Honeywell DT90E Loud Clicking With Timer Off

[zom414]

Hi there, I recently changed my Potterton PRT100 to the DT90E after reading some threads on here about the wiring etc. Term 1 to A and Term 2 to B with the neutral capped off.

It all seems to be working although I do get quite loud clicks when the timer is off, not a constant clicking like mentioned in another post on here but several an hour. The old thermostat never did this so just wondering if this is normal or is the unit faulty? I put new batteries in when I installed it too, I've even tried a rubber washer on the wall but it's still quite loud.

 

[JonathanM]

The DT90E thermostat is known to make a loud click every time it calls for heat. Others have posted about that, and I also have a relative with one, so I know from personal experience. Often it will do this every ten minutes, because of the way the thermostat works.

I would imagine it still calls for heat, even when your time clock is off, and that this is what you are hearing. A message on another board says the same:

https://www.plumbersforums.net/threads/honeywell-dt90e-thermostat.39944/

The stat will click on and off overnight, but this will be ignored as the programmer is off. The same thing would have happened with your old mechanical stat, i.e it would have been calling for heat, but it wouldn't have been so apparent.

The continuous clicking appears to be a different issue. According to Honeywell, that can happen when the neutral has been wired in by mistake.

https://support.resideo.com/s/artic...-click-continuously?sc_site=UK&language=en_US

The DT90 is a 2 wire volt free thermostat and the installation may have had the neutral connected by mistake causing it to click continuously.

 

[gas112]

nothing up with it thats what they do its the stat making and breaking as temp rises and falls regardless if heating is on

 

[Mister Banks]

I had a Honeywell DT90 (not an E) for about a week. The regular and loud clicking drove me mad so I returned it. I then tried a Honeywell T3, same loud clicking so also returned.