Turning on Underfloor After Tiling - TilersForums.com

[kiteboy]

Hi all

About to turn of underfloor heating a month after we tiled the kitchen floor - (its cold) but i gather this should be done slowly and gradually up to the working temp and then turned back down again too

Ive checked the control valve on the underfloor manifold and the lowest it goes too is 35 degrees which its set to now

Looking for any tips really as I cant go lower than 35 anyway

Thanks

 

[J Sid]

35 is good and will bring up floor slowly, make sure your wall sat is set low and not by a cold open door
will help to monitor with one of these

 

[kiteboy]

Argh I have one of them great - Ok - Ive set thermostat to 17 which is 1 above ambiant at the mo - its cold

 

[Tile Fix Direct]

Be careful if the screed is gypsum/anhydrite. If you turn the heating on and the anhydrite screed is still wet (the only way to check is for a screed test) then the remaining water in the screed could be forced out before the setting is complete which will cause cracking and reduce the strength of the screed and cause failure.

 

[kiteboy]

Im not too worried about the screen being wet - its been down 8months - thanks though

 

[Ajax123]

Be careful if the screed is gypsum/anhydrite. If you turn the heating on and the anhydrite screed is still wet (the only way to check is for a screed test) then the remaining water in the screed could be forced out before the setting is complete which will cause cracking and reduce the strength of the screed and cause failure.

WHAT!!! firstly the screed should have been checked before tiling commenced. Secondly the screed will be fully set regardless of any residual moisture present. Thirdly presence of any moisture or not wont affect cracking and finally turning the underfloor heating on with any residual moisture present will not reduce the strength of the screed. Too much moisture in the screed regardless of screed type can cause emulsification of primers and cause delamination of tiles...

 

[Ajax123]

Im not too worried about the screen being wet - its been down 8months - thanks though

so its had 8 months to dry out.... its also had 8 months to get wet... Screeds, regardless of type, should always be tested for residual moisture (%RH) before any tiling commences...

 

[Ajax123]

Argh I have one of them great - Ok - Ive set thermostat to 17 which is 1 above ambiant at the mo - its cold

you will only be putting water through at the 35 degrees C if the stat is calling for heat. if the stat is saying no heat please you will not be warming your screed. at 17 I would think it is not really doing anything.

 

[Tile Fix Direct]

Talking to BAL ref Gypsum screeds. If the screed is mixed with water in correct proportions that water is required for a chemical reaction. If that water is then forced out prior to the reaction being completed (i.e. the heating being turned on) then the gypsum screed will not reach it's full potential strength, and possibly fail.

 

[Dumbo]

I was under the impression that a gypsum sulphate screeds could have ufh turned on after a week to help dry the floor is someone going to tell me this incorrect .