Calculating number of clip rails for UFH

[Conor]

I need to order clip rails this morning. Don't have time to go though all the drawings and figure out how many I need.

 

We have 180m2 in total of UFH being laid with 900m of pipe at 150-200mm spacing. From what I've read the clip rails should be spaced every 1m? So in my brain that's 180m of clip rail unless I'm being thick?

[Nickfromwales]

Are you laying serpentine or inverted ?

I just laid 1.3km of pipe at 100mm c’s reverse / inverted ( snail ) and went through 250 m’s. It’s area rather than volume with you, but you’ll still do the 180 in or thereabouts. Boxes are available at x100 per box, so just get 2 boxes if I were you. They’re around a buck fifty a strip, so chicken feed, and recommend putting them at 800mm centres. Last thing you want is anything lifting ( floating ) during the pour. 
What are you fixing them down onto? 

[Conor]

Cheers @Nickfromwales It's mostly counterflow spiral (in loopcad speak) and standard serpentine for some smaller rooms. About 80/20.

 

I'll order an extra box - just wanted a sense check in case I was off by an order of magnitude or something!!! 

 

I'm using PERT EVOH barrier pipe - I've heard that I'll also need to staple the bends down as well?

 

We're going to on top of thermal lightweight aggregate (TLA) and polythene sheet.

[Nickfromwales]

 

@Conor

That’s how I laid on my current full project. Hope that helps. ?

[Nickfromwales]

I bought a Spit Pulsa 40e gas nailer ( concrete and steel fixings ) for £499 and it paid for itself with this one job. All those rails and metal P clips for here and there fixed down with 25mm concrete nails. 

[Conor]

Work of art.

[Nickfromwales]

6 hours ago, Conor said:

Work of art.

2 days with marker pens, then line marker paint, and more head-scratching than the pics show. That one was "measure 6 times, cut once" and I still had to 'improvise' with a few of the tricky areas.

So you know, I literally painted a 100x100mm grid onto the floor in each room, in yellow paint, and then painted the actual pipe runs on with red / white / blue as the lines to follow when affixing the clip rails and laying. Anything less would have resulted in "work of art" being "looks like shart"  A lot of hard work, head work, and time to get that down I assure you.  

[Mr Punter]

It may be useful if you could get a cheap (self adhesive?) 100mm grid layout mat.  Maybe 1m wide rolls.

[Mr Punter]

I don't like the way you end up with loads of pipes close together on the home run in ufh layouts.

[Nickfromwales]

9 minutes ago, Mr Punter said:

I don't like the way you end up with loads of pipes close together on the home run in ufh layouts.

With PH it’s very much academic to look at ‘hot-spots’ as the flow temps and room temps delta are ridiculously close together, but even with my current job which will smash PH I still had to follow my heart and isolate the longest runs ( with Insulaton ) to preserve the temps at point of origin to the rooms / zones that it was to service. 
 

 

For clarity, Flow pipes only were insulated.

Edited November 12, 2021 by Nickfromwales

[Conor]

Not nearly as neat as @Nickfromwales work but we're getting there. Plumber has already told me off for not going close enough to the bi-folds ?‍♂️

 

 

 

How important is it to insulate the flow pipes out of the manifold? And for how long? I've 4 flow and 4 return going through the one doorway and narrow route through the kitchen. We've only 40/50mm of liquid screed so I'm not sure we've the depth for insualtion. Flexible conduit?

Edited November 22, 2021 by Conor

[Nickfromwales]

4 minutes ago, Conor said:

Plumber has already told me off for not going close enough to the bi-folds

Actually you are spot on to leave a perimeter there, and I don't run into the openings either as that's the 'coldest' part of the floor in terms of difference in the cold from the sliders and junction with the outside walls vs the heated slab / screed. The amount of time you'll be stood barefoot on the "cold" 100mm of floor you've not piped = never. That one can go into the 'chill out' folder  

Makes it a lot easier to lay out with a few markings on the floor for ongoing sanity!! Top job  

With 40-50mm of screed, you wont be insulating any of it. I mostly do that where we are employing slab cooling for a client, vs no 'real-world' need when heating only, so don'y beat yourself up over that.

Just be sure, very sure, that your pipework cannot lift ( float ) upwards when the pour goes ahead. With 40mm as the least amount you'll want zero movement from the pipe. Looks like you've got that covered TBH as you've gone on about the same gaps as I do, eg belt n braces.

Tres bien, Rodney.

[Nickfromwales]

On 12/11/2021 at 21:44, Mr Punter said:

It may be useful if you could get a cheap (self adhesive?) 100mm grid layout mat.  Maybe 1m wide rolls.

Just saw this. Yes, it would be good if maybe the slip membrane was supplied pre-marked. Sadly I wanted the screed in full contact with the subfloor for the two to act as one, ( for higher "thermal mass" lol  ), as the above is a >PH project so had an extra bit of 'attention' with most detailing.

An 8x4 of 6mm plywoord drilled at 100mm c's would have been the kiddy me thinks, so I could use marker paint to quickly dot a grid down. 20/20 hindsight eh ?!  Thankfully I do these over-slab installs once in a blue moon, with all others going into an insulated raft with pipes affixed to the reinforcing mesh. Saves so much extra work!! 

 

[dpmiller]

@Conor, you still need more rail?

[Conor]

Yes. Tho I think we've enough for the current floors, but will need your box for the basement.