JohnMo

No issue that's what I did. Take the return pipe to the furthest outlet, pump (suitable for potable water), check valve, and back to cylinder.

Why not look at a different company, or eBay and get the local plumber / electrician to install? May not get the grants if you buy on eBay, but could leave money in pocket now for other things.

Way too many lights, you'll need your sun glasses on before you go to bed. We have 4x shallow 80mm spots, a central pendant and 5A sockets by the bedroom

Similar to above, 200mm PIR, an additional polythene layer, UFH pipes, but 100mm concrete floor. We did the complete floor, insulation, UFH and top 100mm prior to walls. Found it easier that way.

Report worth a read on ventilation performance. Atamate_SDAR+Paper+2019+(1).pdf

I forgot about the slamming doors now you mention it.

I used Outsourced Energy for all my UFH had no issues. My bits came to about £900 for 190m2. (Excluding auto balancing actuators) A 2 port valve can be bought from anywhere, I bought one from Screwfix. Get Salus auto balancing actuators, make commissioning easy. Would expect a plumber for a couple of days, should be the cost to install.

Supporting guidance is a good place to look https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.gov.scot/binaries/content/documents/govscot/publications/advice-and-guidance/2017/11/building-standards-domestic-ventilation-supporting-guidance/documents/building-standards-domestic-ventilation-supporting-guidance-version-2.1-november-2017/building-standards-domestic-ventilation-supporting-guidance-version-2.1-november-2017/govscot%3Adocument/Building%2Bstandards%2Bdomestic%2Bventilation%2Bguidance%252C%2BNovember%2B2017.pdf&ved=2ahUKEwi157bV26_1AhWFiVwKHYYyA_gQFnoECAkQAQ&usg=AOvVaw15vStB1by3VrENg1Nc3XWy

MEV and dMEV are not allowed according to building regs if tighter than 3m3/m2. So balanced supply and extract with or without heat recovery is the only option left.

And all that ProDave just said.

If your air tightness is less than 3ACH then in Scotland you have no option. But great to live with, you put a toilet/ bathroom light on and silence, 3 month on I still still like it. A well designed system is the best part silent and in the background.

Efficiency is all to do with area and how much electricity is generated from that area. A 100% efficiency panel (if they existed) is just smaller.

I bought mine in a pre first lockdown sale, so my cost isn't real world cost, plus it came with all the roof integrated bits. Their site still has the various packages on, so worth a look.

We have washable carbon filters as well as the grease filters

That does not fill me with confidence

Everything ProDave says Shop around, prices vary, I got a package with 10 X 310w panels, all the other bits to make the system work from ITS Technologies. Plus get an immersion diverter.

There are 2 phase of cladding, the first phase was completed at beginning of the summer (gable and right of gable) and second phase (left of gable) about two weeks ago. Will be using Osmo UV protection, so hopefully 6 to 10 year between recoats

Ground slab should be giving you a good u value circa 0.1, get that put down in 2 layers with staggered joints, with all gaps foamed, top layer tapped. It will need a polythene sheet over the PIR and under the UFH pipes. The UFH pipes can be stapled to PIR through the polythene. Wall I try to improve u values if you can. Your new walls could you use thermolite blocks for one of the skins? Also the cavity with Celotex Thermaclass may be better with blown insulation or in Rockwool or similar as it's easier to construct (brickies likely to make to a mess of it). Not a huge fan of dot and dab. I did battons, and dry lined, but if you are plastering on top of plasterboard, why not just plaster the walls, you will get less air leakage overall.

I will possibly use screw piles on an out building in our wood, but not on a house that could be there for a century or more

Scottish larch, which I still have treat with a UV protection

Do a search on the internet for £100k house builds. That will give you an idea of spec. When upscaled to your house. £200k will give you modest well insulated house, but you will have to very careful on spec and make sure you spend the money wisely. What ever the architect says it will cost, take with a very large pinch of salt.

So if it's not windy, you don't have trickle vents - you don't have ventilation. Back to basic - open the windows, get a fan in the bathrooms. The average person looses between half to one litre of water per day just by breathing. If you don't ventilate you end up with damp house - you have a damp house. Your problem was being masked by open fireplaces.

When we doing our house I asked the architect about screw in piles and firmly told they would be expected to last the life of the building, so would be rejected by the council.

Here is ours.

Would it be be easier you use a sheet of toilet roll, place it near the mvhr inlet/outlet terminal, if stays in place its an extract, if it blown off it's a supply terminal. Cut and paste from passivhaus magazine, which make me wonder if you are just chasing your tail, with a dehumidifier, with the enthalpy heat exchanger? "Vaisey points out that on the other hand, if the relative humidity internally is too low, it can lead to dry skin, itchy eyes, and a dry nose and throat, creating a very uncomfortable environment for the occupants. It is suggested that the ideal level of relative humidity in a home is between 40% and 60%. The major sources of moisture inside the home are the occupants, cooking, showering and plants. When an MVHR system without an enthalpy heat exchanger is used, that moisture is lost to the outside — all that is transferred to the incoming air is heat. These systems also remove moisture from incoming air. However, the Flair 325 comes with an optional enthalpy heat exchanger. This works by allowing water vapour from the extracted internal air to transfer to the incoming air, raising the relative humidity. The quantity of moisture that is transferred depends on the relative humidity of the indoor and outdoor air and may run to about 60%. This is particularly useful with cold, dry alpine environments, with low levels of relative humidity. The enthalpy heat exchanger also recovers both thermal and latent energy from the extracted internal air, energy which would ordinarily have been lost to the atmosphere. “The average relative humidity in the UK is between lows of 70% and highs of 90% which is considered high, suggesting humidity recovery is not that big an issue in the UK,” Vaisey says." Would it be worth getting hold of a thermal camera, to see if you have local cold spots? Any water pipes in the wall close too or above where you have condensation? We had pressure tested our pipes, and had a drip every hour or so in service, took a while to find the issue.