This UFH system is in my mil's bungalow purchased earlier this year.
It has 9 zones, is run from a WB 37CDi combi, and uses Wavin actuators with a wall stat in each zoned room. It all appears to work just as it should.
A few weeks back, tho', one of the two bedrooms warmed up excessively - its wall stat was always set at around 15oC, and it all seemed to be fine. However, on this occasion, walking into the room was greeted by a wave of warm air, and the floor was also very noticeably warm. 'Clicking' the wall 'stat showed that the air temp was above 20o.
I removed the panel covering the gubbins (see photo), and I could see that the Wavin actuator was working just as it should, and would respond correctly to the wall stat, opening and closing slowly on demand. Since the valves were working correctly, and also because I couldn't see the issue being caused by a 'sticking' valve, I, cough, put it down to 'user-error' - perhaps Nan had turned it right up the previous night, and was only noticing the delayed response in the morn after having turned it back down? Anyhoo, all was well for a few weeks.
This morning, however, Nan tells us that the spare bedroom, with the wall stat always kept at min (~10oC) was hot, and 'clicking' the 'stat showed the air to be at 20oC. This is exactly what happened with the other bedroom. This really didn't make any sense - how could a zone come on that much by itself? Unless it's a built-in anti-seize feature, perhaps? Is it designed to open up zones at random if they aren't being used?! If not, what on earth else could be causing this?
Or, could the UFH be soooo 'effective' that when the wall 'stat came on (due to the room being cold enough), it then overshoots in temp by that much?!
Thanks :)
PIC (ignore yellow circles. Does that top wiring centre unit have an anti-seize timer in it?)
