JohnMo

Sounds like the heat is circulating, but not being absorbed very well. So not being transferred to the floor. I had a similar issue with an overlay system in theory should have performed great in practice was pretty similar to what you are seeing. Low dT and very poor output, for a given flow temperature.

Yes, full kitchen, 3 bathrooms, decking patio, solar, heating etc all floor coverings, basically house ready to use and passed final inspection.

No too many variables our plot is 2 acres in Scotland not comparable to London. Our ground work other than foundation, isn't included either. We are on the side of hill had to carve out a road etc. The point of a well designed self build, it isn't anything like a developer house, so price wise not comparable either.

If you do option A you need insulation above the outside wall insulation to join the wall to roof insulation - otherwise it will leak like a seize. But I would just do option B, but add a 50mm service void to the ceiling with a vapour airtight membrane on bottom of rafter and service batten below then normal plasterboard.

Are you sure you don't have an air lock? Do you have a call for heat? Is this from anything external?

There are 2 or 3 port designs. I use one between heating and DHW. They come up.on ebay from time time pretty cheap https://esbe.eu/group/products/diverting-valves/mba130

And a home owners manual

Why not just use a simple diverter. I would look to use a MoMo diverter these use a live signal to move valve between positions and then draw zero Watts once there at either end of the positions. Something like an ESBE MBA. Then upstream of valve have a pipe temp sensor set to switch at 20 degs, anything above 20 is assumed as heating and below is cooling. Use the sensor to switch between the two positions. Use something like this to do the switching - nice simple and cheap plus easy to replace. https://www.toolstation.com/corgi-pcs-dual-pipe-cylinder-thermostat/p68281?store=LJ&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gad_campaignid=17808658009&gbraid=0AAAAAD-vLcX0JQPMjDufZ6UOJnzMg2icv&gclid=Cj0KCQjw9obIBhCAARIsAGHm1mSOycvA4DBwLfJ2NQYEJQUeyqdHr4w7n_OiVbj7YKg3ZkM4cP9y4ikaAs_kEALw_wcB

Have a good read up on that, then you will change your mind and keep a few grand in your pocket. Its useless in the UK.

Normal wood shrinkage cracks - nothing to worry over.

Means I would double my money - 💰 in the bank. I built during COVID the most expensive time you could build. Very limited people allowed on site one trade at a time. Material in short supply and a sellers market. Really depends if your self builder or just paying a builder or where you sit anywhere in-between to the final bill for the build. As mentioned previously, spec and how you buy has a huge impact on costs, but overall how you source has biggest impact. I sourced everything for our build except the cables and fittings supplied by the electrician, and roof was an agreed fixed cost.

You airtightness after second fix for building control. You also need an as built SAP completed.

Wouldn't the constant temperature controller try to mix flows to get a required temp, so may stay at mid point especially between heat pump compressor running cycles? How does your heat pump change between heat and cool? Is it an external switch and dry contacts or software via the controller?

Don't get too hung up on it, if the are not massive. My Passivhaus certified Roof-Maker ones have a Uw of 1.0. I spent more effort to get a thermal bridge free install, thought that was way more important.

Grand designs this week was a single storey, would guess about 180m² came in at £500k. MBC kit, ASHP, good kitchen etc, but a pretty simple design. All work by others. So about £2700 per m². Ours lots of work done by myself with others where needed, about £1800 per m², but quite a complex design in comparison to the above. All depends on complexity, quality of finish etc. how long is my piece of string really. Less airtight, no MVHR, double glazed not triple grazed and way less glazing would have saved tens of thousands. Different kitchen and bathrooms could have added tens of thousands easily. Not adding 100m2 of elevated (structural) decking to the front of the house and glass balustrade again 10s of thousands could have been saved. Bit like asking how much does a new car cost - it depends on...

You would need all the receipts and make sure it's a new replacement policy. A company I worked for had a shipping container with tools in it, until one weekend the whole lot was emptied. Not a penny came back from the insurance. All sorts of exclusion clauses.

It's just a money printing exercise for insurance companies.

It's a sauna, so a cold only shower outside - job done. Or cold plunge pool?

I have mine in the wall and use coander nozzles to throw the air across the room. Used in 3 bedrooms, lounge and long hallway. Lounge two dots at extreme edge of the image by ceiling. Air comes out following ceiling and drops about 7m later. All heated to room temperature, so you don't feel any air movement.

Walk away that is way too small. I chose 90mm to limit number of runs and keep away from noise issues. Costs depend on quality of stuff installed and layout of house and ease of piping runs. I used coander supply nozzles to reduce duct runs but about 50m+. I found with some upfront planning and quite a bit of getting your head around stuff, quite straightforward in the end to self install.

I used their duct (90mm) and various terminals and connecting plenums (90 to 125mm) no issues. Also used the foam 150 and 125mm ducts, again no issues. Ubbink also connects with various other brands if you want to mix other companies components.

Poor sheep and cows. But than live in the same field as solar, a double use of the field.

Not sure you really save anything by not heating rooms, the unheated rooms just suck in the heat from other rooms, so net energy input really doesn't change. Would really try to move to a single zone per manifold, the loops in that manifold get balanced to get room temps you want. Having room sensors in each room allows you run all loops or none just by switching pump. So example, room 1 is targeting 20 and rooms 2,3 and 4 targets 20.5. if any room drops below there target all loops come online and later all go off. But better still balance the whole lot to run WC. If suitably balanced all should be ok. Issue I found was if you are shutting down loops you can run into the situation where only one zone is calling for heat and the boiler goes into meltdown, short cycling and all the gain just get burnt with excess gas consumption. Share your current boiler and mixer model/make?

Easiest analogy is car car anti freeze. You can mix manufacturer but not the chemical makeup up. Car antifreeze is easy, as it's colour coded, blue, orange etc. the colour determines the chemical makeup up. If you try to intermix chemical makeup you are asking for trouble.

And optimisers where they are likely to get periods of shade over part of the array. Or the shade bits on their own MTTP.