westcoast

Really interesting, thanks for that info, I need to accurately get a figure for my heating load. Will work on this over the week. For my 'good' Air-Tightness I am going to spend as much as budget allows, which means: - Intello membrane internally, bonded to scratch coat on walls - careful taping to window reveals, doors etc - Correct cable entry grommets used when membrane needs to be pierced - Chasings and below screed wall to be coated with sprayable liquid sealant Unfortunately the stove is an aesthetic decision and is 'non-negotiable', it is of decent quality though with triple insulated flue.

You are right, sorry, I was assuming Kooltherm was just standard PIR insulation, I had looked at Kingspan a while back before we compromised and decided it would be our only option... The question is, how can I calculate the heat release time for different thicknesses of screed? .

No chance to move floors: windows and doors are in. Large sliding patio door would catch on floor if raised. it was 150mm EPS originally planned, will check with our engineer, but 150eps and 100 pir roughly equivalent, no? Not spoken to BER assessor yet, but it could be a good time to get in touch!!

Thanks for the detailed reply, I was getting a bit worried about 100mm being enough insulation (we had originally left 150mm but had to make compromises..) The online Kingspan calculator works out at 0.14 with 100mm insulation: https://www.uvalue-calculator.co.uk/calculator/floors/ground floor/solid concrete - insulation below screed/0.5/100/ I could possibly go to 110mm insulation (achieving 0.13) if using a 55mm liquid screed - I suppose this would only create a 13 ton storage heater! But there is an obvious trade-off here with: more thermal mass and slower release vs. less heat loss overall Thanks this is great and puts it in perspective.. I think I saw a spreadsheet on here somewhere to calculate ones heating load/requirements, I should really find that and try to make a more precise estimate. . The good thing for us is we have a small stove for heat NOW! ... but I take your point, its a careful balancing act, your demand cannot exceed the cost threshold making all the effort redundant. Having to use the Willis heaters throughout the day would be a fool's errand. That was brave move indeed, but I understand what its like to spend a lot of money on insulation. I want to gauge the performance of our house over a year or so before adding anything too fancy - hopefully the Willis heaters will be sufficient anyway. I suppose my main concern now is Screed thickness vs extra floor insulation, will a thinner screed make the Willis idea useless as the heat will escape shortly after off-peak hours.. ? Cheers

Thanks for reply.. thats good advice re ufh pipes.. already 50% into build though so it will have to be PIR at this stage..

very interesting, thanks for this, is that Irish code or UK I guess they are pretty similar anyway. Sounds like PIR is probably a safe bet

Thanks for your replies Peter, we will have MVHR and the house is well insulated + lots of thermal mass (block-on-flat construction with 200ewi) didnt see the need for every room to be heated, also in my experience living in a house with UFH, it was never used in bedrooms and very rarely in living room.. Just been reading up on some of your knowledgeable posts about Willis heaters, one thing comes to mind: Most people seem to use Willis heaters to heat whole slab with E7, which would slow release throughout the day.. but we have insulation on slab and a 70mm screed. I wonder if the floor would still be warm in the morning? and would escaping heat just be trapped in our wall thermal mass anyway? btw our 70mm screed only gives us space for 100mm insulation below, will have to use high performance, maybe PIR? thanks again!

Thanks a lot for reply. So rising main directly into Sunamp is sufficient? ..but without power showers I'm guessing I would need to increase pressure after heating?

Hi all, I am currently in the middle of a new build (roof is now on). I need to start making decisions on heating/plumbing and I wanted to get some advice before proceeding. My idea is to use off-peak power supplemented with a solar array to run 2x Sunamps for DHW and UFH. The house will have a wood-burning stove, so although I will install UHF plumbing during construction, I might not utilize unless we feel we need it. quick info: - 2 bedroom Bungalow 120m2, well insulated (200mm EWI), triple-glazed, good air-tightness. - I plan to use Sunamp UniQ9 HW+iPV for DHW and another for UHF (UHF will be in two bathrooms and kitchen approx 40m2) - 2.3kw solar array (flat roof mounted) - wood burning stove 5-8kw Some questions I have so far: For DHW, am I right in thinking I need a unvented pressurised system for this set-up... as a pump is needed to draw water through the Sunamp? Is there any need for an expensive solar PV diverter? Surely I can just have a switch with a timer for sunrise/sunset after the inverter? Thanks everyone!! --

Hi there, currently in process of new build: 2 bedroom bungalow with EWI Looking for advice for designing a dual Sunamp setup for DHW and UFH. Planning to run these with off-peak power and 2.3kw solar array Cheers