JohnMo

You either accept the cost and the same for the next quarter, or speak to the contractor to resolve or agree how or who will foot the bill. What in your contract?

I'm keeping it super simple. Slabs on concrete, 175x45 timber upstand, spaced 10mm off the slab, DPM inside and up the wall level, taped to DPC. Inside 100mm PIR, 11mm x2. OSB glued and screwed (floating on PIR), 50mm battens (screwed to OSB at 40pmm centres) and 50mm polystyrene UFH grooved insulation panel at 115mm centres, between the battens. Timber floor to battens. Building will be 70mm logs, with breather membrane inside, fully tapped to walls and all joints, with an independent 65mm stud wall inside spaced 25mm from outer walls (not attached to walls or roof), with 90mm Frametherm 32 insulation vapour control layer, airtight glued to OSB in floor and the multifoil in the roof, them plasterboard. Ventilation will be dMEV fan operating on humidity and PIV sensor, with back flow damper. Replace the timber for your blockwork on a simple strip foundation, or concrete pad. Surround building with gravel to stop splashing of rain water. Roof I'm actually going to use multi foil and PIR, as below but with 100mm PIR. I need a vapour protection layer, so thought use multi foil the way it's supposed to be with the correct air gaps. If it adds to the insulation value great as it's added no more height than I wanted, if not, I have vapour/air tight layer and was only going to use 100mm PIR anyway.

But how would anyone know reading that thread in isolation?

This is what the Scottish regs state, pretty sure English will be similar Every dwelling should have some form of fixed heating system, or alternative that is capable of maintaining a temperature of 210C in at least 1 apartment and 180C elsewhere, when the outside temperature is minus 1 C. So if you have UFH on the ground floor only, should anyone ask, you would only really need to demonstrate that the UFH can meet the heating requirement of the whole house, (i.e. the number of kW required) with one room at 21 and the others at 18. Which should be pretty easy to do.

Mine is sat on dense concrete blocks. If the don't last I pity many houses built from them

That's a bit of jump from another thread, stating midea cause it when nothing has been proven and testing ongoing.

I would look at your boiler manual, it will contain all the rules with respect flue placement and window opening and vents, etc and distances. Use that guide to make sense of what you are proposing, to see if it works ok.

A G98 size PV array with an immersion diverter, there is next to nothing to export, so no feed in tariff adds up to value for money for the extra costs involved with MCS registration. If you have a big array and battery and you can selectively export at peak times and consume electric at off peak, that may be a different story. But not check to install. We have a smart meter, but are 4 miles from town and the smart meter can't find anything to communicate with, so is dumb. We couldn't play if we were MCS registered, as all the schemes require a working smart meter.

Typically the bigger the cylinder the more heat loss per day, the variables are energy rating and size

So if you have options go with X plan for the control scheme (do web search). This allows you run two different temperatures from the boiler, one for central heating, so you can go with weather compensation, running the boiler at much lower temps and get plenty of condensing. The other temp is just for heating the cylinder. Also specify a heat pump coil, circa 3m2. This will give good reheat times, future proof also. As you say if there is no solar available you end up heating a 300L instead of a small cylinder. This what I did. The cylinder for DHW is dedicated solar. The boiler is a combi, if the solar water is above 45 it flow from the cylinder direct to tap. Below 45 it is heated by the the combi boiler.

Where are you in the stage of renewing, what are you replacing? Are you replacing boiler radiators? Or just cylinder?

I got mine from insulation hub, with free delivery to Elgin - H+H Celcon Standard Aerated Concrete Blocks 3.6N. They got delivered by keyline Inverness, although they couldn't supply when I asked them a few weeks earlier.

Not entirely true, even heating a low immersion the heat will settle after a soon period at the top of the cylinder. Just get a custom built uvc specify 2 or 3 immersions, to give lots of flexibility but also include a 3m2 coil just in case you want an ASHP later. Then just use relays or similar so you PV diverter heats top middle and bottom immersion in that order. But why not look at cylinder with an heat pump in it, CoP of 3, better use of solar when it's available. Beaten to it by @ProDave

Like most things it all depends on how it's applied. If it's behind a vapour barrier to keep internal moisture out and has a breather membrane on the outside, and not spayed directly on the membrane you are getting there. Spraying in a ventilated roof space with out vapour barrier and suitable external membrane and closing off ventilation routes, you are asking for trouble.

Think they the biggest or one of the biggest manufacturer in the world for heat pumps. Make lots of units for other companies, look at Hitachi and Panasonic heat pumps and compare to midea, lots of similarity including the controller. Was number one on my list, until I stumbled across another make on eBay. Just search for midea ASHP on Google, lots of information manuals etc all available to download.

No Would give good summer output, next to nothing in winter, assuming 10 degree from horizontal. Yes Consider a PV to immersion diverter also. If you haven't used a digger before, they take a while to get the hang of, so allow for the learning curve in your hire time.

Understand if the pump cannot supply enough flow to manage the flow requirements it will supply the lowest head loss loops and ignore the high loss loops. Which maybe the case here. But a conflicting statement is And Also if all flows show 2.5 l/min, would suggest zero commissioning has taken place and the flow are not balanced. Big pump or 2 maybe needed for 16 x 2.5l/min

Plenty on here with no heating upstairs as @ProDave says I used electric towel rads in the bathrooms with wet UFH, if doing it again I would consider electric UFH under tiles in bathroom on a timer. Especially if it was not single storey. Not sure why UFH should be expensive. If well insulated 200mm centres should be fine (I'm on 300mm), one thermostat, no actuators, no buffer, run on weather compensation or fixed temp with a 0.1 hysterisis thermostat such as Computherm, job done. Not even convinced you need a mixer, if on a single zone with no rads, could use a pipe stat to protect against over temperature. But even so, a manifold and mixer from Ivar are good quality and change from £450. 1km of pipe £1000 with clips and euro cones.

Doable, good output in winter compared to angled, worse output in summer compared to angled. Go onto a website that lets you calculate the yield.

If you are buying anything with a dryer in it make sure it's a heat pump dryer. Way cheaper to run. Had several Miele appliances, they are usually super heavy compared to other brands, if you have stairs beware. My Miele washer and dryer lasted about 10 -12 years, call out charges to fix after that were super expensive, so expensive that I bought a cheaper brand for nearly the same cost. Samsung seem pretty good.

I bought a remote probe, thought it was a good idea at the time. Found in a box the other day - full of other good ideas at the time. Where I was going to install I removed the thermostat, didn't need it. Do you need them - no, unless you embed as a high temp cut off to protect a delicate floor covering.

Was the system ever commissioned by the plumber - or did he just install and walk away? First set all the thermostats so they are calling for heat. Check all actuators are open. Then reduce thermostat temp (one at a time) and which actuators close (after about 5 to 10 mins) mark the room on the actuator (s). Once you have rooms for each actuator, check if they match where you think they should be. Your pump from the heat pump/boiler may be just too small to cope with the flow to all your loops. Go through each loop and record the flow being recorded on the flow meter. Does your paperwork contain a pump curve? It will be a graph m3/h or litres/min on the bottom and pressure or m head on the vertical axis. You have a short run of pipe to the manifolds, but a lot of loops in the floor. The issue could be the amount of flow required?

Look like posts to hold up the middle of the upstairs floor, also coincides with similar squares around the outside walls.

Big windows on the north just loose heat, so consider reducing the size. Overheating from lots of South side windows likely most of the year. Not sure of the mixed size of windows in roof and solar panels looks messy, try to standardize the sizes. As @ProDave says stairs are wrong. Void is just a waste of space, having your kitchen connected to also seems like a bad thing, fire, smells etc

So it looks like the post is inline with the outer skin of the building. So outside the thermal envelope. So not a cold bridge. Just looks a bit odd. So you need to infill, could you not just form a short return with brick block and cavity insulation, use a cavity closures on both sides insert window/door.