[pattyobrien3]

So, my whole home humidifier that I installed about 3 years ago hasn't worked in about 6 months so I thought the apocalypse would be a good time to work on it.

I'm a bit stumped, so I was hoping someone would be able to point me in the right direction.

First, I checked the water supply. It's on and works. I took off the brass water valved and soaked it in some CLR to try and remove mineral deposits if any were there.

Still nothing.

I got out my E-meter to check contunity / voltage to the various components, and here's what I got.

Power at transformer: good, 120V.

Power at pressure switch: same.

Power out of pressure switch: None.

Power at solenoid: None.

Since no power was coming out of the pressure switch (while unit was running), my first thought was to replace it, which I did and it didn't do anything.

My next thought is to replace the solenoid, but since I'm not getting any power out of the pressure switch, I'm not sure how/if that could help. If the pressure switch isn't being triggered, it's not sending a signal for power to the solenoid, so a new one wouldn't make any difference.

It's a bit annoying, I put it all in and worked fine right out of the box, and I don't want to have to get a whole new unit, but also don't want to keep buying replacement parts which may or may not do anything.

Anyone have any advice? I have also attached a picture of the disassembled components with notes.

Other notes:

I noticed the voltage out of the transformer was 120V, but the label on top of the pressure switch (where the wires from the transformer input) say '24VAC' in. That seems like a problem, but do transformers go bad?

Also, I hooked the power leads from the transformer directly to the solenoid to bypass the entire controls system, and it vibrates and makes a humming noise, but does not allow water to flow. This makes me think that the solenoid might need to be replaced too, but it won't matter if there's no voltage coming out of the pressure switch, right?

 

[roughneck]

You’d first need to find out why the pressure switch isn’t closing.

 

[pattyobrien3]

Right, my first thought was to get a new one, but that didn't work either. Tried straight-up blowing into the pressure switch instead of relying on the static pressure from the air movement but that didn't work either.

So, I'm not sure. Presumably, I should get some voltage out of it once air is moving if it's working, right?

 

[user_12345a]

If the humidifier got 120v, the pressure switch and solenoid are probably cooked.

the pressure switch and solenoid likely cost as much as a new humidifier.

personally if just the pressure switch is bad i would just bypass it and wire the humidifier so it's only energized during a call for heat. it's unnecessary in most applications.

most furnace control boards have humidifier terminals - some are 120v and need a transformer, others are straight 24v.

diagnose with your meter, not by changing parts.

 

[pattyobrien3]

This one seems to require 24V into the control system, but the voltage I'm seeing out of my transformer is 120V. Do transformers go bad?

 

[user_12345a]

transformers can go bad but not normally in a way that would cause the secondary coil to put out line voltage.

 

[surferdude2]

What type of meter are you using to measure the voltage and can you give the voltage from both sides of the transformer. The primary should be 120 vac and the secondary 24 vac. You obviously have 24 vac since you stated that you jumped the 24 volts directly to the solenoid and it made a rattling sound but did not open. That doesn't surprise me since the solenoid is clearly marked as a 24 vDC solenoid. I doubt it did any damage to have AC connected, so not to worry. You just rattled its cage a bit.

Now, it would be helpful if you would put your volt meter on DC voltage and measure the voltage across the pressure switch terminals. Do that under both scenarios... blower running and blower off. On that particular system, we would ordinarily expect to see 24 volts DC when the blower is off and zero volts when the blower is running.

Blowing directly into a new pressure switch will definitely cause it to close so perhaps you didn't actually measure the resistance across the contacts but instead may have had your meter set on AC volts whereas there would have been DC voltage across that switch when the fan was not running. I suspect the pressure switch is ok. Indeed the DC voltage supply may have failed and that may be the root of your problem. Measuring DC with the meter set for AC won't normally give any reading on a quality meter using capacitive coupling for the AC scales.

As an aside, obviously the humidifier has been modified to run on DC voltage for some reason. Probably some digital control via a wi-fi hookup but that's just a guess... you can enlighten me on that. It will be helpful for know where the DC is being sourced from so we can see if it's up and working properly.

EDIT.. If you are actually running 120 VAC to the 18 gauge stat wire as indicated in your picture, it's beyond unusual to say the least!! Please verify the accuracy of that label. If true, it could indicate a failed rectifier diode in the DC power supply that is passing 120 VAC through but at a high impedance source so that it didn't damage anything downstream. A high impedance source voltage will virtually disappear when a significant load is connected to it. We need to trace back to that DC source supply and check it out. It's looking like the root cause.

 

[user_12345a]

i don't know of any humidifiers that use a dc solenoid.

 

[surferdude2]

i don't know of any humidifiers that use a dc solenoid.

Me neither but this one has been modified to use DC or else someone has replaced the solenoid valve with the wrong type??? (possible). It may well be that the DC source has failed and improper voltage readings have been misleading or maybe it just needs the right type valve. lol

It would possibly be using TTL or SCR logic. More info from the OP is needed.

 

[surferdude2]

If that's actually 120 POCO transformer voltage (low impedance), that's a genuine death trap situation if care isn't taken when some unsuspecting tech gets involved or the OP gets careless.

 

[Fergiejr]

Hi guys, I have the same model and this definately is a DC solenoid. Honeywell HE280. My valve is failed and I can't find the proper replacement - every site suggests the AC valve for a 260 unit. It's getting frustrating.

Just venting.

 

[Markkkkk]

Hi guys, I have the same model and this definately is a DC solenoid. Honeywell HE280. My valve is failed and I can't find the proper replacement - every site suggests the AC valve for a 260 unit. It's getting frustrating.

Just venting.

They have on Amazon. Not cheap though. Just bought some. Dc not ac. Supply house guys keep offering me universal solenoid and valve. I keep telling it’s DC but they looked at me like I am crazy so I gave up.
On Amazon’s it’s $80 so not cheap. Just search on Amazon’s dc humidifier solenoid

 

[Markkkkk]

Dc solenoid