Floor insulation for UFH reftrofit

[Radian]

Just thinking about feasibility of replacing our ground floor radiators with UFH. Floor construction is concrete beam and block, 50mm XPS, 18mm Caberfloor.

Would it be practical to chase out 50mm PIR to take pipes or is there a better option? Obviously precious little insulation but no way are we going to raise the floor levels.

Somewhat ironic that a suspended timber floor could be much more successfully adapted.

[markc]

The floor finish would be a better insulator than what’s under the pipes so nearly all the heat would be lost to the block and beam which would suck heat away

[JohnMo]

As much heat (or more) will go downwards as up.  Would not be very effective and cost huge amounts to run.

 

I would save your money to spend on something else.

[Radian]

Not quite beaten yet. Agreed the chipboard floor will be almost as good an insulator as what's underneath so how about Mapei Topcem screed on top and Spacetherm A2 aerogel below? R-value for 10mm = 0.5 plus 2.25 for 50mm celotex taking up the remaining space giving a total 2.75m2K/W or U-value of around 0.3

 

The reason I can't really just give up is that our main living room has little in the way of wall space for the larger radiators that would be required to switch from gas boiler to ASHP. Not without flanking a stone fireplace with a couple of rads. Just silly.

[JohnMo]

In the grand scheme of things, the aerogel adds can very little, compared to just using 60mm PIR.

[Radian]

2 hours ago, JohnMo said:

In the grand scheme of things, the aerogel adds can very little, compared to just using 60mm PIR.

 

OK,  0.022 W/mK for Celotex GA4060 = 0.06/0.022 = 2.727 compared with 2.75 above - you're absolutely right!

U-value = 0.366, over 25m2 = about 10W per delta K, e.g. 300W loss for just about the worse case scenario here by the south coast. (freezing ground, 30 deg. UFH)

Could I live with that I wonder.