yoclick

Thanks, but does splitting the 28mm to 2x 22mm create an issue? Per heatgeeks guidance, permitted load is spread evenly it seems it could be fine but not understanding the hesitation from the forum? I'd rather that then drill the steels especially since it would mean deeper notches on floor joists either side (most likely outside of regs compliance) as you won't be allowed to drill above central line.

Hi all, Any thoughts before I proceed? Thanks

Thanks all. Some additional information so you can have some comfort I havent plucked figures out of thin air: 1) House is 130sqm, 1950 but renovated so using 60w/sqm (higher end of heat geeks cheat sheet) gives circ 8kw. 2) Extension will be ab additional 160sqm at 40w/sqm (again, higher end) gives 6.5kw. 3) Total is 14.5kw rounded to 15kw. Again I recognise I've added a rounding buffer to already other buffers. 4) 28mm pipe using heat geek cheat sheet is slightly worse than dt7 at 15kw. Not ideal but with the buffers above I reckon it will be around or better than dt7 in reality. 5) Obviously 22mm is therefore not sufficient but as stated in my OP, my plan is to T the 28mm after the water cylinder. 6) Water cylinder and ASHP will be within 4m of eachother, with the pump 1m within the external wall. So key for me in my understanding of point 5 as I'm doing some 22mm piping now and want to ensure I'm going to cause a problem later on. Thanks!

Just over doubling the size of the original house

Hello all, Firstly nice to join the forum. Im doing a fair bit of renovation now in prep for a rear double story extension I'd like to do in a year or 2. I would like to install an ASHP eventually after extending so just want to future proof myself now while I have the chance. I estimate the house need is 8kw currently and c. 15kw post extension. Im looking to install 28mm pipe from boiler to hot water cylinder, and then 28mm from there to centre of house, then teeing to 2x 22mm feeding each side of the existing house and then 15mm at rads. All in copper. The reason for not running 28mm all the way is a steel RSJ getting in the way. When the extension is done, I fully suspect BC will request it to be a seperate zone. I was planning to run 28mm from water cylinder teeing to 22mm for upstairs and 22mm downstairs. Any thoughts, concerns or advice?