JohnMo

Have you installed the top level UFH piping?

On a smaller buffer, you get plenty of mixing between the flow and return which requires the heat pump to put slightly hotter water to compensate, so there is a cop hit with the four port plumbing. You also need an extra pump on the secondary side. You do not need a bypass with this arrangement as the buffer acts as one. The two port plumbing of buffer, mixing doesn't matter as there is no interaction between flow and return, so you may get better CoP. A bypass valve may be required, depending on how you arrange your zones. You don't need a secondary circulation pump as the circuit is now all primary. The buffer becomes a volumiser. Generally you are going to a lot of pumps running all the time if you are not careful with the design. At the moment you have ashp circ pump, secondary circuit pump, one pump per UFH manifold. On a 6 month heating season, that could be £200 running costs just for the circulation pumps.

So only guessing here. It could be it's learning and (really a bit of question) could it be struggling to reheat the 10 degree drop in one heating attempt? So it's starting to heat earlier. Heating to 55 isn't that good for CoP, a lot on here, heat to about 47-48, the you can set the hysterisis at 2 or 3 and heat pump has way less to do.

The best place to buy is eBay, they come up quite often, usually for a good price. Here is a manual, just replace boiler with electric inline heater. New FlowSmart Inst and serv instructions 2-12.pdf

PIR is a pain to install well, very easy to install badly between joists. So not sure I would go there. We added counter battens to increase depth to 350mm then did full fill with spray foam, Then double taped avcl over the whole lot, and glued to the walls. then 50mm battens and plasterboard. If you don't like that idea, go with something like Frametherm 32 between the joists, the underdraw with PIR etc. Whatever you do make sure water vapour cannot makes its way in there.

A slight left of field suggestion Very small cylinder say 50l. Heat to around 60 degrees via heat pump - cop of 2. Or via immersion and solar. Not a big cylinder with an outside diameter of 450mm dia and 600mm high. A cylinder such as an Alpha Flowsmart 50 has a DHW coil inside and has heating system water inside the cylinder. Have a thermostatic valve on the outlet of the DHW coil and set to about 30 degrees. This would then provide loads of preheated water to an inline electric heater. The lower heating requirements of decreased delta across the inline heater (no longer with an 8 deg inlet temp) will give a considerable flow increase or allow a smaller kW input for the same flow.

Fresh-R is one, but you can do it with a normal MVHR unit also. You could use something like a PIV supply nozzle connected to a standard MVHR as a single supply point. With extracts in wet rooms and where required transfer fans. The other thing to look at is coanda terminals, for supply and extract. They work by the velocity of the air sticking to a surface (ceilings), so you can have a supply one side of a room (even at a doorway or air exit point), air coming out of the nozzle will travel approx 4-6m then come down, travel back across the room, down the corridor to the nearest extract point. The air when it comes down is at room temperature, the air stream is wide so velocity is low, no draft. I have them in lounge and all bedrooms, duct lengths are shorter compared to a normal nozzle.

Really - you have put 2 years into it and now you want to knock it down and build from scratch. By the time you get planning and built another 2 years, if you get contractors in, 3 or more if you do lots yourself. How much heating energy do you think you will save to recover costs. So build cost £2k/m2, 100m2, is £200k to build, save £1k a year on heating (which you won't)- 200 years pay back. Get some decent contractors in and get it done. Money obviously not an issue, or you wouldn't be posting the question. Or is getting a passivhaus badge the important bit?

Living life on the edge. But its not as bad as looks really, more a 45 degree slope.

Take a look outside, where is ground level compared to your DPC? If it's not a 150mm below, that could be where the water is entering. Ours was pretty close to dpc for a while and we had similar.

I would look up and have a read on cascade MVHR. But also read up on condition based dMEV, where the inlet and inlet is humidity controlled only ventilating when required.

Ours ended up being done a year after the house was complete. Converted to 28mm copper before coming up the wall. Then core drilled 2x 50mm holes, placed copper tube central in the holes (slight upwards to allow self bleeding) and used expanding airtight foam to keep in place. And then sealed the ends at the wall with sealant. Then used external 19mm insulation.

Maybe not the best fencing option for the job at hand. Or change the shape of the fence line so you close to 90 degree angles. Or use round posts at the corners and just notch a flat at any angle you want.

I would ignore it all. You can't commission your MVHR without windows. Every new build is in the same situation if they install MVHR. No trickle vents and MVHR commissioning completed months or years after the windows go in. Building regs requires vents for a normal ventilation system, but these do not have to be in a window, they can be in the wall if you want. Yours is supplied via the room terminal from the MVHR.

If you want the best cut a roller, but you will need to cut the often, a rotary one is more forgiving. If you get a rotary one get one that mulches the grass, as long as the cut isn't huge all the grass cutting gets pushed back into the grass. I just need to find a decent one with all wheel drive for our slopes. The 2 wheel drive one is hard work.

That may be so, but still looks a bodge.

So to get the terminology correct you don't have vapour control layer in a floor, its a damp proof membrane. The UFH pipes are (or should be) well above the DPM, as you would not want to puncture it. You possibly need to get a design bottomed out for the floor before worrying about details of holding the UFH in place. That will fit together more naturally once the floor is designed.

I can see a few issues that look like they need addressing first. The screws going through the insulation will not support much for long, they all need washers to give some surface area. They also need to be taped over. The gap between the wall and insulation needs to be filled that would be with foam or glass wool. Wires supported on screws just looks wrong. The white cover over what I assume are cables is held in place with cable clips, that's a bodge.

With the duct and insulation you also get an air gap, which adds to the insulation as the outer duct/pipe is sealed at both ends, so you also get an unventilated cavity. When you look at the details of pre-made underground insulated pipe the insulation is not really that good and want loads of £ for it. Looking at Rauthermex 32+32/111mm DUO Pipe, you have 2 x 32mm pipe in a 111mm pipe, the insulation may be slightly better but it's not very thick. I have one 28mm pipe in a 110mm pipe the rest is insulation. So overall I think it's cheaper and better quality than the ore made stuff. The shed is also well insulated, basically pallets full filled with rockwool. Vapour control layer internal and breather membrane external.

The only concern with these units is do any of them move enough air around so you get a proper through flow of air, is it just moving a 6m volume of air in to and out of the house. Working on a dilution principle instead of an air exchange principle. Read up on cascade MVHR, this use a central supply or two, then extract in suitable location to get proper cross flow of air. Also when you do all the calcs, condition based MEV isn't much worse than MVHR. You need to factor in install cost, buying the hardware, running cost, filter cost etc. It only allows air exchange if it's needed based on humidity, not all the time. Plenty of nay sayers on here, but I did all the calcs for our house and it was pretty good, but our airtightness and building control, means we have to have a balanced ventilation system, so it had to be MVHR.

Both in a bedroom, no issues anywhere else, you just turn up the tv or radio as required.

We had a Flymo for about 6 years, first few years great, then the battery charger failed, replaced, then battery went and a few other niggles needed fixing, basically became uneconomical to fix. Went back to a normal mower after that.

Been there, then when it rained wished I hadn't, made a racket. Since then velux and roof lights in general have been of the agenda in bedrooms

That is a small area, if the concrete is on insulation, it should have a plastic sheet between the insulation and concrete. So would imagine a day's work to remove, another day to backfill. Builders job to rectify at his cost, he messed up. To correct or make a rubbish floor flat, is a self leveling screed, just build up low spots to match high spots.

Conversely my 192m2 floor only has about 600m. Build of ICF depends on system used. I did our walls in Durisol, 70m perimeter and up to 3.5m high, two of us neither done building work, took us 4 weeks doing 8 hour days x 5 days a week. That was completed the 4 weeks before Christmas.