Commissioning under floor heating - Tile Advice

[rj1882]

Good evening. Could someone kindly give me an idea of the process of commissioning water fed under floor heating which has been set in sand and cement screed. It’s fully dried and is ready to be commissioned record I may it and tile it.
I’ve got some knowledge but it would be great to gain some more knowledge. Least of all so I can show the builder in black and white the process

thanks in advance

 

[Old Mod]

Starting at its lowest setting of ambient temp approx 15°
Start to increase temp to max at a rate of 5° every two days until maximum is reached.
Hold for 48hrs and decrease till back at ambient temp at the same rate as you took it up.
it takes a couple of weeks normally.
Then leave off for 24hrs before tiling.
Others say 5° a day, from what I’ve learnt over the years, a rate of 2.5° a day is preferred.
There will always be different opinions on a matter like this, but as an average, it seems to be the safest route.

 

[rj1882]

Thank you for taking the time to reply. I was thinking along the same tracks but just needed someone else’s opinion. Thank you.

 

[Dumbo]

The fact youre having to show your builder bothers me , this makes me think he is tiling it and didnt want to commision correctly .
If this is the case what else is he going to do wrong , does he have the skill set ,
Hopefully im wrong but if not please get a tiler

 

[rj1882]

Hi. Thanks for the reply. I’m tiling it but just. Had to explain why this needs to be done. I know many builders that look in shock horror when you tell them the floor needs commissioning lol

 

[Ajax123]

Pretty much as 3fall says above. However you will not be able to start as low as 15C as the temperature needs to be set at the manifold and the room stats over ridden somthat theh dont cut in and out in order to give a constant flow temperature. Your manifold is likely to start at either 25 or 35C. I would normally say max 5 degrees per day after 3 days but with sand cement slower is better so not going to argue with 2.5C per day. Once the process is complete it can take up to 48 hours for the screed to properly cool down.

Once complete a moisture Test is recommended prior to priming and tiling.

 

[rj1882]

Thanks for your reply. Pretty much what I though and told him.

 

[hmtiling]

If you're planning on using ditra/durabase or any other membrane which offers vapour equalisation then the moisture doesn't matter but the commissioning process is still vital