JohnMo

Have got a gas combi boiler. The thermal store DHW coil is in use all the time and has a temperature control valve prior to combi boiler. In winter I get slightly preheated water in to the combi, to up performance, to as good or better than summer performance. In summer, PV should heat water in thermal store. This removes or reduces the need for gas for DHW production. If the water flowing through the DHW coil is at or above the combi boiler DHW setpoint it flow straight through the boiler without additional heat being added. Boiler is designed to take preheated water.

My build was always going to have a cylinder, to use excess PV instead of export in the summer. So no loss of space in my case. But would not suit all builds.

Using thermal store as buffer, heating it to 40 degs, no issues with short cycling. Houses stays +/- 0.5 degs from thermostat setpoint. So happy enough.

Heating costs should be really low, what ever option you choose. Not sure an electric boiler and wet rads would be on my list. Disadvantages, expensive to run, plumbing. Need to offset capital cost over running cost. I/R Panel heater? Easy to install, thin, quick to operate / heat you. Or A2A Remember you will need ventilation, MVHR, dMEV, or normal extract fans.

"I would not be allowed to remove any of the supplied controls. I can bypass or suplement with as many "toys" as I like BUT if I stop waking up in the morning then the installed system has to be useable." But that's the point, the supplied control made the system work badly. Huge temperature over/under swing. Timers would have to set 12 hours offset from time I wanted things to happen. I have single thermostat in the hall (always on), which calls for heat, or shuts off heat. Bedroom thermostats to make temp lower than the rest of the house, set at 17/18, it works great, they are not allowed call for heat. Set at 19.5, I get a plus or minus 0.5 degree swing, whatever is happening outside. I have no need to mess with the mvhr settings, it just runs at a set speed 24/7, except when boost is on.

Calculate the the surface area of the building exposed to out air temp. If you take the average delta between inside and outside. Write it down. Take your gas consumption, you will need to remove a proportion for DHW heating based on number of people in house etc. Look up for details, but I think it could be about 4kW for 2.4 person house per day. Write it down. Divide the gas consumption kWh, number days then by 24. This give you a number kW you consume to heat house approx. Now divide the exposed area by kW. This will kW per M2., Divide by 1000 to give W/m2. Divide W/m2 by the delta T. This will give you and average U value (but will include ventilation losses, which should be quite small with MVHR). A U value is W/m2.K K is Kelvin. Kelvin is deg C plus 273. But as you would add 273 to internal and external temp, taking the number s as presented would be ok. If you get below 0.15 your ok, if above 0.2, take another look at the numbers especially the domestic hot water use.

Not sure if I right, but I put in a 1000mm square shower tray 20mm high., There a 10mm lip once tiled on floor. But the only shower door you can get (or could find) are fitted with an upstanding strip under the actual door about 50mm high. But is there wording in the regulations about providing a space for... accessibility shower or bath.

We used a normal manifold, spaced UFH pipes at 300mm centres and have the temperature for hot flow at 35 degrees. Easy - way less pipe in floor, comfortable, bog standard bits.

Have you looked at dMEV, easy to install, silent and runs all the time. Just need window vents open or specific wall vent to give good, draft free, cross flow ventilation, you could also include the kitchen in the scheme. No heat recovery though. Or dMVHR, with heat recovery worth reading up about.

We've had really good trades people. We took a punt on the first ones in, they did a great job. We asked the workers in house at the time to recommend different trades that were good to work with, went with recommendations of the trades people in for subsequent trades, without fault they have all been great.

I just used my thumb to push the staples in

You can't staple to EPS, hence EPS at the bottom. If you are splitting use 50mm PIR minimum. Otherwise your staples will pull out.

200mm of PIR would give you a u value of 0.1 or less. If you are using PIR, you can staple UFH piping directly to it. But if using a concrete screed, you need to include a thin plastic DPM above the aluminium on the PIR insulation, to stop a chemical reaction. Finish what ever depth above insulation with a screed of you choice.

say 4 degrees delta T below 30 degs (second post down)

From what I've seen it just ups or lowers flow to keep it the correct delta T

Mines at 300mm spacing, over 190m2. Lounge has two loops, the other rooms a single loop. Total 404m of floor tubing. Low energy house though. No issues, UFH flow temp at 35 degs. But closer spacing, can run cooler.

Neither are massively efficient, some websites say the vogue is now discontinued? Why ask for an A+ rated boiler for example an Atag iS is the same price as the lower cost one.

CO2, has record 24 hr average, current, peak in last 24 hrs

Mandatory in Scotland, has to be bedroom.

I like the word passive and keeping things simple, reliable and future proof. Smart is to much faffing about to get it working (been there, done it, won't bother again) so kept things as simple as possible on this house. MVHR, once commissioned, don't touch except for maintenance, if the toilet smells hit the boost switch, same for showering or in bath. Humidity controls work, but not reliably in our climate. No point in automation. Heating, one thermostat does the whole house. Although I have an extra in each bedroom to keep temperature lower than rest of house. CAT 5 cables in each room. Fire system Aico smoke, CO and heat alarms. Simple standalone indoor camera in living room. Manual light switches, they work a treat, silent in operation the lights go off/on when I want. PIR with manual override on outside lights. Manual start and temperature control on showers and bath filler, manual toilet flush.

They will open / close to achieve a delete T of 7, but I believe at low temps like you are speaking, the delta is maintained at 3 degrees. Not sure of the exact switch over point between 7 and 3 delta T.

All I will say is the Passivhaus Trust mvhr install guidance says "MVHR must not be run until post construction cleaning has been completed and commissioning of the system is to be undertaken."

Your house will remain at a high humidity for a quite a while, as the house dries out. So don't worry. We commissioned ours after the flooring went due to dust etc. Things to watch out for with the flooring, is the sub floor humidity. This may be too high to accept the new flooring. Your flooring supplier will have a means of measuring the floor humidity (takes about 24 hours). Even though our concrete floor had been down for a year, we still had high humidity and had to epoxy coat, where the wood flooring was going.

That makes sense

I have Grohe, but only because I got them as a job lot at bargain prices. They do come with a good first fix kit, second fix is a fairy simple screw together once tiling is complete. The first fix allows you flush and leak test prior to plastering or plasterboard