ProDave

What hearth and how laid?

You don't need internet for that. Our heating programmer has a "holiday mode" where you tell it the dates you are away and the heating is off for those days. We set the return day 1 day before we actually get back to give it time to heat up.

Even fully modulated down it would be too much heat for our house even at -10 outside

The point is, if you buy the kit and install yourself, it will probably still be cheaper without the grant, than getting the £5K grant and paying for an MCS install. A monoblock ASHP comes charged with gas and does not need an FGAS installer.

Possibly but I am sure before I have seen if you use a waterless trap you don't have a tundish. Anyone more knowledgeable care to comment?

More likely a pressure relief from an UVC could let off a lot of steam (literally) and it NEEDS an open vented stack for that to escape. A waterless trap won't allow it to vent. A 22mm copper pipe exiting the building seems the lesser of 2 evils compared to a vented 100mm drain stack.

What is the build standard of the rest of the house? i.e. standard, or all air tight membrane and service void? A cold loft is the hardest thing to detail as not only cracks like this want sealing, but EVERY penetration, every light fitting, everywhere cables drop down into a stud wall etc etc.

Why not post some pictures of the pipework and what connects where, it might give someone a clue.

We have dishwasher into the kitchen waste and washing machine into the utility waste. It is true, that when one empties, you hear the water running out of it and down the sink trap. I assume this is what @Nickfromwales refers to as "gurgling" When the appliance is not in use it makes no other noise. Personal preference if that noise bothers you, but if that noise bothers you then chances are just the noise of the appliance also bothers you. We have a dishwasher in the kitchen as that's the obvious place but I would regard it as a VERY backward step to have a washing machine there. That is what a utility room is for, tucked away so the noises of the stuff in there don't bother you.

The advantage of an ASHP bigger than needed for space heating, would be quicker DHW re heat times. But it would not be able to modulate down low enough for heating needs so would indeed be cycling more.

Different people do things in a different way, but typically on a cylinder with a WBS I would have two tank stats, one to turn the boiler off when it reaches set temperature, and a second one, set slightly higher, to turn the CH circulating pump on (regardless of programmer settings) when the tank starts getting too hot from stove input, to dump heat to the radiators.

Check the BOILER thermostat. If that is set below 75 degrees then you will NEVER get there from the boiler. Often boiler thermostats have no scale, just min to max and arbitrary units. Post a picture of the boiler and it's thermostat. The thermostat on the tank is probably * what turns off the boiler when the tank reaches the correct temperature when heated by yhe boiler. The thermostat on the pipe is probably on the flow from the stove to turn on the heating pump when the stove is producing heat. * Probably as dual feed tanks particularly involving a stove are more complicated as the stove is an unctontrolled heat source.

But following Brexit, can you just import a Spanish VAT paid item to the UK? Surely now the Spanish supplier would have to sell it ex VAT as it is leaving the EU and then you pay UK VAT on import (which you later claim back). That is probably why they are looking for a VAT registered agent to handle it?

Here would be an interesting experiment for someone with lots of time. Take a bit of ordinary t&e cable, load it to it's maximum rating and measure it's temperature (some form of probe attached to it) Then bury in in the middle of a load of EPC beads no more than 100mm wide (or whatever your cavity width is) and repeat the load test and see how hot it gets. Wiring regs talk about cables "in insulation" But there is a big difference between a cable enclosed in the middle of 300mm of rockwool and one enclised in the middle of 100mm or less of EPS beads. Yes you could derate a lot of the circuit breakers, but not on things like cooker or shower circuits. I think the issue is not overheating and increasing volt drop, but overheating and melting the cable. A rise of 50 degrees C would be very bad for PVC.

Sorry I am thick again I see the socket in your picture and the plug that has to go into it and see no reason it just won't plug in. Just what is in the way?

Remember the level entry requirements stipulate a flat area in front of the door, so a wooden ramp on top of that, would have to have that flat are first before it starts to slope. That is NOT a "level entry" door. If it was it would not have an external cill like that, just a threshold strip that floor inside and ramp outside tuck under.

Then I would NOT fill the cavity with any sort of insulation.

In the kitchen picture (with the loo roll mountain) what is the purpose of that illuminated recess under the worktop on the island?

I would have closed them with noggins where they crossed the outside wall, then insulate up to the noggins on the inside.

Forget the plasticiser issue. Nobody has yet mentioned the need to derate cables enclosed in insulation, so if you are not thinking of rewiring you might be. When you say cables in the cavity, do you just mean passing through? That is probably okay. Or do you mean cables dropped down the cavity and traveling long distances?

If they are typical G9 halogen lamps, you can get LED replacements, but a lot of the LED ones are largerthan the halogen lamps.

As above. I have worked on 2 "wet" properties. The last one was left empty in winter, a water pipe in loft burst and when it thawed emptied the contents of the water tank into a bedroom. Part of the ceiling came down and the floor was well soaked. The insurance surveyor thought it needed drastic action and the insurance paid to strip the whole property back to a bare shell, dry it for weeks with a dehumidifier then rebuild it. They got a virtually new house. I presume the insurance took the view that if you just repaired the obviously wet bits then in future years you could be looking at more problems lurking?

Presumably you will be rewiring so is it even relevant?

That one does look like a GU10, are you SURE the front does not unscrew, note some unscrew clockwise which seems "wrong"

Expecting another lockdown?