JohnMo

Possibly the worst of all things as far a cost to run and performance. 3 to 4 times the cost to run compared to a heat pump or gas. Low flow compared to gas combi. Would it be better to use E7 to heat a unvented cylinder for DHW, or a combined cylinder heat pump, basically the same price as gas or a third the cost if run on E7. Space heating with an all in one aircon/heat pump (no outside unit, just inlet outlet through wall), if you have UFH Willis heater's run on E7. Summer heating of DHW with solar either PV or/and thermal solar. That's my thoughts. If knew how our house performance a year before moving into it and wanted all electric. UFH with Willis heated on E7, combined cylinder (stainless or duplex) and heat pump, immersion diverter and solar thermal for shoulder months when PV performance is low for DHW.

Would have thought if it's structural, it would be graded C16 or C24, not bog standard CLS

We have UFH in bedrooms, (single storey building) the issue I have with it, is once it's on, it's on, no turning it off when you want to go to bed, so pretty much a waste of time. If we need the room warm we open the doors and within an hour it's the same temp as the rest of the house.

thermal lightweight aggregate, screed with EPS beads mixed into it.

Are you building a nuclear proof bunker? That's one thick floor. What are the rooms on the first floor? How well insulated is the house? What is on the ground floor for heating and insulation?

We didn't install in these places. Under beds. Under fitted bedroom furniture Under kitchen units. Store room. Under bathroom furniture. In hall or utility, as all other room piping passes through hall and utility.

Not sure why people take years to build a house, a weekend should do it. Few hundred pounds with kitchen and fire and woodcrete insulation.

13/14 for me glued to concrete. No issues so far. Just follow the recommendation of the manufacturer. UFH performs well. You are unlikely to sand, our last house looked great after 10 years.

Heat during the night on cheap rate, as well Insulation etc. Or ditch the UFH and install radiators

Joy of England, we can't get the warrant until structural engineering is completed.

Isn't it defined in your structural calculations what you should be doing?

We are not in the Highlands, but have an IV postcode, and still supplier want to rip us off. eBay is as bad. But if they don't give me a good deal on delivery, I just look elsewhere.

Screwfix supply everything, check pricing with them. BM will be giving the plumber a discount, which they won't want to disclose to you.

Long pipe runs mean, bigger pressure drops, which mean for a given flow rate the MVHR unit needs to work harder, so makes more noise. Consider 90mm if going semi flexible. You haven't mentioned what the piping is. There are several options. Semi flexible, comes with a plenum, this reduced cross talk between rooms, is easy to install. Other systems will require multiple attenuators/ silencers between rooms. If any quotes specify flexible duct, don't use them. High pressure drops, so not good.

Triton HRV, made in UK, good range of sizes and specs, good technical support, spares readily available, passivhaus certified if you need it.

Or use coanda effect supply valves to throw the air across the room. The air follows the ceiling for about 4 to 6m, then descends and comes back across the room and out the door.

Or use double sided tape to hold in place.

Wouldn't you just end up chasing your tail for ever, as things will change on a minute by minute basis. And still leak heat to atmosphere at its temperature? The better insulated the building the closer the OWT, will be to OAT and vise versa for poorly insulated. All confused if the sun is out.

The membrane is to stop the chemical reaction between the cement within the screed and the aluminium covering the insulation. The reaction produces hydrogen gas, which leads to bubbles in the finished floor.

Think you need a plume kit. https://www.screwfix.com/p/worcester-bosch-plume-management-kit/90277?tc=TA5&ds_kid=92700055281954502&ds_rl=1249404&gclid=CjwKCAiAgvKQBhBbEiwAaPQw3KCC9yBmYfLy6tsbGO7b6w2iKD9sluZDsnUZtVRKX-k3gFFPMnDiMRoCeYcQAvD_BwE&gclsrc=aw.ds

Photo taken just now, no sun, as just about to disappear, it is always red.

You may be over thinking it, I doubt you will really notice the difference in width once finished. Wester red cedar? Scottish Larch on ours - will be treating with cedar oil.

I would have thought the basics are 1. Simple manifold so you can flow balance, actuator of each loop, all wired to act as one, from single thermostat. A simple UFH wiring centre, that would manage the thermostat, actuators and pump, possibly a relay to manage the heater, using the wiring center CH signal. 2. Single simple thermostat, I'm using a Salus wq610rf, set to 0.25 hysteresis. £60. You can move it around the house to find the best location, before committing to holes in wall. 3. A mixing valve upstream of pump, to give you protection if the thermostat in the Willis heater fails. 4. Pre installed (spare) second heater, valved to be put online should the first unit fail.

Solar powered?

We parged before the wall plate went on. We used hybrid sealant on the the fixing that went through the wall plate, and a good fillet around the plate against the wall. We used blower proof liquid around the whole perimeter at floor/ wall interface. We screwed battens to the wall (ICF Woodcrete) and added hybrid sealant to the screws threads. Do you need vapour barrier on concrete blocks? We have it on the roof/ceiling, this is bonded to the parge coat at the top of the wall.