UFH spacing on a 100/200mm slab

[Inchbyinch]

Hi All,

We are building a passive slab which ties into a warm retaining wall. The footing for the retaining wall is 200mm thick and takes up about 60m2 out of 140m2 and I'm wondering about the UFH spacing on a slab in this area. I'm thinking 200mm, the same as everywhere else. Will I just be heating up the slab? Also I'm looking to clip the UFH in under the rebar, has anyone ever done this before and any advice. 

If the zones are crossing two rooms can you run the UFH under a supporting wall?

Is there a way to calculate the heat output of an UFH circuit?

thanks again,

ed

[PeterW]

Ed - you can download a product called loopCAD free for 30 days which allows you to play with the layouts. 

 

When you provide the u values etc it can calculate heat loss and therefore heat load based upon the number of loops in a slab etc and the temperature of the water. I've done a couple where it suggests 150mm in some rooms and 200mm in others. 

As long as you use a sleeve you can go through walls however it's usually easier going through the doorway if possible

Couple of schools of thoughts on the rebar and cable tie solution as some have done it (Jeremy I think) and some have put a clip system in first and then put mesh over which lifts the mesh but protects the pipes.

 

 

[IanR]

For mine, which has been installed, but not commissioned (I'm just up to floor level), the calculated 6* layout was 300mm centres within a 100mm thick slab. I went with 200 centers for better cooling performance, if it is needed.

Thickness of slab at the footing shouldn't affect heat loss assuming EPS thickness is maintained, however the retaining wall may as it is extra connected area that is unheated. This will need to be taken into account for your heat loss calcs so may require closer pipe spacing in the floor to make allowance.

My pipe is clipped to the EPS, with mesh over, and I do have a pipe run running under a load bearing wall. For me I was told I only need sleaving if there's a joint in the slab, which I haven't got.

Here's my a link to a thread showing my floor:

 

[Jeremy Harris]

Our pipes are on 200mm centres, cable tied to the steel fabric in the slab.  Seems to be absolutely fine, as the water flow temperature is never very high and so the slab tends to be at an even temperature all over, with no cool or hot spots that we can notice.