MikeSharp01

Anyway the click you need to watch out for is the one following the visit from the people in white coats that tells you that you are now incarcerated in a safe, secure and probably padded room of your own next to Jack Nicholson.

Are you sure it wasn't LSD (or some modern equivalent)?

I guess this delay is systemic in that it would be the same wherever it was placed provided the distance to the pipe was the same although the wall will have some effect - perhaps it insulates the slab at that point slowing the response time. It is essentially, in effect, the lag of the whole slab. Is it near a return run / an outward run or at the midway point in the run of pipe as I guess this must have an effect in the ramp up / down phases but probably drops out during the steady state phase once the steady state is reached. One thing is clear and that is that your experience tells us that using the slab temperature as a proxy for the room temperature is in effective because of the lag.

Yep. Applied engineering in my case. Ours is 150mm thick so much more of a sink below if we had the pipes just 30mm down - so counter factually you might think it better to have them even higher to speed up the response. Have you take an thermal image of the surface when it is running does it show the pipe runs clearly?

Thinking again - the two layer concept has other possibilities. In those areas where Solar heating occurs the pipes might be better at the top of the slab, where they could react more quickly to the heating and in those areas where it does not occur they could be down in the slab so as to bury the warmth from the solar heated areas into the depths of the slab. We have to accept, it is what it is, that a concrete slab is not a perfect conductor so the radiation pattern is everything. More thinking required....

Interesting, I will take a look and build a thermal model of this to see what might be optimal. We have three levels in the slab, the base and then two layers of mesh, at which the pipes could be pinned and I felt the bottom was the best but it may be that there is an optimal level. As a starting point I found THIS document which sort of shows my initial thinking for the model but as you move the pipes up in the screed the thermal dynamic changes and modifies a lot of features EG response times of the slab to both heating from the pipes but also the dynamic ability of the pipes to transfer solar heating. When operating in cooling mode things may change again and it may be that the best solution, largely impractical for cost reasons, would be to have two layers of pipes which could provide more optimal matching for the conditions met in the annual heating / cooling cycles.

The slab is heavily insulated below the UFH, to which it will be pinned, and so I guess getting it lower down helps make the slab more controllable in terms of heat flow - upwards and outwards so hotspots round the pipes are eliminated when heating and when cooling, which ours will be, we take heat out from the bottom of the slab. There may also, depending on the engineering of the slab, be a structural issue requiring it to be at a given height such as on or close to the neutral axis - not an issue for us.

We are on 48 hrs notice for a visit from our private BCO who is also doing the structural warrenty work. We have only had the excavation visit so far but the pipework fall / air test coming up. I did plan that for past Monday on the previous Thursday based on a just in time basis but we broke the dumper truck and so had to postpone. Learned my lesson there - Get the job finished then call the BCO and get on with other work.

Very good point, The pipes actually go around the trap itself but I agree it needs to be kept well away from the trap or well insulated.

Sad though I am to say it perhaps your best option is to publish via Amazon. They take a cut but you have some control the market is vast.

I am just laying out our UFH, on the drawings, ready to put them into the slab and I am trying to work out where they cannot go. I appreciate that services coming up through the slab must be avoided but my worry was what fixings might need to go more than 100mm, our slab is 150mm thick with the 16mm UFH at the bottom, into the slab and therefore must be avoided. I was making a list: 1. Fixings for the sole plate (outer walls). 2. Fixings for sole plate of internal stud partitions. 3. Fixings for the internal steel columns. 4. Fixings for the toilet pans if I cannot sort wall hung (or some later occupier might want to fit floor standing). 5. Fixings for the base of the stairs. 6. Fixings for the kitchen island unit. 7. ??? 8. ??? .... Other questions which feel like I know the answers as to where the pipes must go, under the downstairs wet room shower tray former and into the downstairs WC.

FOI, as @Ferdinand says, direct to the planners - otherwise you could be in for a very long haul.

So what does that mean for the seals around my joints - I thought the water test was used only if air test failed. I just re read PART H and the test has to be carried out after it is covered up so how does the BCO check the fall - I cannot imagine they want to make two trips? Mike

But that was then - now we have political science - which must be far lower than stamp collecting.

I didn't think you could have molecules of oxygen only atoms. A molecule being a collection of atoms which must by definition be bigger than any single atom but I guess it might depend on the number of shells so a pair of tightly bound low electron count atoms as a molecule might be smaller than a ganging atom with a high shell / electron count.

I have Sthil system and the chain saw is very useful on the end of the 3m extension pole. The hedge Trimmer is great and the Strimmer works better than my Riobi.

Yes I can for each of the two runs. I guess I will be able to see the leak. I have done 2 joints in straight pipe they are stable and fine so now it's the clever bits at the ends. One of which is one of those universal bends with two sliding collars. I have done the nuts up but I am never sure of them.

Floplast for the fittings and Marley for the pipe although some of the pipe is not branded. Came from drainage direct I think. Anyway have checked the test gear and no leaks so now I am going to test each joint and find the offending one. Although the sun is out now so getting it stable will be interesting.

Good point I will check that but did you mean 5PSI as this is more than my manometer can handle I think max I can do is +/- 30mb about 0.9PSI I think.

I gave just spent an hour or so playing with our underground pipe runs to see how well they are sealed. They are all still exposed so I can remedy things and it's overcast here so I should have stable temperatures. I am struggling to get a air pressure test to pass well, the pressure drops down to almost the lower limit on the 15 minute window and it can only be the joint seals. I used the flopast lube on every join and checked for scratches on the pipe. There must be a way to get a good seal on these things or are they designed to only just pass the air pressure test? Any thought anyone.

Yes so I have bases both sides so can be Kentish man and man of Kent although I was born West of Rainham mark, in Surrey. (For those not familier with these terms see HERE.)

And some might say that life at the bath manufacturers would have been extinct as long as the dinosaurs by the time it first sees any water, but I, as your Kentish compadre, could not possibly comment.

I think you can get much bigger than 90mm I have a 105mm skulling about somewhere.

Makes Perfect sense now you describe it. At 100mm I was using about 200m per zone (3 zones) at 200mm I am using 300m for the whole 105m2 so cheaper as well.

Anybody got any ideas on the spacing between UFH pipes. Our slab is 150mm thick and I was going 300mm grid but I notice that 200mm is more usual in 16mm pipe? Also I see that for an ASHP driven system a 100mm spacing is recommended!