ProDave

It is probably an electrician you want to check your system out, not a plumber. There are a number of ways to wire a heating system,buy typically the programmer an room thermostats will call for heat to the manifold control box, that little grey box that the UFH actuators connect to. When one or more of the UFH zones have been activated, that box will tell the motorised valve for the heating to open, and the feedback contacts from that will call for heat from the ASHP. But there can be a LOT of variations on that, many are heat pump specific. You you need an electrician capable of working out how it is wired (assuming there is little or no documentation) and then working out if all the bits are actually working properly.

The one thing missing is an automatic bypass valve that would need to go between the ASHP flow and return in the garage before the two motorised valves. I would be very wary of a plumber diagnosing an expensive PCB in a heat pump as the fault. That sounds too much like fault finding by substitution at the customers expense.

My first thought is do you really want a house that big? Not only is it big, but has some awkward shapes and is not "optimum" design in terms of build cost per square metre. If the planners want 1.5 storey / room in roof, then there is not much choice other than dormers, but I do much prefer dormers like the house you pictured above where the dormer roof slopes down to the main roof without those horrible vertical side cheeks that most people fit to dormers that are awkward to build and hard to detail insulation properly. Or what we opted for was big "gable end" dormers like above the garage on your picture above. Detail that with a roof hung from a big ridge beam, and you can pretty much get the whole of the upstairs space unencumbered by trusses etc and make good use of the space and have vaulted ceilings right up to the ridge.

Why did you leave the ASHP on while you were away? I assume you mean Eco Dan (not fan) there is a thread about these where some models seem to be using a lot of energy when on standby to keep a sump heater operating, figures of up to 200W have been mentioned which would be a little over 4kWh per day for effectively doing nothing other than heating outside. My house during a recent holday was using 8kWh per day. About 3kWh of that is the treatment plant and MVHR unit, the other 5kWh would have been Fridge / freezer and other stuff left on standby though things that were easy to turn off were.

No those are both expansion vessels, one for the heating circuit and one for the hot water tank. A buffer tank will be like a small hot water cylinder with some lagging and several pipes connected to it.

So it looks like there is no automatic bypass valve? One needs the be connected between flow and return as far from the ASHP as possible but before the motorised valves to ensure there is adequate flow all the time. The actuators on the manifold will take a couple of minutes to open when first demanded and the heat pump is not going to wait that long before it's minimum flow rate is achieved. If there is a buffer tank then ignore the above. Post a picture of all the tanks you have?

What me and @PeterW are saying is we can't see how the manifolds are connected. The "proper" way is each manifold has a temperature blending valve and it's own pump to circulate the water around those loops. It sounds like you don'thave these and one pump directly feeds both manifolds with no local manifold pump or blending valve? If that is the case then if say only one UFH loop is calling for heat, then the flow rate is going to be very restricted. There would normally be an automatic bypass valve so ensure a minimum flow, I can't see that in any of the existing pictures.

Still need zoomed out photos to see what is between the pipes and the manifolds, where all pumps are, what blending valves etc? We have little bits of the picture at the moment not the complete picture. The pictures are displaying in their native orientation. The device you are using to view them and post them probably has the helpful stupid auto rotate function turned on so you don't know they are upside down as your device corrects that and makes you think they are the right way up.

I was meaning a full view, to see what pumps, valves, actuators and blending valves you have on and around the manifold(s)

DHW and UFH will only ever operate one at a time, and it is a completely different water circuit for each, so it is quite possible is is not achieving the required flow rate when it is on UFH. Can you post a picture of your manifold(s)? I had a similar issue with my own ASHP (different make) and the only way to make sense of it was to install an in line flow meter so I could actually see the flow rate being achieved.

Swap for a decent 4WD like my Subaru. Very hard indeed to spin the wheels even on a steep wet smooth road. It really does need proper ice or snow to spin the wheels on a proper 4WD.

You have posted a link to a document on your computer (so inaccessible to us) rather than post it as an image. Without seeing the picture, an open sided log store the logs will get wet then the rain blows from that direction. Perhaps not much of an issue unless that is the prevailing wind direction.

It has USB sockets, so it WILL be consuming power all the time. What on earth do you need USB sockets in a bathroom for? what can you not manage for the time you are in there on battery power? Old school shaver sockets had a switch that only powered the isolating transformer when something was plugged in, so nothing plugged in would be totally silent and not consume any power.

My advice is test as you go. You don't want to be finding out right at the end there is a leak somewhere, but you don't have the faintest idea where. So each time I added a bit more to the drainage piping, I would test it again to ensure the new bit does not have a leak. BC witnessed 3 tests on mine, one for all the outside underground drain runs, one for the bulk of the in house pipes, but before most of the bathrooms were fitted (blanked off ends pipe runs) and one on completion with everything connected.

BC inspector just visited and I did the pressure test while he watched. I bought a drain test kit when we built the first house 19 years ago. The one I have came with 3 drain bungs, a manometer and a hand pump to pressurise the drains. They might sign off with a drain test by someone else and not witnessed by them but I would not know who that might be.

Wishful thinking. You are right, 5%

And if you get a TS trade account, that's 10% off. That and their lower threshold for free delivery means TS now get more of my business than screweys.

I have tried a few like 100, 111, 150 and they all say the number you have dialled has not been recognised.

I was wondering that. the new VOIP service will obviously not work during a power cut. I was going to unplug the old landline phones, but if there is a chance it may still work for an emergency call, I might leave a wired phone connected to it. Trouble is it is not as though you can make a test 999 call is it?

One little oddity left. The old landline is still active, as in it still has a dialing tone. Dialing 14707 it reports it's telephone number which is now a different number to what we had, but it won't make calls and dialing this new number from another phone says unobtainable. Is this normal? I expected it to just go dead with no dialing tone?

Obviously you are in Scotland. Officially you should not move in until you have a certificate of temporary habitation from building control. It is BC not planning that might stop you. The house has to be safe and habitable so it needs potable water, a working sewage system or connection to mains sewer, wind and water tight, working heating, basically safe and a functioning kitchen and bathroom. P.S your location stated would help ensure we all have the facts. There are differences between the different parts of the UK The council will want to know as they will want to collect council tax from you (if they are not already) but that is yet another department, neither planning nor building control.

Slowest setting that gives the required flow rates on the flow meters. Both quieter, and uses a little less electricity.

Turn off the stopcock and if the tap still flows, it can't be mains, it must be from the tap. Or simpler, do you hear the header tank refilling after you have run the tap? If so it is coming from the tank.

It's a fascinating subject that can take a lot of time to understand fully. I have still not got to the bottom of why our "non heating and non DHW heating" use exceeds the heating use, and like you it goes up in winter when logically that can only be more use of the (all LED) lighting. Is it worth a planning application for an ASHP so you can DIY install one? Or just do it and hope nobody bothers?

Just taking that pot off from just a roof ladder would frighten me.