Radiant zone no longer calls for heat

adobelb

Forgive any mistakes in terminology as I try to describe my system.

I have a six zone radiant system, with a remote manifold that covers three zones, all plumbing and electric were professionally installed about two years ago during a complete renovation. Everything worked fine until recently one of the zones in the remote manifold no longer responds to the thermostat's call for heat. There is a Uponor zone control module in place that works for the other two zones. In those zones, when the thermostats call for heat, a red light goes on (which says thermostat on the Uponor unit), followed by a yellow light (which says actuator). I can hear a manual click as the switch underneath the actuator (? rectangular metal box) is triggered. But in the case of the zone that no longer is responding, the red light goes on, but there is never a response from the actuator, both in terms of physical moving of the switch or the yellow light going on.

Possibly the cause of the problem or maybe just coincidental: around this same period the thermostat for the non-working zone was flashing a low battery warning. It's one of the very basic Honeywell programmable thermostats. I replaced the batteries and snapped it back in place, checking that the wiring was still tight (just one red and one white wire). On the Uponor unit, the red led flashed for awhile then remained solid, again with no effect to the actuator. I then switched out the thermostat with an even more basic non programmable Honeywell, including the wall plate with its basic wiring. The results were the same.

I should mention that the zone is my wood shop, so the thermostat (but not the manifold) is in a dusty location. This is partly why I thought about swapping out the thermostat and sprayed it all out with compressed air.

I remember my plumber once showing me that the zones could be manipulated manually by switching that lever beneath the actuator. I thought of this as a temporary solution at least, because I use the shop for work and some activities like finishing and gluing are temperature sensitive. However, when I try to pull that switch it moves over slightly, but hits something that prevents it from going all the way to the right, and I have not wanted to experiment much more without further guidance.

I don't know if this is a problem for an electrician or plumber, or if it's something I might be able to troubleshoot without calling in someone else. Any thoughts are much appreciated!! Thank you.

(In this image the non working zone is the third one, marked M bed. I took the picture when the E Bed zone was active)

STEVEusaPA

Professional installed, you say? Why not have that person come out to repair. They would have the most knowledge about your system.

Ironman

It sounds like that zone valve is bad or has something stuck in it. The guts can be replaced without removing the valve body, but it needs to be isolated from the system.

Is that something you could do? IDK since IDK your skill set, knowledge or ability.

adobelb

Yes, I think the zone valve is the problem. I tried the switch again and actually now it freely moves back and forth with no resistance either way, unlike the other ones which will kind of gradually retract from the manual open position unless slid up into lock.

From further research I see that others have a problem with this particular end switch: "The problem, as others have experienced, is gear slippage that results in the product's end switch not closing." Apparently it is not an option to replace just the end switch but maybe replacing just the power head would work, without doing anything to the mechanical part of the valve.

I will watch some videos and see if it's something I want to attempt... I work in construction but my plumbing background is limited so I might just call in someone, especially as I am discouraged a little by the warning sticker on the valve saying there might be more than one electrical disconnect. Original plumber is not an option, in reference to a previous comment.