil rads boxed in with insulation near the manifolds to try and get a tiny bit of warmth in them & the team spent an hour sealing & insulating all our open apertures (we are missing two big doors & some large sliding doors) before finishing today...... Just to try and limit any damage/further damage our end, its sat sat totally exposed for the last week before I found this thread & paniced myself.

Hi All, I am worried about frozen UFH pipes in our build, and want to show our builder the grand designs episode where an elderly women's UFH pipes froze & she had to have the floor replaced. i thought it was 'the Streets' but having flicked through the episodes, I havnt seen the house or scene I am thinking of. Can anyone remember which episode it was!? Many thanks in advance!!

Thanks Dave, yeah - really not sure how to proceed. They have agreed to drain the system as best they can, and ill ask them to seal the place up more so! Not sure there is much else we can do other then fingers crossed.

Long chat with my builder, and his plumber. Both long standing and both gave proven fastidious. Neither are the slightest bit worried, nor have ever come across pipes freezing and splitting. Both have seen joints fail, manifolds spring leaks, fitting come off through frost but both were totally comfortable with the pipes. Not sure how I feel about it, but I can't force them to do much, though they are going to drain as much of it as they can for my peace of mind. When I told them about that grand designs episode where the Ufh froze and split they were very surprised, and asked me to find the episode. Could only suggest damage during installation (rare) or very cheap/old pipe work.

Good luck, I spent an 90mins middle of the night checking our floor, our pressure was at 4.5 bar. Floor temps looking worryingly low (-1...) though. Heading back in 30mins to meet builders team when they arrive, and will be ringing him on the way. Feck me.

Welp, you arnt alone losing sleep tonight! Good luck to us both.