JohnMo

I used these inside and out, used hundreds, almost zero issues https://mkm.com/product/47mm-x-50mm-rough-sawn-carcassing-green-treated-t001663 These wood screws https://www.screwfix.com/p/reisser-cutter-tub-pz-countersunk-high-performance-woodscrews-5mm-x-100mm-250-pack/734pv

New invention, we bought ours about 15 years ago.

Not sure if you house layout, but could you add a dMEV fan (high up on an internal wall to push the heat from your hot room to hall way etc.

That's sad, for you, a heat pump dryer is a wonderful thing. Nice soft clothes and towels and next to no energy to do it.

You can get it from Amazon, RS Components, just choose the correct thickness. I choose RS Components so I get a known quality.

Couple of comments - because I can't help myself. 1. You have all loops transiting via what I assume is a hallway, then an additional 3 loops dedicated to the hallway. Deleted the dedicated loops and spread the pipes transiting through halls to provide hall heating. 2. Low temp heating will perform just as well with either spiral or serpentine. 3. Design is done on the premise of zoned heating, using a thermostat to control each area. Bit like adding the largest radiator you can fit on a wall in each room. As it is the floor array isn't designed for room heat loss, so balancing the heating will be battle. 3. Your pantry wants to be cold, I would keep all pipes well away from there by at least 300mm. 4. Assume your manifold is in or close to the utility, with all the loops transiting through that area, it will always be hot in heating season, you do not need a dedicated loop there. You will also need to think about adding insulation to pipes to prevent overheating. So 9mm insulation for the first 2m of each loop or run in 20mm conduit to thermally disconnect from screed for the first couple of meters. 5. Drawing by something selling products, not heating design. It isn't a heating design.

A lot of heat generators in a small area, the 16 loops if not insulated, would make the room hot, battery, inverter and cylinder will all add to it. Summer will be hot, running cooling via UFH should offset the heat some what.

I did plenty of testing. On a light use day a big hysterisis may mean your whole cylinder drops well below a usable temp. A normal use day it may be fine, but suspect you will have difficulty conversations with the other half, when the shower is like warm at best. So be ready for your head on a plate

If you use thin battens they will split, but there are screws and screws. Using self drilling screws makes a big difference, 50mm battens makes things better also

That's pretty normal Maybe not the best tariff for winter, Cosy may be better. Fill up at 15p/kWh You may actually make a loss in real terms if you are paying to charge and then discharging with round trip losses. Not sure about that, its more about being on the correct tariff. My electric cost to buy is currently 15p, excess PV I get 15p. I never charge battery to get paid for discharging only, only export excess energy from PV.

Why do you need a floor sensor for that? A room sensor does that anyway. If a room sensor breaks its an easy job to replace, not so sure about a floor sensor.

For the information it gives, would not bother. Certainly no need for cooling as your plumbers says. Pump at 17 degs, humidity will never be an issue - ever. I did short bursts at 12, with zero issue. Heat pump off, circulation pump on, will tell you way more than the odd probe in the floor, you can see solar gain and chart floor temperature drops and rise rates for heat and cool. Generally if you need more than a manifold and possibly a single thermostat (if the heat pump controller doesn't do that function) you are over thinking it. The thermostat should do heat and cool with in build humidity sensing. Humidity sensing is belt and braces for cooling and serve as as safety cut out off, if you or someone has been messing with controller

I would keep it simple and not bother with the complexity, for the small gains if any you would have.

Area is small for use as a heat source, it's expensive, in summer house over heat would charge ground, but only if you had no insulation. Big risk of freeze if you strip too much heat. So no.

The 150m² multiple zones I covered with a thermostat in hall and another in ensuite controlling a towel radiator (direct electric). Use the thermostat to trip the ASHP off, if I have the fire on in winter and for summer cooling. The rest is cover by 5.20b and 5.22a. High thermal mass buffering via thick screed floor and a thermostat in a room served by the heating circuit, in my case the hall. But I have a temperature sensor in each room, most are not generally used except for monitoring temperature. They are useful to understand what is happening, how your system performs, system balancing etc.

I use Rye Oils, cedar oil, one single coat lasts a couple of years, now done two coats and 5 years in and is due a coat before summer.

If you have access to the settings, they change how slowly or quickly the heat pump responds to change. Useful for some matching of water volume and/or heating system and rate of change to things like return temperature. So for fan coils you can speed things up and thick screed floors slow the whole response down. It acts like a stiff damper in one direction and weak damper in another.

If they cannot quote for a new build with good plans zero hope for a normal house, with no plans. Just cut out the middle man, buy yourself, then claim the vat back. So far finding direct cylinder heating via immersion for domestic hot water isn't that expensive, so a direct immersion cylinder is about £500 compared to £1500 for a heat pump one. Then get as small a heat pump, as your heat loss allows. Direct couple ASHP to your heating system. Super simple install, just two pipes.

I did Durisol ICF, used ready mix and a pump lorry, me, my assistant, ready mix lorry driver and pump lorry driver, was the full team. Someone else near me did the full pour via a mixing hopper and Tele handler all on his own, mixed it, poured it. So you don't need a full team, makes life easier and faster. Durisol (now Ecobrix) are easy to fill you are only filling 5.5 rows deep at a time. No special equipment needed just OSB support patches are cut joints and corners, so very DIY friendly. Concrete pump (36m boom) was £560 for 8 hrs. I did my build during COVID restrictions, which included the Durisol training centres being closed, so I had the build manual to rely on. Just followed the steps laid out in the manual and zero issues. Note: I like to read manuals, many people don't, Ecobrix manual is very comprehensive.

Aren't these a bit - yes they work great at bring in stable air temperatures, but can also bring all sorts of pathogens and bad stuff over time, so not the be all, end all solution? Plus you definitely need forced mechanical ventilation.

We have had several weeks at -9 over the last few years, no ore heat no ill effects. Our just winds back the incoming fan for a few minutes then back to speed repeat, to ward off frost issues. Cannot feel or heat anything.

Really would not bother, run hot and cold to manifolds central in the house and out to each wet room from there. If you are concerned about distance and time to get warm water, add a secondary loop and pump or simpler run 10mm pipe to sinks. Hot water will be there pretty quickly 40m of 10mm Hep2O only holds a couple of litres. If you need more than 40m you must have a HUGE house

Using your phone that detail doesn't pop up, you have to look at the profile, and many don’t bother adding that detail. In that case just go Duco, they seem well thought out bits of kit

Think in general it's a lot of smoke and mirrors and up selling stuff that really doesn't matter. Generally when set up to building regs flow rates you are over ventilating anyway. So a small drop in flow makes no difference. Do you need enthalpy heat exchangers in UK climate, not really. Makes - Titon HRV, I have two units, both are performing well. UK technical support if you need it. UK made. Also rebadged by Beam https://store.beamcentralsystems.com/collections/heat-recovery-ventilation-mvhr-units

No. Overshoot is shut off hysterisis, it's tripping out because it cannot shift the heat fast enough, or in other words the house doesn't need the amount of kW being put out by the boiler. Once the boiler hits a predetermined number if degrees over target flow temperature it will trip. A low loss header, just provides hydraulic seperation between boiler and heating system. If not designed correctly adds distortion to system, so boiler flow temperature is higher and radiators see a lower flow temperature. Well designed it isn't going to fix your issue. It's not a magic bullet and generally I would avoid. The thing your seeing is indicative of a boiler that is oversized, for the heat demand and cannot modulate down far enough.