UFH behaving oddly

[WWilts]

New build in progress,

UFH 4 zones, the kitchen/family room zone has 3 circuits.

Set thermostats to 21c. Kitchen/family room went to 24c. One of the 3 kitchen circuits stayed warm constantly.

Why? Electrician says no problem with the thermostats or connections. How to solve?

[PeterW]

What controller ..? And what actuators ..? Remove the actuator off the misbehaving circuit and see if it’s still warm as it would point to a duff valve

[JohnMo]

Sounds like you have the flow temp set too high.  The floor response is such that you are overshooting the thermostat.

 

How thick is the insulation and screed, what flow temp?

[ProDave]

8 hours ago, WWilts said:

One of the 3 kitchen circuits stayed warm constantly.

So that zone is not switching off.  Perhaps that actuator is wired to the wrong zone or it is simply not screwed down onto the manifold properly.

[WWilts]

9 hours ago, PeterW said:

What controller ..? And what actuators ..? Remove the actuator off the misbehaving circuit and see if it’s still warm as it would point to a duff valve

Hetta system

[WWilts]

1 hour ago, JohnMo said:

Sounds like you have the flow temp set too high.  The floor response is such that you are overshooting the thermostat.

 

How thick is the insulation and screed, what flow temp?

100mm Celotex 

50mm liquid screed

Flow temp was 50c

Turned flow temp down to 35c, kitchen zone stayed at 21c with thermostat set to 22c

Now flow t set to 40 to check response

Edited December 10, 2022 by WWilts

[Alan Ambrose]

We had this problem with one circuit on a new Uponor system. Was simply the actuator for that circuit not clipped on properly - from memory they just clip on, but the clip action is quite hard. The actuator movement is only a few mm, so it doesn’t take much.

 

Take actuator off, check it responds to the thermostat signal, check that the valve moves by poking it with a pencil etc., re-install actuator carefully making sure it is fully clipped on.

 

if actuator doesn’t move with thermostat, check wiring and, as last resort, replace actuator - they’re only £20 or so. You can also swap the actuators from one loop to another as a debugging measure - to prove which actuators / valves work and which don’t.

 

Alan

[WWilts]

On 10/12/2022 at 08:35, ProDave said:

Perhaps that actuator is wired to the wrong zone

Yes, the problem circuit in the kitchen was connected to the porch thermostat in error.

Sorted, the kitchen (3 circuits) all now cut out at the desired temperature.

But new problem uncovered: porch UFH stays cold no matter what. Can feel it with back of hand, stone cold. Set the porch thermostat to 18.5C but the porch temperature remained at 15.5 no matter what. Even with the water mix temperature for UFH turned up from under 40C to over 50 C.