JohnMo

Here is a video showing how best to split flow temperature. https://youtu.be/LL6YhT_HkIY?si=gMktTxr_SCWROGSW to

Each one of your options is not really insulated at all. The horizontal webs have to insulated from the outside world. The PIR is really doing nothing to help you. Draw lines start at one piece of insulation and if there any gaps in your line, you have a thermal bridge to fix.

So not exactly small at 500m². It was most possibly huge before the son moved out. Thirty-two solar panels were put in place at £400 each - insane, nearly £13k on solar - they only cost £50 each, plus mounts and inverter.

Air will take path of least resistance. So if your air being supplied at the green X's air will just move to the red X's and not really wash across the room. Can you get to the vertical face of the vaulted kitchen? I would suspect the dining room supplies make the ventilation in the kitchen worse rather than better. Because the short cut the air can take. You would actually be better supplying excess air in study and sitting room and having kitchen extract in the vertical face of the vaulted roof. Why two supply and extracts? Have you seen mapped out all the vents on the different floors and tried to understand where the air moves to and from, to make sure the whole house is washed with air?

That's the main issue, all spray foam is just used a blanket term and all are classed as bad as the other. So two types closed and open cell. Ours is. So anything wet can find it's way back out again via a breather membrane. Daft thing is PIR insulation is just another type of spray (expanding) foam, just made into sheets in a factory and covered with aluminium to make sure it completely moisture tight. Cowboy firms and a dumb press are is all I have to say.

1. yes and no see below 2. yes manual balancing is ok 3. I think the flow temp will prove too hot for the UFH. If you try to control with a normal thermostat you will have big temperature swings. If you are planning to use thermostats to control your boiler is likely to short cycle, and lead to increased gas consumption. 4. Over heating will occur on anything other than the design day. Excess in rooms means those room are super hot, they will transfer to other rooms but not before melting your current room first. Why not Weather compensation? You need to be careful with boiler flow temps, they will shift and overshoot by a big margin especially if they expect to see a thermostat intervention which doesn't happen. I first tried my boiler on a fix flow temp and the boiler got to 60 degs before I noticed. If they operate on WC they operate in a different regime and try to keep boiler flow temp pegged quite tightly. Depending on your boiler make you may be able to run an ESBE mixer on the UFH, this should not need an additional pump.

Plus it has to be pulled tight, when installed, so almost impossible to install well or correctly.

You don't need a buffer with UFH, especially so on a single zone. UFH (cooling mode) will not have any condensation issues, as long as you keep flow temp sensible. Sorry that price is bonkers. Priced up the materials for mine the other day (192m2 worth) well less than £1k, took me on my own two days to install. You need 16mm Per-Al-Pert pipe, pipe clips and a manifold for each floor, you should be able to drive the whole lot from you heat pump, circulation pump. If you don't want to go to bother of balancing or paying someone to do it, install Salus Auto balancing actuators and connect so they are all powered all the time. Once you get well insulated and especially with UFH 22 deg starts to get uncomfortably hot - that's anywhere in the house. Fan coils alter output by varying the fan speed, they have a fixed throughput of water, so keeps the heat source happy. So not comparable with a normal UFH where the circuit is either on or off. We started with a thermostat in every room, it just made the system so expensive to run. At the time we were on a boiler and its gas consumption was double what it should have been due to short cycling. Slowely removing the thermostats go us to calculated gas consumption. In the end we had one thermostat. Have single wireless thermostat, so you can move once you move in to best location. Do not accept a thermostat that does not have a 0.1 deg hysteresis option. Computherm Q20RF are nice and do cooling and heating and drive multiple receivers if needed Your certainly being taken for ride on pricing.

Yes carpets. It's fine with harder floors, but with ufh being so slow you can bedrooms way to warm or cool not really a happy medium. We just have just opted to have the bedrooms cool, open the door at 6pm, then it's fine for sleeping - not too hot or cold. We are long thin single storey so can two slightly different temps, from one end of the house to the other.

Something like this allows just battery or battery and solar and or generator etc. so pretty flexible. That's from City Plumbing, many other similar units available depending on size you want. You would need cables etc and they would be pretty chunky.

Just looking at your drawings you have a lot of thermal bridging going on. Internal wall going straight to strip foundation. I would add a strip of thermolite (or similar) blocks to straddle the insulation. Same on the internal skin of outside walls. The first block of the internal skin do that in thermolite.

Not sure matters for radiators or UFH. You adapt the WC curve to keep rooms at the temperature you want or need. So you set the balance at flow temperature point within a curve, dT will vary slightly with flow temperature, but the output is varied with difference in flow temp. Every house, every heat pump will react differently, you just fine tune the curve to suit.

That is almost always the case. But if that was part of the decision process, you would buy or do nothing. In some cases that may be the best option. My decision was easy, I'm earning, won't be earning as much in a couple of years and would like cheaper ongoing bills would there is less income. For less than the price of a holiday, I have cheaper electric bills for the foreseeable future. We pay less each month compared to no battery. When the battery fails we will replace with a newer, cheaper technology. Just like a computer.

No real difference from any other heat source. Heat Geek has a write up on several options.

Not really sure, but for it made things easier for me, I did the insulation and UFH and the ground workers did the floor, and had no corners to mess with. It was also easy to get hold of. We were building the walls this time of year, without bringing it all to doorway level, I would have been waring waders. One disadvantage of lots of insulation in a floor - it gets wet then it freezes overnight, and stays frozen for ages.

I did our differently to anyone else, I have seen. I did the floor insulation, UFH and then 100mm fibre reinforced concrete, prior to any walls going up. Way easier, then the cost is concrete m3 prices, we needed a 36m concrete pump lorry also, and 2.5 lorries worth of concrete.

As a way of illustration, this is our house with MVHR and our insulated summer house. The summer house has a single dMEV fan and it's heated, but temp is allowed to move about much more than the house. As you will see both building follow each other quite closely. The graph is year to date. Only time you have elevated humidity is in the summer, but it's hot not an issue.

Think I would be more concerned about winter, than summer. If summer bypass is on its likely your loft would be unbearably hot. Any condensation would vapourise.

Nice discussion but isn't duct supposed have a vapour barrier also? So any type of insulation is fine. Stuff like Climaflex is closed cell so additional vapour barriers are not needed.

Our office (designated as a store on the plans), is small, no windows, no heating, the hall it's attached too has no real heating just pipes to rooms passing through. I have extract terminal in there, so it's pulling air from elsewhere continuously. Within 10 mins of being in there it's nudging 21. In the summer it's the coolest room in the house.

Not really what I was saying. By branch I mean simply tee off to the user in the wet room. So central manifold, one leg goes to bathroom, within bathroom, that single pipe tees off to shower, bath, sink etc. dump the idea of lots of local manifolds. You are making issues by complex design, then making a hot water circulation system way to complex to compensate.

Nor me, I just flick the light switch, as required. Seems to be plenty of used control4 stuff on eBay. Not sure if that's a good or bad sign.

My floor area is twice yours I have 7 loops of UFH pipe on a manifold. A heat pump outside and not much else. In house is silent as there is nothing going on in the house. The other bits are a diverter valve and a single thermostat. Everything in the floor and manifold cost about £800, thermostat cost £60. IR UFH kits seem to be about £500 for 20m², so our house would be about £5k, instead of £860. Admittedly you need another heat source to drive a wet system. But even without a grant a Panasonic heat pump is about £2.5k. So not far off half the price.

Not sure if what I wrote wasn't clear or misread. The distance isn't a concern. By balance I mean how well matched the flow rate between in flow and extract.

How much! Didn't realise they were that stupid expensive. 210L direct cylinder £500 and charge with heat for 10 years free on E7, or about 6 years on standard rate, for the same price as it cost just to buy the Mixergy unit. Why would you bother. Could do the maths on payback, but would longer than the heat pump would last.