Humidifier Relay Going Out

[DRP6833]

I'm looking for a sanity check with the humidifier on my new furnace.

The furnace was installed this past summer. When I started up the humidifier (an existing steam unit, not new with the furnace) it worked for three days then quit. The service tech came by and found what looked like a loose connection on the relay. He fixed that and it worked once; when the humidity level got up to the set point it shut off and did not work again. Another service call, this time the tech replaced the relay. Again, it worked for a while but quit before it got to the set point.

Over the weekend I verified that I have 24V going to the relay when the thermostat is calling for humidity. If I short the output terminals of the relay the humidifier kicks in. It appears to me that the new relay isn't working.

I called the company this morning for another service call. Any idea what might be causing this? To work once then die seems strange to me. The tech told me last time it was a problem with the humidifier and it needed to be replaced, but I am convinced it's a problem with the furnace controls.

 

[Phantomd]

current going to the relay may be low?
Relay is a 24v, and ac/dc is proper?

You said a steam humidifier, I assume this relay is turning on a heating element, is the heating element pulling too much current (shorted) and burning up the relay?
Every time I have seen a "loose" connection on a connector its been because it got too hot or was physically damaged, I would suspect too hot in your application?

 

[HICKS]

How old is this steam humidifier?

 

[DRP6833]

Phantomd, the relay is just providing an open/closed signal to the humidifier to turn on. There's no current draw through it. The relay is part of the furnace itself, not something I installed, so I'd hope it would be correct for the application.

The loose connection was pretty obvious - when he moved the wire you could hear the relay clicking in and out. He didn't have a relay with him at the time or he would have replaced it then, we were hoping it was just the connection but apparently not.

 

[DRP6833]

Hicks, it's going into it's sixth season. I know they don't last forever but if the relay works it turns on and functions correctly. The relay doesn't close even if the line to the humidifier is disconnected.

 

[HICKS]

What make and model is it?

 

[DRP6833]

It's a Honeywell Truesteam, not sure of the model number but it's a 6-gallon capacity.

 

[BillK]

Sounds like a bad relay again to me. Was the relay actually part of the new furnace or something they installed because they knew you had the humidifier ? I might be wrong and I have only done three furnaces in my life but none of them had a built in relay for a humidifier.

Wonder if the relay just isnt up to the task or is wrong for the operating voltages involved ? Are there any numbers on it ?

 

[DRP6833]

BillK, judging by where and how it's mounted I'd say it was an add-on by the installation crew. It's mounted with two sheet metal screws to the blower housing, and it looks like a quick-and-dirty job. I'll have to take a look at it tonight to see if there's any numbers or anything on it. I would think they would have installed something up to the task, but you never know.

I haven't heard back from the tech yet (it's been two days). They may have contacted the furnace manufacturer Lennox for input.

 

[brewchief]

What model furnace? Different models have different controls and can be wired differently.

Sent from my SM-G965U using Tapatalk

 

[DRP6833]

BillK, I didn't get a chance to get the exact model of the relay, but it looks like one of these.

brewchief, I don't have the model number handy. I was able to find the installation manual for it on line; per the wiring diagram a humidifier control relay is wired to the H and C terminals. This provides a 24VAC signal whenever the system calls for humidification. I confirmed that's how mine is wired up.

Still no response from the installers or the service tech.