Nickfromwales

Don’t take pipes so close to the perimeters. These should observe around a 200mm gap to allow heat to diminish before a cold bridge is encountered; this reduces heat loss to the fabric of the build as is generally observed as ‘good practice’.

Ok. Let’s stop. The perimeter around external walls is a different detail to the internal ones; one has heat loss outwards, and the other is part of the heated envelope. The external walls need the 23-30mm PIR up-stand (or a bit more if your flooring can cope) for a thermal break. So that’s where that’s needed. Size it to be at least an inch higher than top of screed, so your screed doesn’t spill over the top during the pour. Then, the perimeter insulation (foam “skirting”) is applied over that at external walls, and is simply stapled to the studs for all other (internal) walls. Some 30mm screws will be suffice to pin the skirting to the PIR, literally pushed in by thumb. Some have the self adhesive strip, that is also suffice (I mention screws for the ones that don’t have this, as not all do). The screed rolls out over the taped-down apron (the affixed membrane of the foam skirting) and that stops any movement, and stops screed getting under and out. Nothing ‘floats’ as you’re not pouring screed under it. Friction from the weight of the screed pushing out against the foam skirting holds it very firmly in place. Do away with this perimeter insulation skirting at your own risk, but some screed companies will insist upon it so check before they arrive; you don’t want them refusing to pour because of some cheap strips have been omitted. The skirting sits on the floor insulation, tight down against it, and should also finish at least an inch higher than the screed. Once cured you just lay a multitool or old handsaw against the screed and cut away the inch excess of both PIR and skirt strip. Lay flooring, move to next problem. PS, I’d use a cementitious screed vs gypsum. Much better / easies eg less time, mess, fuss as you’ll be mechanically scrubbing off laitence etc so you can stick stuff to it.

Hi. Something’s not right if your design flow temp is as high as 35°! GF UFH, I assume, is going into a slab? If so, 35° into that will cause the house to overheat. You should be mid-high 20’s and certainly under 30°, if well built, airtight, and you have heat recovery too. Buffer “delete” may be subject to the manufacturer’s installation instructions, and an MCS reg’d installer may refuse to stray from that. On a recent Heat Geek install I witnessed they put either a 25L or a 50L 2-port volumiser in, on the flow which makes more sense to me, as that was stipulated in the MI’s vs what the low heat demand called for. That was a refurb, prob got to EnerPHit levels, and the flow temps at 25° made the place almost unbearable to work in. @jimseng As we don’t know much about your particular project we can’t possibly size a heat pump here yet, but 3.5-4kw will be quite slow to reheat a decent sized UVC; your game plan needs thought which considers your DHW needs / frequency / number of occupants. Heating is a doddle to resolve, DHW needs to be considered in isolation and planned for pragmatically. You can, for eg, use an immersion strategically to boost for times of duress, so many ways to ‘make this happen’. Do you have solar PV in the plan?

@junglejim Does the picture depict your situation? Masonry build with a cavity?

The frames provide the support, the walls around them just hold the tiles. No need for ply or doubling up of anything. Done a load of these over the years and never any issues whatsoever, ever with the Duravit, extra-long projecting pans. 6’2” Canadian was asking if they would move, so I stood in my socks on the very front edge and bounced up and down. MBC TF house and all supports / studwork done in chunky timber, and client was going white waiting for the pan to snap off the wall (which it didn’t). These are rated to allow for a human to trip and fall onto them, so landing your arse down with a less-than-graceful ‘thump’ or slipping and falling onto these is accounted for; impact rating of 60-odd stone / ~400kg or something iirc. Just do NOT use the stupid gasket they sometimes include, instead I mask the tiles and set the pan back into a bead of clear CT1, tighten up and level off, and then remove the displace sealant with a load of cheap baby wipes.

Hi and welcome. Are you aware of the zero VAT rule, if you decide to use either a bulldozer or an excavator to knock it down?

You can have the heat pump tbh as most modern, inverter-driven heat pumps have a very low inrush current as these ramp up vs ‘turning on’. Also, if gas is available, you could go for a hybrid ASHP with a gas burner (Grant do these); whenever the heat pump becomes overwhelmed the gas burner kicks in to fortify output. They’re a bit pricy though.

I have to ask about the exterior 'screen'? Don't you feel it interferes with the views? Lovely corner windows, great views, and then you look out onto (into) the additional timber screens.

You'll be surprised at just how much you can abuse an 80a connection. You'll not actually be doing as much 'constant, full-wallop' consuming of the juice . These things are a lot worse on paper than in reality. You'd not believe what one previous client was running off a 60a connection previously, when I was approached to refurb and add PV, and that was a large property full of electric showers / all electric cooking / fully occupied, and a self contained annex with the same all-electric setup in there sharing the same supply.

You have a bit of luck, as the base of each handle has those larger 'feet', so I would just drill incrementally up in size until you get to where you need to be. If it's up/down, then maybe use the 5mm bit to just elongate to make a slot, vs making bigger holes, plus you may need to fit washers to the screws so they don't pull into the (real wood) of the door and then move back to where you don't want them to be from the tightening action (rotational movement of the pan head screws). Very slow and very steady wins the race, so don't do this in anger.

UVC doesn't give higher flow rates at the 50o+ temps? Combi's can't usually be compared. 3 showers is very good, at what flow rates?

Mostly pics tbh

You’re still always constrained by the physical max flow rate of water, whatever temp, through a combi.

My books are all still wrapped in the cellophane as I didn’t bother going for my NAPIT in the end; Covid put that on ice, and a change in career path (coming away from the coal face) put it to sleep. Maybe I should give them a read lol.

Yup. Nails are soft, screws are hard, and those bits (and the Erwin ones, as long as you buy the correct ones)) are defo rated to go through nails; I have these and they plough through nails with relative ease. Screws is a very different thing as there’s nothing other than diamond that eats those. The Starret bits do go through, but after a few holes / screws you’ll defo see the teeth beginning to fail. I treat these as a consumable and just but multiples of the go-to sizes and bin when they start to struggle. Same with flat wood bits, just buy cheap ones off amazon, boxes of multiples of 12/16/20/25/28/32mm and treat as disposable. If the know there’s a screw, try to remove it, if you’ve gone through nails, whack a screw in after to reinforce what you’ve removed. Another joyous day of house-bashing. These are the best ones imo, if you’ve a whole house to 1st fix for plumbing and electrics. LINK