Optimising wet underfloor heating temp

longwalks1

We've just had our Wunda underfloor heating connected up and are slowly increasing the temperature so not to crack the tile adhesive/grout by whacking it up to 'max' straight away.  The TRV on the UFH manifold is set at 45 degrees.  Been told to increase it gradually over the next couple of weeks until we are happy with the room (floor) temperature.  

Does this mean if i set the room stat to, for example, 22 degrees, there's a chance it wont ever reach it as the UFH manifold is stopping calling for hot water once manifold temp reaches 45 deg?  Just trying to get my head around it

ComicGeek

What is the maximum design flow temperature for the UFH, set by the designers? You shouldn't be overriding that as it can damage the floor, and definitely shouldn't be increasing it 'until you're happy'!

Has there been a heat loss calculation for the area, and a proper design of the UFH to achieve this heat output? If so, then there will be a design flow temperature specified and you shouldn't go above this. If there hasn't, then again you shouldn't really go above 45 degrees without proper advice.

Is it in poured concrete screed, or panels laid over the existing floor with latex screed/tile adhesive over the top? That will affect maximum flow temperatures, as well as affecting how long it takes the floor to fully dry out and the UFH to fully respond.

Do you have a remote sensor thermostat measuring the surface temperature, as well as room thermostats measuring air temperature?

In answer to your question, the room should reach 21 (which is the normally design temperature) degrees (eventually, as UFH systems take time to warm up) IF the UFH system has been sized correctly, and at the design manifold flow temp (whatever that is).

I really wouldn't increase the manifold temperature at all - in fact, I would personally be turning that down to 35-40 while everything dries out. The lower that temperature the more efficient it will run, so worth seeing how low you can turn it and still be comfortable.

longwalks1

Hi ComicGeek.  Many thanks for your reply, makes complete sense.  I searched and Wunda max flow temp is 45 degrees.
No heat loss calculation was done, and its laid in foam/foil panels (almost like Kingspan panels) over the existing concrete floor, then tile adhesive and tiles on top.
Max room temp on the app is 21 deg, and the spec of the system was given to me by Wunda.
I'll drop the manifold TRV to 40 degrees and see how it is then