Is dimmers more reliable than switches/relays?

I’m looking at replacing my heat controlling units from TRVs to termal actuators.
I have been sitting on the bed right next to the radiator trying to dim the termal actuator with a PWM dimmer, I have not yet concluded if it works or not but it got me thinking.
I have had so many relays/smart plugs break on me, but not a single dimmer has broken yet.
Are dimmers more reliable than smart plugs?

The cost of a Sonoff D1 vs a Zigbee smart plug is about the same.
The benefit of the smart plug is that it’s not wifi and will strengthen our ZigBee network.
The only positive side of the Sonoff is that it’s a dimmer, if they last longer.

Is it just me or are dimmers more reliable?

Field-effect transistor commonly used by dimmers have the advantage that they are not prone to mechanical wear like relays :bulb:

We got more relays than dimmers/(mos)fet switches but none of them failed the last 5 years so can’t tell a difference. :arrows_clockwise:

So there probably is some truth to what I have experienced.
I’m amazed you have not had a single relay fail on you

The only relays that have failed on me have been in my old Insteon switches that were prone to dying on power outages. Apart from that, and considering I have a number of relays in one form or another across the house, I’ve only had a few oddball cases where some outlet or switch relay failed (and likely it was something else anyway). I tend to not buy the super cheap Chinese stuff, so that may be part of it.

Anymore, I almost always buy dimmers since they can do both while switches can only do one thing, and I end up with FET’s instead.

I would like to help, but what is a “termal actuator”? I thought you meant “thermal”, but you used the term twice. If you post the device specs or a link to the device you may find more help here.

You can have a look in my own thread


It’s pretty much the same as a TRV but without all the smart bits.
You just command it on or off and it just does so. No fuzzing about with schedules, heating mode,. temperature sensor.
Just on or off.
It was spelling.

That’s what I thought it was.
To answer your original question- NO. You can’t use a dimmer to control a binary device like a relay or solenoid. You may damage the dimmer if you try.

As I read the specs, the slow opening and closing is internal to the valve. I’m not sure what you are trying to do, but I have seen a PWM-controlled ball valve. If I can find the link I will post it here.

If you look at the PDF in the other thread.
I’m trying to do the same thing they did, control the heating inside these devices.
As I have understood these devices, there is something that is heated and when it gets hot enough it opens the valve.
But if we can balance it on the edge where the heat dissipating and heat generated inside it is the same then we can set the valve at a percentage open.
I couldn’t get it set to that with the manual PWM that I bought.
But setting it to full on is not such a big deal, but it would be nice to be able to control the valve position with these