ProDave

I am pretty sure the LG puts up a little symbol on it's control panel when the resistance heater comes on.

Yes there are less choices of switch type for intermediate, and it is hard to get an intermediate in a 2 or 3 gang switch.

Yes automatic changeover 2 cylinder setup. If the property still has a gas hob then make sure the vendor includes the gas bottles or you will be going and hiring a new pair. If no longer any gas appliences (e.g all electric now) and you don't intend having a gas hob it can be removed.

I would put my money on either the upstairs switch has failed, or one cable has come loose as the first place to look. If not there, the next switch in the chain which will be an intermediate switch, that may or may not be the one at the bottom of the stairs.

the Therma V does not switch itself off when it gets cold, it may switch on the resistance heater as well. That is very configurable. I have mine disabled so it is never used, but my HP is well within the total heating power requirement.

It's on a par with the toilet cisterns refilling with 4C water and just sitting there being warmed up by heat from the house.

My LG simply turns on the water pump periodically to keep the water outside above an undocumented lower limit. In fact there is really nothing documented about this (very poor) and I have not found any settings to adjust anything about this function. So it WILL expect water to flow when it wants it, from somewhere. It won't run a defrost cycle as the compressor and heat pump is not running. Rather than re invent the wheel, why not let e.g the LG heat pump turn on it's own internal 3kW electric heater if the heat pump is unable to maintain the set flow temperature demanded? It won't be the heat pump unable to function because it is too cold, the problem you might face is it can't get the flow temperature high enough if heating demand exceeds the heat it can provide.

Modern stoves have a limit on how far you can shut down the intake to meet modern limits. Some have a little crafty footnote that you can remove the stop if you really really want to close it down further.

Urban myth I think. I have just checked with the Ir thermometer, and no part of the stove or the single wall flue exiting the top, is any colder than any other part of the room, so any natural draught and heat loss through the stove is tiny. My intake duct is insulated as it passes through the wall then down under the floor. It does not get hot there, I used plastic ducting once it enters the wall and down.

Buy yourself a couple of these this one just as an example from https://www.ebay.co.uk/itm/275552493434?hash=item4028355f7a:g:g0AAAOSwbqRjfNZ7&amdata=enc%3AAQAHAAAAoDzqDZhBEFGC%2FD7CD3ceaM5Ahx%2F%2BVHlp%2F5jPJkZnKkIUMZ7t5wIkfNvL3IweWYNoCcy%2BsB2Jg%2BwnORTSXZT16neUElao%2FZH%2BUNiHO1hoCpI9JDsb3dzZYWLLM%2BF2Kv2sSzLF6LK8tn48TzWiDEApveIUqsnEawlfWhNFz8bidI1s8pC9kodv3v0ZTMHprJO%2FNSd03mKB9SQ9CILmQMYef0E%3D|tkp%3ABk9SR8CZyPbJYQ They have provision for fitting a water meter which you probably don't want so make sure they come with the blanking plug to go in when no meter is fitted.

With a lot of the self builds on here, by the time you have finished, most of the stuff you fitted at the start is out of warranty.

I would not pour the screed yet. While you have improved the cold feed situation, you still have the cold feed to other parts of the house buried in that same screed.

A fine tooth panel saw is easier to get a straight cut.

With a saw. What other options are you expecting?

Yes I believe the way forward is to halt the job, meet with your BC inspector yourself without the builder present to intimidate you, go round all the points this thread has highlighted with him and get him to evaluate them, and then provide you with a list of things that need correcting before the job progresses. Your builder won't be able to argue with that.

Only bought the business in 2023. Lack of due diligence, Or deliberate asset stripping exercise?

That is an allowable option, that is what we have. The discharge needs to be visible, above ground, at least 100mm above the ground, drain to somewhere that drains away (BC accepted ours discharging onto a French Drain) and covered with a cage.

The "Electrcian" needs to go and read BS7671, particularly the bit that deals with "Safe Zones" Most of that wiring is not in a safe zone. I am particularly intrigued by the green / yellow wire hanging down to where I think the island is going where the rising main is. I wonder what he intends that to do? Sadly the electricians work is down to the standard we have become used to on this job. We should have expected that having seen snippets of his work already.

Their offerings are here https://octopus.energy/get-a-heat-pump/ Standard install for £3K including the £5K grant. So I read that as the customer pays £3K, Octopus get £8K total. This bit is interesting: "Connects to most existing piping systems and high temperature radiators" I will be interested to see if they live up to expectations or not.

There is a LOT about that pipework that needs changing before you let the builders anywhere near it with screed. The massive failure on the D2 discharge pipe is ALL those sections of pipe have to run DOWNHILL from their discharge point to the tundish (and then downwards presumably via a trap to that soil pipe) You have at least 2 sections of pipe going up hill. There are also strict size limits which you don't appear to be abiding by. Whoever did that does not actually understand the unvented cylinder regs so who do you think is going to sign it off as compliant for building regs?

So it was you we passed walking up Cairn Gorm with a gheto blaster on his shoulder spoiling the peace and quite was it? I would describe that as a UPS rather than a "power station"

So in the UK, just how deep do you have to go to get useful geothermal?

I am more interested in what meaningful data you can get out of a £2 SIM, I assume £2 per month?

DNO don't seem interested in what DOES happen, just what COULD happen.

The most stupid (shows their lack of knowledge) comment was from the planner at my previous 1930's house who refused my planning for a detached garage. I had described the construction as "concrete block and rendered to match the house". The planning officer said to me "but it would still look like a prefabricated garage" and no amount of explaining would change her view that it was not a prefab building. It passed on appeal.