Honeywell HE280 problem: blowing up transformers on brand new unit

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Old 01-08-17, 03:42 PM
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Honeywell HE280 problem: blowing up transformers on brand new unit

Arg. Yano how you get this idea you should help your spouse out because the air is too dry and causing nosebleeds and your existing whole house humidifier is Dead with a capital D, so you go get a new one, spend the hours to do the install and troubleshoot, only to have the brand new transformer on the brand new humidifier unit blow up and let the magic smoke out?

(Long sentence. I know. Long afternoon, too.)

Got the new unit today, and HE280. Got it home and found I'd have to adjust duct work hole sizes, but whatevs. Gave me a chance to show my son about tin snips and HVAC; a little at least.

Got everything wired up, but no water is flowing. This system uses a push-connect water line input at the unit, so I was able to confirm there should be water (not removable = under pressure). I used a voltmeter to confirm power supply voltage, humidity switch functionality, and even that the humidifier electronics (pressure switch related?) changed state depending on furance on/off.
However, it still wasn't working.

Then the magic smoke smell... from the furnace!!!! Darn near freak out time: don't kill my furnace for this new humidifier!!!

With enough checking (and ASAP shutting off of the new humidifier), I find it's the transformer that's stinking. I'd tried using the already wired transformer (yes, I checked the specs first; they matched). What the heck.

OK, pull it off (it was hardwired through input power in the furnace, not via a controller board power source or the like). Put on a 4 way box since that's all I have in the house in spare parts, check that all's well with "normal" AC power. Voltmeter says, Yes, All's Well.

Plug in the new power supply from the HE280 kit and double check: yep, all should be well.

Still no water.

I figure I'll give it a bit and check back: maybe it's just patience that's required.

Couple minutes later, I hear a pop and the furnace shuts off, I quick look over and see a plume of visible smoke coming out of the new transformer. It's toast and blew the circuit breaker to boot.

Looks like I'll be taking it back off the furnace, trying to box it up, and swapping it at Home Depot. I talked to a (not electrically experienced) manager who first wanted to blame the old transformer, but I know *way* better than that. (24VAC is 24VAC no matter the source.Current capacity on the old transformer was 12A & new one 10A.) He backed off to just "if you bring it in and we have a replacement, we'll try to make it right." But I'm still grumpy: I spent nearly 4 hours installing and trouble shooting and now get to take it off and do parts of it again. Not what I had in mind...

Since the unit seems to be complete toast, this post is more of about (1) seeing if people have ideas about what might have happened or I could have looked for in the first place, and (2) as a reference for other people who go searching so they can find info I couldn't.

Any ideas? Is there a circuit I could have checked for continuity that I didn't? Comments welcome.
Thanks in advance!
Nate
 
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Old 01-08-17, 03:58 PM
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Welcome to the forums.

You don't use two transformers together.

In order for me to help you you'll need to tell me what you've done.
What are you using for a humidistat.
How did you connect to the furnace ?

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Old 01-08-17, 06:02 PM
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Thanks for replying!
I used one transformer; never 2.

I aimed to set it up exactly according to instructions (which happens to be the logical method, imo): unit on supply side, ductwork to intake side. Humidistat (as supplied) attached "upwind" of the ductwork from humidifier to intake. Electrical circuit exactly following the diagram, even to having the wiring head to the unit first, then continue the routing to the humidistat.

I never did check any method of seeing if I could trip the water solenoid directly (manually), so I'm struggling to narrow down inside the unit's electrical "stuff". But since I exactly (and double checked-ly) followed the electrical circuitry to hook up the unit...

Other than manufacturing defect, I'm really not sure how it could have shorted out so strongly. My initial google search revealed only this site with even commentary on the unit (from 2014), so I thought I'd take advantage of a collective's know how, if possible. But I'm really lost. :/

Any thoughts on how to go about further checking the functionality of components of the unit's electronics? Maybe it shouldn't be near-zero resistance when "on" (um... yah, that'd be shorted, right? Um...), but any suggestions on where/how to check different aspects of the circuit?

Thanks again for help. Like I mentioned, this is pretty much unmentioned anywhere but here, so.. Thank you a lot!
 
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Old 01-08-17, 06:08 PM
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Although I am a big Honeywell fan....I don't like and don't use their humidifiers.
I use only Aprilaire units.

The transformer, the humidistat and the pressure switch/solenoid are in a series loop.
If there is no visible short in the wiring..... that leaves the pressure switch and the solenoid.

Check the resistance of the solenoid valve.
 
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