Barnboy

Does wind chill not affect the performance ? If an ashp was facing south in a sheltered location on a sunny winters day with a chilly easterly wind would it not perform better than if it was in a shaded spot with the wind blowing straight at it ?

I got the weather data from the local met office when I had to get the u-value calculations done for my bco. I'm in sunny Jersey ☀️ although the ashp would face east with nothing between it and a good easterly blowing in from France. I'll ready through those papers later when I can see them on a bigger screen. Thank you.

So I'd be looking at needing a 4kw, or the nearest above that ashp if my calls attached are correct?

I'm still to get an air test, not cheap and I'm not air tight yet. I've filled in Jeremy's heat loss calculator, to try and get an idea of ashp and ufh sizing. Firstly I'm not 100 % sure which figures I should be using fromt eh calculator to work these things out as there's Total heat loss, Inside vs outside heat loss, Total daily min and average, I had someone round to look at giving me a price for them to supply and fit, and also which would be the best position for a unit and route for pipework into the house. The guy did a rough calc on his phone of 40w/m² for ufh multiplied by 90 for the m² footprint of the building, saying I then needed 3.6kw ashp capacity, He then said as I have no heating on the 1st floor, only power points if I did want to put panel heaters in the future, I'd need to double the capacity of the heat pump. Is his theory correct that I'd need to double up having no upstairs heating, and which figure on the calc do I use ? Thanks

Thanks, I'll try and get some to try.

It's timber sill boards on to marine ply, I've got some low foam adhesive left from other tasks but don't mind using a adhesive of that would work better. The timber boards have a slight cup in them so will need a little weight until whatever I use grips them. Do you have a recommendation for an adhesive ? , no more nails, pink grip ,sikaflex ?? Thanks

@Russell griffiths Thank you, i seem to over think everything and you've just given me the simplist most obvious answer that I never thought of. The window boards / internal sill boards are to be fixed down to some solidly fixed marine ply, the underside will hopefully never be seen again so as you've suggested, I'll give them a coat of paint on the underside which the adhesive will stick to nicely. Thank you.

I've got to fit some timber window boards that I've made, the plasterer wants them fully sealed and in before he skims. I've read on here about gluing them down instead of screwing but can't find the thread now. My question is.. is glueing a good method ? I was thinking something like sikaflex or no more nails with a couple of weights on them for a few days. Also if they're oiled both sides to seal them from the moisture when skimming, will sikaflex, or any other glue adhere to the oiled surface at all?

I had a look at the ones you recommended and searched for others too. The ones that I linked to, that are already fitted to my windows are recessed into the frame so I need to find something either the same dimension, or something very similar to cover the recess but also fit int the recess of the head of my window box.

What do people get charged on average for an air test ? I've just been quoted £450 without a certificate ? Also I've got these https://www.ironmongerydirect.co.uk/product/trimvent-xs16-upvctimber-window-vent-surface-312-x-16mm-white-931161 Trickle vents, I've been searching about and can't find a humidity version that would be a direct replacement, does anyone else know of any hidden somewhere please ? Thanks

Changing the AC/H to 0.2 now gives me a total heat loss of 2536 .

Yes, we thought the architect was good, we'd been given good reviews of him and he was high up in the architects association. His price was simple to understand, as opposed to the other architects who's prices needed a lawyer to understand. He didn't like it when I said that I would be doing as much as I can as that was the only way we could afford to do the build, he told me that I could probably do the plasterboarding ! He even wanted to leave the original 1st floor joists that were rotting in the walls. I will look I to MVHR but we're working on a earn it to pay for it basis at the moment, Covid price increases have wiped us out. I've just had the 1st floor plastered so whether it's even possible to fit now, I don't know.

I haven't been given any target to hit for airtightness, the architects details just state "Thermal bridging and air leakage Building fabric to be constructed using accredited construction details for limiting thermal bridging and air leakage" I didn't know ow anything about airtightness until I'd started. I've fitted Tyvek Airguard Smart from top to bottom and all around, it's taped to all the windows, any penetrations are taped with their flexi bitumen tape and any corners also have a good dollop of sealer to do the best I can. The only area that hasn't got membrane is on the top of the 1st floor heads of the studwork as that was already up when I discovered I needed to fit a membrane. Here I have the membrane taped up to each side of the heads so any air can only pass through the actual timber if that's possible. I've not got MVHR, I never knew about this back then either. We visited the Self build and renovation centre but there were no exhibitors there, only stands to read which I couldn't absorb, that's like reading a book to me, by the time I get to the bottom of the page I've forgotten what was at the top. Ventilation is from trickle vents on the windows and shuttered extractor fans in the bathrooms and kitchen.

These are my inputs, I need to measure the walls and windows etc accurately and just went from memory last night, but I don't think that I'm far out with those. I can't find anything relating to air changes in any of the architects paperwork ( He pretty much abandoned me when I said I was going to self build) everything is taped and sealed as best as I can do it so I'm pretty sure it's well done, a sparky mate who's on sites everyday keeps telling me that I've gone ott with my membranes and taping.

I still haven't managed to get to the stage of ordering anything UFH wise yet but have been going over and over this in my head. I've got 140mm of Insulation below my already laid 65mm screed, this gives me a u value of 0.18W/m²k. Using Jeremy's heat loss calculator and some off the top of my head figures I get a total heat loss of 3268W with a floor area of 90m². If I understand this correctly and have filled everything in correctly I work it to equate to about 36w/m² of ufh being required??? If I was to opt for the Variotherm gypsum panel, this in my thoughts would basically act as part of the screed but with the pipes 65mm upwards of the insulation and about 45/63mm below my ffl. Would the insulation u value and depth compared to the pipework allow this system to work to a decent standard or would there (A) not be enough insulation (B) the height of the pipes in the build up not allow the slab to work as a thermal mass well enough ? I've read on here of people having their pipework midway up there slab and also having 100 -120mm of slab with ufh. Any inputs to help my understanding before I loose anymore sleep and hair over this. Thanks