Radiant Heat Overheating

MarieO

We have Wirsbo Radiant (quicktrak) in our kitchen with a Buderus Logano G115 with the Logamatic 2107 with FM241 module, installed early 2000s. The rest of the house is heated with baseboard. We have sporadic overheating since turning the boiler on back in November, maybe half a dozen times so far. For example, the room sensor/temp is set to 69/70 degrees in the past 24 hours I've seen the room heat up to at least 79 (and it takes quite a while for the temperature to come back down). We replaced the mixing valve sensor, but are starting to think the problem may be with the actual mixing valve itself. The outdoor sensor, room sensor, and mixing sensor appear to be reporting the correct temperatures. Ideas as to whether this might be a control problem or a mechanical issue? Of concern…we had a contractor in that put a hole through the pex this summer and then repaired it. Our plumbing and heating contractor that installed the system has passed away (my father). I think the actuated mixing valve is a ESBE, but there is no labeling on it. We're located in Central Massachusetts.

Photos attached:

Grallert

It's been a few years since I've had one of those apart but I think you're on the right track. Does the red/blue indicator change when the valve is moving? That actuator can get hung up allowing either too much hot or cold through. I think that actuator can be remover from the valve its self exposing the valve stem. Mark the location of the actuator and then mark the position of the stem after the actuator has been removed. Just for future reference. You should be able to move the stem/valve through it's range pretty easily.

hot_rod

You are absolutely correct it could be either or both, your father taught you well!

Maybe the pump is running when it should not be. Or a check valve is stuck with debris.

One quick attempt is to turn those red and blue handles where the gauges are, closed and back open. I think there is a spring check valve inside those.

Below is a pic of a different brand of the same type of valve, spring is missing.

So it is a shutoff, spring check valve (with manual bypass) , gauge well, pump union, iso valve, mounting tab on the back, and has the cross over function. Those clever Germans :)

When the valve is turned part way, 45 degree, the edge of the ball holds the check open. This was designed to allow thermosiphon in the event of a power outage or failed pump.

I have seen some debris get under the check, hold them open just enough to get a small "ghost" flow and over-heat the zone. Turning them from one extreme to the other when the pump is running may flush it clear.

Or it could be electrical in nature?

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MarieO

Thanks for the ideas.

I replaced the ESBE actuator with a newer ARA663 with the same results.  Both actuators were tested on an external 24v power source and rotate both clockwise and counterclockwise without problems (should have tested this first before buying a new one!). The valve also moves freely and easily so it isn't a torque issue.  

Broke out the multimeter and ran the mixing valve relay test. The actuator always works to open (voltage across blue wire and pin 44 reads 27.28v). On closing, it works intermittently (voltage across blue wire and pin 43 reads 1v or 22.6v, never 27v). The voltage from the transformer is always reading 27v. 

I suspect that there is an issue with the FM214 board so am reaching out to support for further guidance.

Here is a video of the test mode:

https://drive.google.com/file/d/1qjroNcQijje2yk5N88lHPwoXUXvjAfkX/view?usp=drive_web