ProDave

The immediate thing on that photo of the manifold is the numbers on the actuators are not matching the writing on the manifold You need someone to check that the actuators are really all in the correct place, otherwise you may have the actuator for one room controlled by a different thermostat.

The fact that much of what you say is sadly a symptom of "over burdened with silly rules" If the environmental / wildlife rules were simple, cheap and logical everybody, including farmers, would abide by them and wildlife would be better for it. Put too many stupid, over expensive, over time consuming and bureaucratic rules and a percentage will do as your farmers and the result is "what wildlife, there is nothing in this stinking pond" But the people that make the rules cannot see this is happening and their rules ARE the problem. We were lucky here that there were never any wildlife hoops to jump through, in spite of having a burn running through the site, and I know there are bats here, you see them flying about at dusk. The result of no silly rules is we just got on with is sympathetically. We did not harm the burn but neither did we need any tests, rules or barriers to ensure we did not harm it. There were no buildings on our site so the bats were not living there so we did not need a survey to tell us there were no bats put in danger. We just got on with it. We did not need someone to tell me there was a root protection zone around a tree and put a barrier to show it, we just knew not to undermine the roots of a tree. The trees are still there without a survey or silly rules to protect them.

For those reading (too late for the OP I am afraid) once you have your perfect line painted on the ground, you set up "profiles" around the site, far enough back to not be bothered by the digger, and these mark the lines you want to achieve. So once the digger gets busy you can check you are digging in the right place with a laser or even a simple string line between your profiles.

As above. Unless you have a gable wall full of glass, your view will be restricted by window positioning. Are you building TF or brick and block? Once foundations are in up to slab level, you might want then to check all window positions are correct and see if you need to move or re size some windows to maximise views.

Some of us (cough) run the MVHR at a slightly lower rate than building regs require, based on the fact the house has fewer occupants than building regs would count for the number of bedrooms. This makes it totally silent in all rooms and we still get lovely fresh air and no condensation or mould. Mine is also a basic unit and the only user controls we have are a timed boost activated with a button on the landing that we use when showering, that puts it into fastest speed for your chosen time period when showering. and another timed boost button in the kitchen that runs it at an intermediate speed while cooking.

So I must be the only one that used an old chisel to chip away the proud bits of plaster to allow my skirting to fit nicely, rather than complain about it? My take on plasterers, most concentrate on getting 99% of the wall flat and smooth, and don't or can't attend to all the detail like some of the edges and around electrical boxes. They leave that for the decorator to sort out. (but the plasterer that filled the electrical back boxes one one job deserved the sack)

I am in that group, but will compromise in that we already have one hybrid, and that will no doubt at some point get replaced with an EV. But we will retain one ICE car for the stuff that is beyond the ability of an EV. The good thing being the ICE car will not be doing much mileage in that mix.

I hope it is a modern LED lightweight 40" tv not my prehistoric (takes 2 to lift it) plasma!!!!!

So 14500kWh of heat is going to need about 4833 kWh of electricity, and at about 33p per kWh at the moment that is going to cost you about £1600 per year. As most of that will be in the winter 6 months, that will average £265 per month in the winter with more of that in the coldest months and less in the shoulder months. How are your actual bills comparing to that prediction so far? Hopefully like mine, the EPC over estimated the heating and my actual bills are lower.

One or 2 of the split aircon units would do the job, and give you the advantage of being a heat pump so roughly for every 1kWh of electricity you use, you will get about 3kWh of heat. If they are all on the same side of the house, you can buy ones that have just one outside unit that feeds to a number of inside units making it both cheaper and neater. If the house was built with the 2.4kW duct heater as the only heating source, one would hope that means it has been built very well insulated so it only needs a small heat input.

That shows the heat recovery is working. If the heat recovery was not working then the air being blown into the room would be a LOT lower than 18 degrees at the moment due to the very cold weather we have at the moment. The incoming air is never going to be as warm as the house temperature when it is cold, as the heat recovery is not 100% efficient but is sounds like it is quite close so doing the best it can.

So are you actually saying the room temperature on the display can be say 1 degree higher than the set point, and it is still showing the wiggly line "heating" symbol on the thermostat?

Can you explain the context of this picture? Is it the right way up? If so most of your pipe loops go UP from the manifold. That is not normal. Usually the manifold is on the wall and the pipes come out of the bottom and into the floor. Pipes going up will need provision for bleeding air out of them at the highest point, otherwise air will collect and you might get air locks which could explain some parts of the floor remaining cold.

Does it plug into a PCB? If so it really has to be that exact size and shape. Or does it just mount somewhere and 4 separate wires with a female spade connector plug onto it? If so I would just be looking for any relay of the appropriate rating regardless of shape and size. Even if it is a PCB mount setup, it would be easy to make fly leads to connect to any relay. That relay looks very like automotive relays, have you looked at those?

So it can't possibly be frozen. Can you call a plumber?

Do you have a thermometer in any of the rooms? If the taps won;t open surely you would know if the room temperature was freezing? If you don't know already, find out now where your main stopcock is, in case you have to turn it off in a hurry if it is a frozen pipe that may have burst?

When it was 10 degrees, the delta (difference between inside and outside temperature) was about 10 degrees. Now the outside temperature is 0 degrees or lower, the delta has doubled, so you would expect the amount of heating to keep the same internal temperature to double. Mostly it is down to the insulation levels. We don't know how good or bad your house is, what insulation and air tightness levels etc? What is the ASPH flow temperature set to? What is the UFH temperature set to? Those are things you can adjust to try and make the ASHP run as efficient as possible. I assume you had an as built EPC issued, what energy rating did that achieve? What does that say about estimated heating energy use?

No I just pointed out that it is more obvious now than it would have been in the past. Sorry sometimes I am not very good with words.

I dislike the hidden agenda behind smart meters, but in this context I was just pointing out one of the "benefits" that you get to see high usage immediately so in this case this might be why so many are raising this issue at the moment. Yes I know that. That is why it annoys me when some installer has installed an ASHP in a sub optimal manner and given bad advice, resulting in higher running costs than if it had been installed better, and worse when they "sell" the system as being cheaper to run than the old heating system. And it annoys me when in some cases even recently built developer houses have cut corners are are still being built a lot worse than they need to be. There is also a lot of ignorance among the public, on another forum I was reading of someone that just bought a house with an ASHP and because of that, he expected low heating costs. When questioned a bit more, it was an old stone house with an EPC E. It should have been obvious that with such a poor EPC any heating system is going to use a lot of energy.

I would still give in to the inevitable. It is going to happen, so negotiate and make it happen on favourable terms to you.

I blame the smart meter. Years ago nobody would know it was using a lot for a few cold days, they might read the meter once a month, or very rarely and a few days high usage would just get lost. Now so many people have a smart meter's in home display cheerily telling them how much they use hour by hour, they start to panic.

I am surprised it carries on running having failed to defrost. That makes me thing it does not even know it needs to defrost? Sensor failure or miss placed?

A solution looking for a problem? What is wrong with an ASHP on the ground where you can service and maintain it? Do you really want to get the scaffold out each time it goes wrong? This test house they are building, it looks to be inside a commercial unit. How is that going to work? or is it a massive environmental chamber where they can simulate all sorts of different weather?

And there in a nutshell is half the problem. One lot says "you must do this" and the other lot says "oh no you can't"

Yes but the OP has a less than 1 year old new build. We would hope that is built better, but perhaps that is another can of worms?