ProDave

It's more complicated than that. Any occupant is expected to use some of the facilities in the main house, e.g. perhaps the kitchen, or even the bathroom. If it is fully self contained and has it's own kitchen and bathroom so they live completely independent, than it fails the "incidental" test.

Do you have the IR camera still? If so I would shut off all flow to all the loops, except the one that appears to be not heating, and then when it has had time to equalise, use the IR camera to see just where the heat from that loop is going to.

You will NEED power to each manifold as they each contain a circulating pump. It would be best if the feed to each manifold came from a central location so they can be turned on and off by a central heating time clock, possibly (as I have done) allowing different time settings for each floor. How is it plumbed? From the heat source you will want a motorised valve feeding each manifold. I like to put the motorised valve next to the manifold, but wherever it is, that is where the thermostat needs to connect to, so the thermostat can open and close the motorised valve and turn on and off the manifold pump. The call for heat contacts from each motorised valve will need to connect to the heat source to call for heat when any manifold is operating. you have some wiring to do.

New build house with a car port detached from the house that you want to turn into a self contained annex? Have you considered: Covenants or restrictions imposed by the developer? Planning permission? Building regulations? Those are required in sequence, and the latter, building regulations will tell you how to build it, if you get that far.

In this case, as it appears the owner of the building is a builder, and he is building an extension to his own property. You would have thought as a builder he would have done some checks on what was under the ground. And as he is the owner, you would think he was astute enough to have noticed what was on the deeds, plans and searches when he bought it. He does not sound like the widow who's husband bought the house 40 years ago. A "I know a friend of a neighbour of a relative...." type discussions often turn out to be closer to home than originally described. Is there more you want to tell us?

Locate the circulating pump and turn it up to a higher setting.

If the loop to the cold room is showing flow on it's flow meter then it won't be an air lock. Increase the flow on that loop as high as it will go (watch you don't unscrew the flow meter housing completely)

Do you see water flowing properly on the flow meters on the manifold?

Wet UFH upstairs can be done easily. If he is quoting £10K for upstairs UFH how does that compare to the downstairs cost? Many of us find in in a well insulated modern house you don't actually need any heating upstairs, or in any event a lot less heating than you need downstairs, so radiators might be fine even if not over sized if you don;t need much heat.

The new Scottish law that comes into effect next year are NOT building regulations. It is something dreamed up at Holyrood and apples to all houses, so most will be retro fit. Building regulations still apply to new builds and they are different, as are the smoke alarm requirements for rental properties.

Heaters over 2kW are generally expected to be on their own circuit so your water heater and induction hob are almost certainly already on their own circuit. Diversity takes care of the likelihood of everything running at the same time.

Madness. Wireless ones are generally £50 more than a fixed hard wired alarm. The bit of cable to connect them is WAY less than £50 and easy to fit in a new build (which is what yours is in effect) The only place for wireless is a retro fit where the amount of disruption to the building to hard wire it is too much.

What does your installer say?

If it's not delivered yet, change that OSB order for 2400 by 1200 metric. I really don't know why they still make it imperial size, but if you use that and set your stud spacing for that, it will not match the plasterboard, alternatively you will be cursing at trimming every sheet down to 1200 to make it work. And are you really paying £30 per sheet? Christ on a bike.

That will go into the top part of a telescopic P trap. But sink and a half usually have a more versatile single trap with a tee connection to take both wastes into one trap and both halves are usually telescopic. So buy a 1 1/2 inch telescopic P trap and swap the parts over, use that one with the fixed nut for your belfast sink, and the one that comes off the telescopic trap should go in the kitchen sink to replace the one you have borrowed. Sometimes it can be handy to have a box full of assorted drain fittings to do a bit of mixing and matching.

That lot adds up to a total of 4140W or 18 amps. At that power rating you could just put a 13A plug on each one and just plug it into a socket if they are in the right place?

You have permission for the dropped kerb. Say no more, and just get a contractor with a minor street works permit to make the dropped kerb for you.

My issue with the ones with non replacable lamps, is what happens in 5 years when one fails and identical replacements are not available? If you do go that route, buy plenty of spare fittings.

Or you can buy wireless relay modules. I use one for my portable convector heater dump load. Transmitter in the box with my Arduino and receiver in a 2G back box creating a wireless switched 2G socket.

The only LED failures I have had was several Philips LED Bayonet lights bulbs. considering they were a make I used to respect and were not cheap, very disappointing. I do NOT like the current trend to downlighters having non replacable lamps, and glad all of ours are GU10 fire rated fittings with LED lamps.

I actually find the Honeywell ones quite reliable. Agree the Drayton ones are pants. If you think 2 port valves are bad, you have obviously never had a system with a 3 port mid position valve.

Another sealant I use is Water Hawk Potable water jointing compound

I just love the low energy of an all LED lit house. LEss than 150W with every single light in the house on. I can remember when just a kitchen easily used twice that amount. Nothing fancy here, downlights in hall, utility kitchen and bathrooms, fancy light fittings in living room and dining room, and standard pendants and shades in bedrooms. Warm roof here so ceiling penetrations for downlights not an issue (I might have mentioned a warm roof was one of or best design choices) and with the advent of LED's my aversion to downlights has gone.

Has anyone done a heat loss calculation on your house yet? Ours needs just a little over 2kW when it's -10 outside and +20 inside. Based on last weeks heat pump consumption we are running at about 1kW heat input at the moment (averaged over the whole day, that does not mean it is on 24/7)

The ONLY thing these fancy internet connected thermostats offer is the ability to change the settings or turn it on and off from a remote location. e,g, if you go away for 2 weeks in winter, then a day or 2 before your return you can turn the heating back on. If you don't want that function then indeed they are a waste of money. To be honest it costs so little to heat our house, I would just leave it on while away.