JohnMo

Following a hurricane - one house left, the Durisol house being constructed. Doesn't rot Doesn't burn Doesn't seem to blow down (once concrete filled.

If you going that direction, you will need a vapour and airtight membrane inside. Then the wall airtight layer makes sense internally, not external. Then bond the ceiling/roof membrane to the block work inside.

The unit may have a cooling module. Which I assume is a small heat pump. You can adjust the set point at which this operates, factory set point is 23. But if altered from this say to 20, and the extract air is 21, then cooling mode will run continuously. Worth a look. hybrid_cooling_brochure_1_.pdf

Not saying don't go that route, just the amount of holes in the blocks, may make the process less cost effective and difficult. Seal the blocks first, then fill boots.

If you know the rules, do it correctly, or don't, up to you. You know the answer to your questions!

Looks pretty similar to Titon units, but they only have 4 potentiometers. Setback speed is just a calculation. So speed one (assume a setback speed) one pot for extract and one for supply fan. Then same for normal and boost. So just two fans and adjustable flow rates for each speed of the fans. I would leave these settings well alone. Look for a duct heater upstream or downstream of MVHR unit. Switch it off does it fix the issue?

I wouldn't go that route with Durisol without first sealing every block.

I come from an engineer background at one point in my career I was working to 0.0005" or 0.0127mm. Walls were done to less than millimetre where this was possible.

Just found the long external wall - about 15m long and 2.5m tall.

Photo for clarity on what an unfinished wall looks like. This internal but exterior the same

@lizzieuk1 I would do the maths on additional external insulation is it worth the expense and head ache? Moving from 0.14 to 0.12?

Sorry you are all over thinking this. Durisol blocks have a slight taper to allow them to be removed from moulds. But it is slight. The wall when complete will be vertical and straight. Apply flexible external tile adhesive and just apply slips. We did stone slips with zero issues direct to block. By the time you have completed it the wall will be mostly airtight. The issue is the DPC area, but this acts as a drain should any moisture het behind the slips. Forgot to mention the securing tabs on the slips, I use copper nail but can also be screwed directly to blocks

Think you may be confusing them, they input to a strategy, they ultimately take responsibility for a design they don't understand. Basics of heat pump install and UVC is simple especially if connected to UFH. You maybe simpler, to draw up design pipe sizes from A to B etc, and say you want a plumber to implement. Buy all the odd stuff like manifolds your self. I would start a new thread or two, one for your plumbing design (cold and hot water) another for heat pump. Draw up your base plan for each and get it reviewed and commented on.

Just zero point running 22mm cold to each room. Do it 15mm, it is more an adequate. Why would you need 22mm hot anywhere? As the crow flies our ensuite is 15m from the UVC. If I switch the shower on (with hot water circulation off) by the time I am undressed the shower water is coming out warm, another 10 secs it hot. All 15mm plastic pipe. 15mm hot or cold to high flow shower or bath is fine. 10mm to sink if you want to run additional pipe to bathroom. That is a bonkers flow rate, why would you even need half that?

200mm PIR is nearly equal to 300mm EPS. For the same internal space both options are similar.

U value calc will be pretty much the same as a floor. No. Concrete isn't an insulation it a good conductor of heat, add another 100mm of PIR, would bring your U value closer to 0.1. The ground is always around 6 to 8 degs. So heat loss will be constant all year around. You don't get the extreme cold of air temp but you don't get the warmer temps either.

I am reading the secondary flow is higher than the primary and that is the reason for the LLH. If that isn't the case why install the LLH? If secondary flow is higher than primary then the distortion illustrated will be there. If it's the other way about primary flow is higher than secondary you get similar distortion, but with return temp to boiler higher than coming back from the secondary side. Add zones on the secondary side you have one system that cannot do what you want or expect. Flow temp or return temp will always be compromised for the boiler side.

So you have two very different flow situations on primary and secondary sides of the system. This is cause huge flow temperature distortion. Basically you will have return from secondary side going back to the satisfy the flow to secondary side.

What I find amazing is Heat pump installs now avoid a LLH or buffer like the plague, because they rob efficiency, cause distortion in flow temperature/return temperature. Generally a waste of money at time of purchase, and then rob efficiency for ever more. Distortion and driving additional pumps. Now they are being installed on boilers - why? They bring nothing to party (that is good), as the whole of this thread seems to show.

Caberboard is water proof with a coating, I would be worried about the adhesive just lifting after a short while. So you may have to do something to act as medium to allow a sound connection. Maybe an overlay of ply or something similar? What do the caberboard instructions or website say on the subject?

OSB foam glued to parge coat.used to attach pipes and the top channel for all wiring. 50mm battens used on walls and ceiling.

If you include an unvented service cavity it come in at 0.14. Work out where you need the airtight layer so it concedes with the ceiling, roof etc. then go from there. But inside is best as above. But your call. Airtight can be parge or membrane, battens can be packed out if needed to get straight vertical walls. Advantage for doing all this internal, it's not weather dependent.

If you are concerned about water etc, wasn't block and beam the design solution made for you? Not a fan of block and beam, but it moves all insulation away from possible water and may be the correct solution here.

Or even the MVHR sub forum?

You can use the floor as a storage heater. So a simple thermostat is used to start heat pump during cheap rate electric period, the heat pump just adds heat energy into the floor. Once you get a low energy system the floor becomes quite self regulated. Heat out from the floor is a product of area and delta temperature between it and the room. The closer the dT the lower the output. Summer cooling is similar to heating but it's sucking room heat in from the room. You keep away from condensation issues by flowing relatively high temperature for cooling, my flows vary between 18 and 14ish. This is the side pipe temperature, floor surface temp is a couple of degrees lower than room temperature. Not sure passivhaus ever say you do not need heating, they say you don't need conventional heating systems. People think that means no heating, which isn't correct. The fact that passivhaus state a max heat demand of 10W/m² is purely to allow air heating via MVHR. So our house at around 200m², if Passivhaus certified would need 2kW of heat on the cold design day. Or 48kWh.