JohnMo

Our gas pipe runs through insulated Posi rafters and is run in Copper (22mm). New gas boiler circa £500 to £1k, make the heating system low temperature, to future proof. You may need a buffer tank. Combi or system boiler up to you. If you do use a combi, get one that take preheated water such as an Atag, then you can have a cylinder upstream of the DHW that allows to use to solar preheated water later if required.

And piping from water main to house is usually plastic and the water main is either plastic or lined in plastic - plastic everywhere

The 3 column one is 2853 BTU. https://www.homesupply.co.uk/Eastbrook-Rivassa-600-x-608-Gloss-White-3-Column-Horizontal-Radiator?gclid=Cj0KCQiAip-PBhDVARIsAPP2xc182-ebOJ-_LCV6gYPnx90wMzdnD3iF7siji72roHjODDIc6FgneJ8aAjcBEALw_wcB That would be better suited. If you are going ASHP, the bigger the better really, even go the next size up if you have room

I used GRC Aquatech in Aberdeenshire

Used PERT-AL-PERT pipe which can be used for the UFH, general plumbing throughout the house including supply water to drinking taps.

Did a simple Google search for the number of columns and overall size found this, different colour, but same size and number columns, which gives a T50 rating. Will be pretty similar if not the same rating https://www.homesupply.co.uk/Eastbrook-Rivassa-600-x-608-Matt-Anthracite-2-Column-Horizontal-Radiator

Where are you in the country?

We mounted the boiler on a large piece of 18mm ply, on an external insulated wall. Plumbed in plastic. Except close to boiler. Floor in Caberdeck chipboard 22mm thick, glued with D4 expanding wood glue used at all joists and all joints. Expansion gap at perimeter.

Daft question, why do your heat loss calcs have zero for all ventilation losses. The MVHR is not 100% efficient, so there will be some losses, which will add to the heating kW required? Our ventilation looks to add 11% to the heating loads at 0.5 ACH.

Not sure of you ground floor make up. But could you bury these pipes in your floor insulation, use that as your insulation, put them in flex conduit so they are replacable to comply with building regs.

Hence put it on thin to fill gaps and pin holes only. Broom in photo is the size I used for applying hithe parge coat. Mine is on Durisol blocks and you can see the blocks clearly.

I mixed mine to a double cream thickness, then got a few cheap natural bristle brooms, rubbed it well into surface, so it had no pin holes. Once dried, had a look over and where pin holes had occurred during drying gave a second coat. When attaching battons I used a hybrid seal in the holes for the batten screws. We used tapered edge plasterboard and taped the joints. (Dry lined).

Overall seems a complicated roof to build. Why not. Metal roof. Suitable membrane Ply Rafter Under draw with counter battens to suitable thickness Spray foam to circa 350mm Airtightness vapour control layer Comments on your build up As said above. I used Passive House Systems, reflective air tight vapour barrier. Their primer on the parge coat, then the airtight adhesive. All joints and staples taped. Photo of roof and wall prior to battens. I don't believe the open cell foam is that airtight, as I missed some taping on the ceiling and had an air leak at that location. (air test prior to plasterboard). To If you are doing a parge coat add some lime to the mix, give a better mix for brushing on and stays more flexible after drying.

Have a look on the manufacturer website, they now list various delta T, if not give them a call or the UK agent.

This kit is a 4.5m pole. https://www.ungerglobal.com/uk/products/stingray-indoor-cleaning-kit-450-os Not cheap, but in theory would give a 6.5m + reach., So give s tick in the box for internal Window cleaning. External can be by ladder or wet pole as above suggestions

You could use a pipe stat, close to the pump. Set at say 45 degrees and wire the pump live through the normally closed connects. If the flow temp goes above where it is likely to cause an issue the pump gets switched off.

We did parge, but at the DPC we did a coat of airtight paint, as the diagnostic air test showed a leak there.

I would just bite the bullet and use a single Sumamp. Anything else is just p***ing about if you are going ASHP, with your space constraints. The other is install cylinder in loft space, if you have one. Or stay with gas. And wait for high temperature heat pumps to come available.

No dry lined and taped - that's the Scottish way.

You can use Aerogel, which give bout 20% improved performance over PIR for the same thickness, for 3x the cost. Or get some thin PIR and foam into place

If you have a smart phone, download CDM regulations App and there is a H&S form to fill in. Takes 20mins. You are then the Principal contractor.

Depends where you are in the country, in NE Scotland you can't easily get plasterers. So a parge coat makes sene. For a parge coat, I mixed 1 cement, 3 sand and about 1/5 lime, mix to a double cream thickness. Get a few natural bristle brooms and apply with them. Rub into surface so all pin holes are filled. Plan on a couple of days for two people, depending on house size. When attaching battens I used hybrid sealant in the holes.

You don't notice them after a week in the house and it's all furnished, too much other stuff for your eyes to see. Spend thousands, if you need to, but I went with Aico and didn't.

You just don't notice them after a week in the house

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