Merry Christmas everyone!
I have noticed that the central heating thermostats are causing my monitors to restart. Immediately after the thermostat clicks, the monitors go black and restart a second later. I suspect this is caused by the back EMF generated by switching inductive solenoid.
I thought of adding some sort of snubber, maybe just a capacitor in parallel with the relay switch. However, I am not sure how much I will violate safety (and regulations).
Does anyone have any idea if this is a good idea? Or is there a better solution?
For more information I have attached the photos of the unit.
I have noticed that the central heating thermostats are causing my monitors to restart. Immediately after the thermostat clicks, the monitors go black and restart a second later. I suspect this is caused by the back EMF generated by switching inductive solenoid.
I thought of adding some sort of snubber, maybe just a capacitor in parallel with the relay switch. However, I am not sure how much I will violate safety (and regulations).
Does anyone have any idea if this is a good idea? Or is there a better solution?
For more information I have attached the photos of the unit.
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Is it gas or electric(heat pump or resistive)? The TStat is switching a 24VAC signal to the main system, which usually has a relay or contactor(heat pump) which is a big relay. Is it a new problem due to TStat new or a new system?
Do you have one thermostat per room and if so do all monitors restart or just the monitor in the room? Are your actuators 230V version? From the same supplier?
It would have to be a pretty big EMF spike to travel back to the breaker panel, then out to the monitors.... As a first effort, have you tried using a surge suppressor type power bar for the monitors?
Each room has it is own thermostat. The actuators are 230V and must be from the same supplier, but a different manufacturer (Möhlenhoff).
Both monitors restart (connected to a USB-C to 2xHDMI adaptor).
In these hydronic installations, the thermostats directly switch power to the actuators, which opens the water valve to each radiator in the room or zone. Depends on whether there is one thermostat per room or one thermostat for a zone or group of rooms the wiring may be different. It looks also from the PCA that this is a version that switches 230V line power directly and hence the X cap on the board.
If the OP uses actuators from the same manufacturer as the thermostats, then the OEM should have some guidance on how to wire them up to limit radiated disturbance. The thermostat should have been tested for CE compliance as part of the system.
If the OP uses actuators from the same manufacturer as the thermostats, then the OEM should have some guidance on how to wire them up to limit radiated disturbance. The thermostat should have been tested for CE compliance as part of the system.
If each monitor is connected separately with an HDMI cable, they are not affected. I suspect that the long cable is causing this phenomenon, which seems to act like an antenna. 2 monitors are connected to an HDMI to USB-C adapter and a USB-C cable runs under the table to the laptop.
Our posts crossed..
It looks like the thermostats is from the same German manufacturer then, as seen from the dissembled unit?
So both monitors are on the same USB-C adapter and do they restart no matter which actuators are turned on or off or just some rooms?
It looks like the thermostats is from the same German manufacturer then, as seen from the dissembled unit?
So both monitors are on the same USB-C adapter and do they restart no matter which actuators are turned on or off or just some rooms?
I am also surprised. The thermostat is from a reputable German company (although it has a cheap relay inside 😆).
Yes, both the thermostats and the actuators are from a company called Möhlenhoff.
I have found that it is only the thermostats in the immediate vicinity that cause this. Some rooms are a little too far away and have no effect.
If they re-start regardless of which thermostat is actuating, then what I might do is to solder an MOV across the relay contacts (that is going to void your warranty or you can try wiring that in parallel to the actuators connections but not going to be as effective.). Or try wiring one across 230V at the central heat exchanger where all the actuators are.
I keep posted after your relevant replies…
Then in this case I might try MOVs in the thermostats in the vicinity. Maybe wiring them in parallel to the actuator wiring connections would already be good enough but I suspect soldering across relay contacts would be the best option BUT there are warranty and safety consequences…
Then in this case I might try MOVs in the thermostats in the vicinity. Maybe wiring them in parallel to the actuator wiring connections would already be good enough but I suspect soldering across relay contacts would be the best option BUT there are warranty and safety consequences…
Also, the RFI could be a grounding missmatch. Be sure the monitors and computer are on the same circuit and ground.
I fitted two 16x12x8 high permeability ferrite beads to the cable as shown in the picture. I will report on the results. Thanks for the hint.
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The trick with the ferrite bead worked! When I turn the knob the relay clicks but the monitors are fine. Thanks all for your help!