ProDave

It looks to me like several of the zone lights are light up a bit. they should be completely unlit. do you have a multimeter to measure the voltage coming out of the thermostats? I suspect there is a problem. What thermostats are they?

One RING final 32A 2.5mm serving all the kitchen sockets. Double pole isolator above worktop to feed spured socket to each of Dishwasher, Tumble dryer, Fridge freezer and boiler. One lighting circuit 6A 1mm to feed all ceiling and under unit lights. Radial 32A 6mm to hob via above worktop isolator Radial 32A 6mm to oven via above worktop isolator. Check with your chosen electrician that he really is happy for you to pull the cables for him to connect, he will no doubt want to agree cable routing with him and tell you the rules. Don't forget if a new water or gas service entered the extension to include a 10mm earth bonding cable.

Solve the heatmiser issue before fiddling with the dip switches. With all thermostats down you should have all the lights off except Power. When you turn any thermostat up, it's zone light should come on as should the Heat and Valve light. Turn that thermostat and the lights should go off again. Which bit of that does not operate like that?

And sell the "slightly used" ASHP on the market place on this site.

Unfortunately the BG man is right, they are supposed to inspect the flue and if the flue is inaccessible they can't pass it. the fact they have incorrectly passed it for 7 years won't hold much weight with the refusal now. So you are going to have to cut that hatch I am afraid.

I WISH that was a requirement for rental properties. I always make it so, but you would be surprised how many don't. I draw the line at a built in Fridge Freezer where the plug is similarly hidden, I then tell them as it's not "portable" it does not need PAT testing and will be covered by the EICR.

Mine is timber frame so different, but I would never want to go back to the old ways of plaster on the hard where you are committed to getting all your switches etc exactly right so early on and if you want to change or add something it's a messy horrible job. It's one of the things I liked when I moved to Scotland where most houses are timber frame, and end to the task of chasing wires into a solid wall.

Replacement actuators are readily available, here is just one random example https://www.ebay.co.uk/itm/Rotex-Actuator-Ufh-Sat-8-Actuator-for-Rmx-Rmv-175145/223886639408?epid=9036438063&hash=item3420af0130:g:tKQAAOSw-MpeMvIr TIP: Buy ones similar to that link where the part that screws onto the manifold is a metal ring. Avoid the ones where a plastic ring screws onto the manifold and the actuator then clips onto that plastic ring, they are imho rubbish.

Then if you are not seeing any voltage drop either it's a compressor issue. Is the cut off pressure set too high? Is the oil in the compressor okay?

My "best" farm one was main house rcd tripping. Traced it to a caravan lead plugged into a socket, out of the window across a yard. Half way across it joined to a second caravan lead eventually to the caravan that some farm hand was living in. The joint between the 2 leads was underwater in a puddle.

They would not normally, it was just an experiment I did as I like to know how things work.

Can you clarify WHAT is "tripping out"? Farm electrics are legendary, and not usually in a good way.

I like Click Mode. They are cheap price, but very well made, one of the best. I have never been bothered personally about a pair of honest fixing screws. you can put the plastic caps on to "hide" them but I rarely bother.

I would not over think it. I would connect your heat demand to thermostat 1 input and try it. If you find the ASHP turns on when the UFH is off and vice versa you will need to change DIP switch 2-1

Ah my pet hate, where I have to slide a washing machine out to get to the plug to pat test it. Then you find the kitchen floor was done after the WM went in so there is a step up,. and the floor is only cheap lino and liable to tear at any minute. Oh the joys.

My LG ASHP has a terminal for an ordinary room thermostat. When that is activated, the HP starts up in heating mode, with the heating water delivered at the temperature set for heating. It also has a terminal labelled "cooling" give that the same 240V from a cooling thermostat and the HP will start up in cooling mode delivering chilled water at whatever temperature it says in the setup. And by experiment if you activate both, cooling takes priority and it starts in cooling mode. That behaviour will vary from one make to another no doubt.

Which repointing the joint will not do, that will just draw attention to it and make them suspicious. The best thing for a surveyor is leave it alone so he can SEE the joint is old and there is no movement or cracking, and an explanation of how the building changed many years ago to leave a joint like that.

Does that mean a sale fell through because a survey stopped someone getting a mortgage?

One thing that would smarten it up and to a small extend "hide" the obvious joint is paint the end wall white to match the front. If the front is render, not just paint, then render the end wall would certainly hide the issues.

I don't think much of the pipework coming out of the tundish..........

Are you sure "demand control input" is what you want? I would have thought "room thermostat" was a more likely candidate, after all the heat demand from the UFH controller is like a global thermostat output. I don't know enough about the Ecodan to know the answer to that. You probably also have to change some settings to enable each of these inputs to work.

Is that "join" within your property or on the boundary with next door? Is that your front or back wall or end wall? Just trying to visualise better.

What is your typical annual usage of oil? that would let us work out you actual real world heating needs and see if an ASHP is viable on it's own.

I would love to know what happened there. the "join" ends 2/3 of the way up. Above that the bricks are bonded across properly. It's like a small building got extended to the side and over the top? How do you know it's going to be an issue in surveys if there is no sign of movement? Any attempt to cover it up would just be seen as trying to hide a fault.

That might get more complicated. My own LG heat pump deals with the immersion heater differently by having a "sanitary water controller" which is a posh name for a tin box containing a contactor that switches the immersion heater. yours has the switching built in. By far the simplest if you have not got it yet would be get an extra immersion heater fitted when you order your tank and keep them separate. Worst case you might have to do some switching to isolate the immersion from the ASHP for the solar PV diverter. Or do as I did take the view with mains water and an unvented tank you don't need to to legionairs cycles so disable that function and just use the immersion for the solar PV diverter.