Wrt43

Thanks Nick for your help. I’m going to reinforce the limecrete floor as you say. I was just thinking about the layout of the pipes today - can’t work out which way to go. Is there a standard method of arranging the pipes? My alternatives below.

Thank you. 75mm gives me the space for 150mm of PIR. I really wish I knew about EPS before I started. So much cheaper! Just have to use it on the next house!!

Thanks both for replies. Yes, the 75m2 is split evenly between two floors. Nick, I wish I could change the oversight! Blame myself really because I didn’t put enough effort into finding resources like this forum before I started. I think I put 125mm of concrete down which whilst very useful to build off I can see is undermining the performance in the heating. Is there anything you would suggest to improve the performance of the floor - short of taking up the oversight, please don’t say that! So to clarify all I have to do if I keep my manifold where I originally planned is to estimate the length of each run, if I’m over 100m I need to go off another port and do the remaining area with a separate loop. Do the pipes which are going some distance before they reach the desired location for heat need any additional insulation around them? Or is standard pipe work sufficient The other query is centres - friend of mine who has a similar set up,125mm PIR on oversight, did his at 250mm, though I’ve read 200 is the standard? I feel like there must be calculations I should be doing but don’t know where to look! If there are formulas for this stuff please point me in their direction! Solar will be PV. Thank you for tip re measuring mains pressure.

First time self build for me, wish I had found this site sooner! I apologise if any of this has been answered already in depth, I’ve had a read about but still a few questions remain. I have read the posts on UFH here and just wanted to clarify what I’m doing sounds sensible. And looking ahead for the next 2 months I need to finalise the heating system design with the plumber. House is part old, solid walls, single glazed sash windows, this totals circa 75 m2 split evenly between GF and FF. the extension is a further 65 m2, this is cavity walled with 75mm PIR insulation. The extension is all single storey. Floor or is the old house is 1. breathable membrane 2. 150mm geocell glass aggregate 3. 100mm limecrete screed with UFH pipes in screed attached to plastic mesh. Floor of new is 1. Compacted stone 2. Concrete oversight 3. DPM 4. 125mm PIR 5.. 100mm screed concrete with pipes in screed What I am unsure about is manifold position. I understand a central manifold is desirable but I’m really going to struggle to find a place to put it. I had planned for the manifold to be in the laundry, along with the TS, being fed from an outside boiler. However this is definitely off centre. I have attached a quick sketch of the place - distance from laundry to edge of zone 3 is 9m, going along the outside walls. I am concerned have a return from this will lead to a cold spot in the floor, and am unsure whether this is too longer run from the manifold. Zone 1 is old house, sitting room, zone 2 is kitchen / diner, zone 3 downstairs loo and bedroom/ensuite bathroom. Secondly, the design of the heating system itself. DHW requirements will be 2 showers back to back in morning, then a bath / shower sometimes at the same time sometimes staggered in the evening. Then what I presume is typical usage for washing up etc. What I’m unsure about from reading the posts here is 1. How does one judge whether an accumulator is necessary? Mains feed is fairly feeble but I haven’t measured it - is there a threshold requirement? 2. I was planning an external [ oil ] boiler, family always had Grants so would look for the same, thermal store to feed Rads on upstairs of old house, UFH through out ground of old and new, and then DHW. How does one spec a thermal store? By this I mean size, size of coil, immersion heater requirements? 3. I plan to install solar next year on the outbuildings, 10kw, and would like some guidance if possible on how to future proof the system to take advantage of this. Thanks all Bill