mdproctor

To be fair the builders work so far has been top notch. I think the problem is that they refer to Florad, who they consider the universal truth on the matter. This caused the conflict with plumber pressure test (see other post) and the plumber. The parties agreed to disagree and the plumber can leave the system pressurised.

However during this process I learnt a hell a lot about UFH, materials, layouts, installations etc. And now a little konwledge has become a dangerous thing. As the Florad design differs from what I've read about best practice, where you try to get the most amount of hot water where the most heat loss happens. In my case that would clearly be the bi-folding doors, but their design doesn't do this.

I've emailed one design company, AstraCad, asking them what they think. My hope is they'll tell me I'm worrying about nothing and that it doesn't matter that much. Although I'm not sure they will advise a non-paying customer..... Not sure which other firms would be willing to advise someone who isn't their customer....

Mark

Hmm, polypipe is seriously tough pipe, often used for incoming mains water, the thick walled blue stuff right?

I cant imagine why it would need to be pressurised during screeding, you can drive over that stuff and it wont collapse...

Still, you loose nothing by keeping it pressurised, regardless of manufacturer..

The plumbers answer was that the pipe is cold and will expand when heat is put through it, but keeping it pressurised you ensure expansion room.

The builders use Florad and Florad advised them that this wasn't necessary. So a bit of a "****ing contest" happened between the two parties and the plumber walked off the job. I then did my own research and saw that many companies (polypipe, jg) do recommend to keep the system pressured through during, as the plumber said.

I've since persuaded the plumber to come back onsite, the compromise being the system remains pressurised as long as he feels fit. However Florad are still adamant he is wrong, and I personally would like to get to the truth in the matter.

builders are about to fit my UFH and have provided the layout found below from their designers. The floor area is about 36M2:

I added the external doors, and external walls text and lines myself - sorry for sketchyness.

I've done a fair bit of research on UFH and layouts and this one seems sub-optimal. It uses a single serpentine to cover the entire room.

My understanding is that the design should try to ensure the pipes run along external walls and windows. Essentially the hottest part of the pipes I beleive need to be by the bi-folding doors (u-value 1.6)

I would have expected double serpentines in the rop right and bottom right corners.

I rang the design company with my comment, their answer was "we've been doing this for 25 years and it'll give you an even temperature throughout". Which wasn't really the helpful technical response I was hoping for, as I was hoping they would give me a technical reason as to why I'm worried about nothing.

So my question is. Does the layout really matter that much? Is their's fine or is their's suboptimal? i'm really hoping i'm worrying about nothing.

Things have already been a little contentious with the builders with the UFH - who fell out with the plumber last week, who then refused the work, I had to beg him to come back onsite (see http://www.diynot.com/forums/viewtopic.php?t=266267&start=0&highlight=). So I'm trying to decide whether this is not worth fighting over and let them just get on with it, as the difference wouldn't be that noticable. Or do I need to push on this and find another designer as they are making a terrible mistake. I just don't know.

Mark

Polypipe, JG and others state you must keep the system pressurised throughout the screed drying period.

Others, such as Florad, state that pressure only needs to be maintained until the screed is laid, and that it does not need to be mainted for screed drying period (3 to 21 days, depending on the screed).

Who is right, and why?

Mark