Dampness around low level underfloor vents

Joined
30 Aug 2012
Messages
75
Reaction score
0
Location
Norfolk
Country
United Kingdom
Hello,
I've recently bought a house that was build about a year ago. It has underfloor heating (wet type, running off an air-source heat pump). The other day I noticed the low-level underfloor vents had water around them, as you can see in these photos.
The water does not smell of anything. The underfloor heating seems to work OK (now I've had the underlay replaced...that's another story!). The pressure in the system seems a bit low - just under 1 bar, but (I haven't checked lately) does not seem to be reducing.

So, does anyone have any idea what might be causing this dampness? My logic would suggest it's very cold air coming out of the vents making moisture in the air condense on the cooled stone slab. But the weather's very cold at the moment so it seems unlikely that air coming out of any part of the house would be so cold. The other option is that it's water vapour coming out - but where from? There are three vents along the back of the house, and they all have this weird dampness.

Could it be that running the underfloor heating is warming up the ground under the house, causing water in there to evaporate and come out of the vents, where it condenses? Surely that's a sign of ****ty insulation; I'm supposed to be heating the house, not the chunk of planet earth underneath it!?

Any ideas, anyone??
 
Sponsored Links
Joined
20 Nov 2018
Messages
5
Reaction score
0
Country
United Kingdom
The vents are there to get rid of damp air in the underfloor void. That air will be warmer than ambient because of the ground and the house above it. Warm humid air hitting cold paving slabs = condensation.
This.
 
Sponsored Links
Top