Hi everyone,
I wonder if anyone has any experience with evaporative cooler controllers out there?
This is for my own house. Dial makes a neat programmable thermostat (line voltage) to run an evaporative cooler. Problem is they seem to go belly up after about 30 days. I just bought my 3rd controller in as many years. But before I put it in I'm trying to take precautionary measures.
I wondered if this failure might be caused due to either voltage spikes, inrush current (3/4 hp motor) or heat inside the controller (mounts into a single gang cut in box).
I talked with a HVAC guy who said he has one going in his house for the past 5 years, without a glitch. But he has replaced several in one year in a customers house. He mentioned that these seemed to fail when there were power outages.
Makes sense to me, so I installed a Surge Arrester Circuit Breaker in my Panel, thinking this might take the spike out of a utility start up and maybe saving my controller.
I also am installing a wiremold extension box over the single gang cut in box with the hope that this might give a little breathing room for the electronics.

My question to sagacious sparkies:
What da ya think? Should this do it?
I've also considered putting a contactor on downstream, but what a pain in the a**!

I'd appreciate any input.

Thanks,
Brian

Brian,
It sounds to me like the controller is being overheated and you need more air circulation around the internals of the controller.
Is the controller electronic by any chance?.
Or have a micro-processor chip?.
The Surge Diverter is a darn good start, voltage surges before and after outages can cause all sorts of havoc with electronic equipment.
The installation of a downstream contactor is also a good idea, as the controller will only be carrying the control circuit current, just keep the contactor away from the controller to prevent any problems with stray magnetic fields.
Hope this helps!.

Thanks Trumpy,
As noted in my query, I mentioned that I will be mounting the controller on an extension wiremold box, figuring that would get rid of any possible heat problem.
As far as the possibility of a contactor installed downstream...I think I'm gonna figgaaboutit! It would be a trip into the attic in summer again plus some $$. I think the whole house surge arrestor will take care of any voltage spikes (hope so). Out here in Colorado the utilities like to roll off power periodically. I'm hoping that my installation will protect any sensitive electronics from fryin'. And oh yes, this is a digital controller.
Thanks for the input!

If all else fails put a contactor or a relay at the cooler.

Does the failing controller have mechanical contacts to switch the motor—or is it 100% solid state, using a triac? No doubt the controller’s horsepower/locked-rotor ratings exceed that of the motor.

On surge protection, be certain it is installed per the instructions. Longer-than-specified leads can easily make the device useless, regardless of its price tag.

Hello From South Dakota!

Brian, I see that you are in Lakewood. You arn't on IREA are you? I used to be from Colorado and have some of the same problems with IREA power.

Your surge arrester should take care of most of the problem. I never had that problem with Colorado Springs public utilities, but I could fry almost any electronic control in a matter of weeks on IREA.

Hope that helps,

Jon

Thanks for all your replies guys,
To Vickery: Sounds like a good location for the contactor or relay. I'll install one as a last resort though.

To Bjarney: I assume its a triac since the packaging is pretty small, it has a LED display and the literature says digital (no schematics). However, There is an discernible click when the motor engages...maybe a relay?
As far as the surge protector, I unraveled the supplied pigtail and connected it to the neutral bus per instructions...this does make me think of a grounding problem on a servo I worked on as an Avionics tech once though...the noise picked up that made it malfunction only went away when the grounding pigtail was shortened. hmmmm...

To njelectricmaster: No, I live on the front range which is all Excel Energy supplied. Usually IREA begins farther back in the foothills.

Thanks again for all your replies!

Brian the Sparkatrician

Brian, if the control has mechanical contacts generally they should be somewhat more rugged than a 100% solid-state version with a triac switching the motor. Triacs used to fail just looking at them cross-eyed, but they are getting better. If you can hear a mechanical click, the control probably has mechanical contacts.

The surge protector will be more effective is the pigtail is not curled or longer than to reach the busbar. For most effective line-to-neutral transient suppression, it’s best to keep the wire lead as short as reasonably possible.