Wet UFH - TilersForums.com

[Andyw]

I am not sure if this is on the correct section but here goes.

When this is tuned after tiling you are supposed to run at a minimum temp and gradually increase over the week. My question is how is this done. Right now the manifiold is set to the lowest temp which is 35c. The ambient room temp is only 11c. I I set the stat to say 15c the UFH will constantly switch on and off. If I just run the UFH the room will get to about 22c. Or do you use the floor probe to set the temp??

 

[SJPurdy]

Thats a very good question that i hope you/we get a comprehensive answer to. I for one would like to check that the plumbers have set it correctly, on too many jobs I've seen the manifolds set far to high straight away and then the builders wonder why the tiles crack.

 

[Mark S]

Indeed a good question
The system should have been installed to be fully functional, ie set to operate at different temperatures. The water temp is controlled via a thermostat in the manifold that blends cooler water, which is on return with hot water to meet the thermostat requirements. If the water flowing through the pipes is not raised gradually, 5 degrees per day from ambient room temp, the screed will crack from thermal shock.
The system should be 'flexible' in the range of temperature that the water flows through it. Ideally you want app.27 degrees at the screed surface as a max.

 

[thompsonbrown]

There are a few things you should know before touching any underfloor heating.
Hopefully your commissioning engineer showed you the system basics.
Have a read through the manuals left with system if your not 100% sure.
You should find how to adjust the temp stat on the manifold to increse floor temp.
The room stat controlls ambient air temp not floor temp on most systems, so check to see if you do have a floor probe fitted.