ProDave

You are tackling this the wrong way. If it is excess solar that you are mainly using, then set the immersion thermostat as high as it will go. If you set it lower, then when your tank reaches say 45 it will turn off and your surplus PV will be wasted. So let it just heat as much as it can while the sun is out, and if tomorrow is cloudy and not much sun, you will have plenty in the tank for another day. I would also question if this will actually work for you? Most solar PV diverters supply a pulsed or power limited feed to the immersion heater to match the amount of surplus solar PV. I would expect this smart thermostat will be expecting a continuous power feed to it in order to operate, so I would not guarantee it will work when connected to the output of a solar PV diverter.

It can be very variable. My building warrant was delayed several weeks while we tried to find an acceptable drainage solution, only solved when SEPA finally said why not discharge to the burn. But then when we installed the treatment plant, BC were notified and did not want to inspect any part of that. All they were interested in was inspecting and pressure testing the drain pipe leading from the house to the TP.

You WILL need to check building regs before you go ahead. And sorry I am not up to speed with English regs, but in Scotland, a treatment plant must be 5 metres from a building, 5 metres from a boundary and 10 metres from a watercourse and you WILL need a building warrant to fit one. If your front garden is only 5 metres wide I don't see it being allowed there even if it would physically fit. but you talk about your field, so why not run the foul waste pipe under your garden, under your drive and into your field where you should have plenty of room to fit the treatment plant there? A sketch of your site layout would help. If the company is suggesting something that may not meet building regs then choose a different company.

You need to be sure it will fit in the front garden allowing for all legal distances to buildings, boundaries etc, and you have permission from the EA to discharge to the ditch.

That is the very last one I would want. You don't want to be the person replacing a jammed gearbox in that, and neither does anybody else. So I guess it's go it alone, BUT that relies on you having enough of your own land to do that, access to that land to get a digger in, and access to somewhere to discharge it to. If you need consent from your neighbours for any of that, then it is going to get difficult.

I would go for a new shared system but make sure it is a treatment plant, NOT a septic tank, and choose one that works with an air blower to agitate the contents, not the sort with rotating mechanical parts.

I read that as 7336 total maximum heat loss, which seems high to me but is in line with what the MCS estimate says. I found similar calculations in my SAP were 2 to 3 times over the actual real world heat loss.

At 400mm centres you frame around the opening probably needing doubles on at least one side of the opening. Regarding C16 vs C24, I was building my decking frame recently and accidentally found if I ordered 6 metre lengths they were all C24

There is unlikely to be any damp proof membrane under the concrete of that sub floor, so it is probably just ground water. That is why under floor ventilation of that type of floor is so important, so check carefully all the air bricks are free, not blocked, and most importantly, not covered by external ground level that has been raised too high and is blocking them.

We have a frght mixture of upstairs ceiling heights. The whole roof structure is hung from ridge beams so all rooms could be vaulted right to the ridge if wanted. But we only did that with one room, which has a mezanine above the adjoining small bedroom. Landing and bathroom we did a normal 2.4 metre ceiling to give us a just about standing headroom bit of loft space. And the master bedroom we did with a 3M ceiling height still giving us a feeling of most of the available height, while giving a further bit of crawling height loft space access via a step up from the main loft. If you want smaller joists to preserve headroom why not fit more of them at 400mm centres or even closer? At 400mm centres I used just 12mm OSB as the loft flooring to preserve headroom.

What I learned in my first self build (ordinary insulation levels no mvhr) is heating in the hall, and definitely on the landing was not needed. As stated up the thread they are "rooms" with little external wall and borrowed heat from other rooms, and in short the UFH never came on in either the hall or landing. Second self build I did not waste the time and effort laying UFH pipe in either the hall or the landing.

Good news. Just be aware the cupboard it is in may well be lined with Asbestos cement board, so get that checked if you plan to modify the cupboard when it has gone.

Sounds a positive step, but the devil is in the detail and as we don't know that it's impossible to say if it will be any better. Lets hope so.

Welcome back. We obviously don't know the details of why you stopped. That is personal that you may or may not want to share. All I can say is be positive and flexible with your plans. It would be a huge wrench for me not to complete. In our case it was unforeseen financial circumstances that forced a re think, and our revised plan was a very much slower "build as you earn" build with us doing far more of the work that we expected to at the start, but we completed and are now comfortable in our new house, and the eventual sale of the old house that caused all our problems actually left us better off in the end than we ever expected. So chin up, formulate a plan B and move forward.

If you do a proper heat loss calculation, e.g use Jeremy's spreadsheet available on this forum, it calculates the ventilation heat loss properly. If the MCS calculation does not do that, then it is flawed. Why do we tolerate a system that specifies a heat pump size without calculating it properly?

I have a contrary view on plant rooms. There is a trend to put everything together in one plant room. But is that the best thing? Not always. It was brought home to me when I wired a friends house, a plumber, and his plant room contained all the usual things, the mvhr unit, the manifolds for the UFH. the consumer unit and the hot water tank. Shame was, this put the hot water tank at the diametric opposite corner of the house to the kitchen and main bathroom. I similarly had a "plant room" designated in the room above the adjoined garage. But as it evolved, the only thing in there is the mvhr unit, and a few of the heating controls and a pump. The rest of that room is now my workshop / office. The HW tank is in an airing cupboard in the corner of the spare bedroom, giving it the shortest hot water route to all the taps. The UFH manifold is in the utility room putting it central to all the UFH loops. The plumbing manifolds are under the floor under the bathroom with access through a ceiling hatch in the utility room below, optimised for shortest hot water pipe routes. Consumer unit is on the wall in the utility room for convenience. All network and AV gear is in the cupboard under the stairs optimum position for short AV cable runs to the 2 main televisions. It just made no sense whatsoever to try and put all this in one place.

I am so glad NOT to be a landlord any more.

On the 3 heat pump installs I have done for others, I recon 2 days for the plumber and electrician so calculate that at your local rate, plus parts. Assuming you are going to have wet UFH anyway and a hot water tank, it really comes down to difference in cost between a system boiler and tank, or an ASHP and tank. There is not much difference to install in a new build. Or will bur BUS grant subsidise installation of UFH on a new build as well as the ASHP?

Definitely something odd here. But we don't know the details of your "well insulated" house. For another comparison my 150 square metre house has a worst case heat loss of just over 2kW for the whole house when it's +20 inside and -10 outside (a realistic winter temperature here) and is heated fine with a 5kW ASHP. There is a spreadsheet available on this forum that if you care to try it and input all the details of the house will give a very accurate idea of heat loss. I found even the detailed full SAP with all those same details over estimated the heat loss by some margin. Also if you do have a heat loss of say 7kW, then you will need more than a 7kW ASHP otherwise it would have to spend all it's time 24/7 heating the house and would have no off time and no time to heat your hot water.

Usually loose terminals. There will be a lot of current through that for 7 hours a night for half the year. One of the reasons a regular EICR is a good idea, that would likely have been spotted before it actually failed like that. When I did a CU replacement for a house with that sort of big central storage heater, I specified an over size board, so the 50A rcbo for the big heater, could have a vacant space either side of it to aid cooling.

So glad you got it sorted, and a shame the first electrician turned out to be no good. At least you can carry on with the heating you have for the short term and have longer to plan a longer term replacement. Keep the details of today's electrician, now you have found one that knows what he is doing.

Bearing Boys have replied offering me this https://www.bearingboys.co.uk/Miniature-Bearings/6082Z-SKF-Shielded-Miniature-Ball-Bearing-8mm-x-22mm-x-7mm-131446-p They claim SKF are better than NSK I guess that has to be better than my unbranded ebay one?

Not much luck yet. Simply bearings and Bearing boys don't recognise 608Z1 I have found this that identifies my bearing but they look to be a wholesale supplier. https://en.tradebearings.com/608Z1_C3_E-817847.html And I don't trust Alibaba to supply a "genuine Japanese NSK bearing"

My cheap bearings arrived today and I have fitted one. I can now confirm the rear bearing on this motor is 8x22x7. I did not want to pull the old bearing off to measure the shaft size in case the bearing collapsed in so doing and I would have been left with the ASHP out of action until the replacement arrived, and measuring the shaft diameter when the end of the shaft is flush with the end of the bearing was less accurate, so I had ordered a 7mm and an 8mm bearing. The ASHP is now running with a quiet fan as before. Now I have the old bearing off, I can confirm It is an NSK 608Z1 All the writing on this rear bearing was on the side facing the motor armature so completely invisible until the bearing was off the shaft. Getting the old bearing off was not too difficult. I tried my smallest puller set, but that could not get into the limited space. I was mindful of the rotor being a permanent magnet and no doubt not very strong. Levering anything against that would no doubt end in a broken rotor. So I hunted around various tubs of odds and ends in the garage, and came up with the brass nut off a 28mm compression fitting, which passed over the bearing and rested on the steel core of the rotor not the magnet, and then a screwdriver under each side to gently ease the bearing off. I will now seek a better quality 8x22x7 608Z1 to have ready for when the cheap one fails.

I very much doubt they will pay less. A long time ago now, when I was looking for my first house, I saw a Victorian terrace house for sale. It was not in a village but just a row of houses out on their own, fronting right onto a busy road, no off road parking, the only parking was a public car park about 200 metres away. I looked up the details expecting it to be cheap because of the lack of parking and inconvenient location. My bubble was burst very quickly when I saw the silly money being asked, and presumably someone paid for it.