CH pipework through floor insulation

[Daniel123]

As a part of my renovation project, I will replace/relocate some radiators and put plastic pipes (current pipework is kinky 8mm copper microbore). While things are relatively easy with upstairs, I am not sure how to approach downstairs. On top of the solid floor, I will have 25mm Celotex insulation under 8mm laminate (see figures below). My plan is to leave a gap between the wall and Celotex and put the CH pipes there, getting rid of ugly pipework dropping from the ceiling. My questions are:

1. 10mm or 15mm pipes? 10 would be easier to handle but I am afraid that the runs will be too long (about 5-6m from the main CH pipes to radiator). I am leaning towards 15mm; downstairs radiators need to work well.

2. How to clip the pipes under the laminate? Is there any standard solution that would fit into the 25mm space between concrete and laminate?

3. Most difficult, how can I connect radiators? I can see three options:

a) Ideally, I would like to have copper pipe between TRV and floor, and then under the laminate an elbow to connect to the horizontal plastic pipe. The main issue here is that, apparently, Speedfit elbows are far too bulky for the 25mm space under the laminate.

b) Fit the radiator high enough to allow for the bend of the pipe, like in the figure below:

c) Use a short elbow (like Towelrads 15-15mm Pushfit Chrome Elbow) and then run plastic pipe below/behind the radiator like in the figure below. Only one of the feed/return pipes will be hidden this way though.

I understand that some of these problems could be solved by soldering copper but I have neither the tools nor skills.

Any comments will be appreciated!

 

[Geronimoe]

Have you looked at using compression elbows with steel inserts.
Less bulkier than speedfit and personally i believe safer joint.

 

[Daniel123]

Thank you Geronimoe, compression elbow could be the solution to question 3! Just found an elbow that is, according to specification, only 30mm in length. If this is correct, it will be hidden entirely by the collar.

 

[endecotp]

On top of the solid floor, I will have 25mm Celotex insulation under 8mm laminate

That's very thin. Celotex advise using 20mm of t&g chipboard over the insulation. 8mm laminate may not spread point loads enough to avoid crushing the insulation. It would be safer if you used battens, but that's more work and also reduces the effectiveness of the insulation.

Can you not raise the floor level?

I understand that some of these problems could be solved by soldering copper but I have neither the tools nor skills.

The tools consists mostly of a blowlamp, which is not exactly expensive and can later be used for crème brulée.
The skills can be learnt by watching some you-tube videos and then practicing.

 

[John D v2.0]

I know it's not a direct answer, but to be honest for ultimate neatness it's worth considering a very short drop of 10mm speed fit chased into the wall and run behind the radiator. That's what I've done, you can get around 1.5kw out of 10mm pipe and s long as the drops are short it won't create much resistance in the overall run.

 

[Daniel123]

That's very thin. Celotex advise using 20mm of t&g chipboard over the insulation. 8mm laminate may not spread point loads enough to avoid crushing the insulation. It would be safer if you used battens, but that's more work and also reduces the effectiveness of the insulation.

Can you not raise the floor level?

Very good point. I might consider 12mm laminate then. I should probably ask this question in another thread.

I'd love not to raise the floor level but I am replacing carpet with laminate downstairs, and laminate on its own will be very cold. I am trying to make my home more efficient.

The tools consists mostly of a blowlamp, which is not exactly expensive and can later be used for crème brulée.
The skills can be learnt by watching some you-tube videos and then practicing.

Absolutely, and if I find this to be the only option I will go for it.

 

[Daniel123]

I know it's not a direct answer, but to be honest for ultimate neatness it's worth considering a very short drop of 10mm speed fit chased into the wall and run behind the radiator. That's what I've done, you can get around 1.5kw out of 10mm pipe and s long as the drops are short it won't create much resistance in the overall run.

I agree your solution would be even neater but to be honest I don't want to chase the walls, and also one of my radiators is 3kW.

 

[John D v2.0]

Wheni say chase the walls, you basically only need to chase the plaster. I had to split the radiator into 3no single panel radiators to meet the heading load for the room.

 

[Daniel123]

Wheni say chase the walls, you basically only need to chase the plaster. I had to split the radiator into 3no single panel radiators to meet the heading load for the room.

Indeed, would probably need to chase the plaster only. I should consider this option. Don't want to split the radiator though!

 

[Daniel123]

That's very thin. Celotex advise using 20mm of t&g chipboard over the insulation. 8mm laminate may not spread point loads enough to avoid crushing the insulation. It would be safer if you used battens, but that's more work and also reduces the effectiveness of the insulation.

Thank you again for noting this; I created a new thread 'Laminate on top of Celotex' to discuss whether it is feasible to put laminate over Celotex.

 

[Daniel123]

An update. I will not have an insulation under laminate (except for a fibreboard underlay), hence I will have to drop pipes from the ceiling. Not the most elegant solution but it's cheap and easy to do.