Please help: Water running non stop to furnace humidifier

SparklingWaterDecember 1, 2012

Hello. I have an Aprilaire wall-mounted, furnace-connected with thermostat older model humidifier which was recently serviced with new PVC tubing and filter and was told all was "ok" by the HVAC man. Just yesterday the same company's plumber tightened up the top nut on the dedicated humidifier valve to solve some minor water leaking. The valve controls the flow of water to the humidifier and comes off of the gas water heater and no longer leaks at the nut.

I am disturbed by the amount of constant water entering the sump pump from the humidifier, even occurring when the furnace is off. It's not just a minor drip, but more like a considerable constant run drip. I don't think this is normal and wish your opinion. I can't even imagine our future water bill if I were to let this go unattended. I have a newer 80% dual stage American Standard gas furnace and realize water is a combustion by-product, so water would be more prominent when the furnace is running. But this humidifier water to sump pump is constant even without furnace on.

Is it normal for water to be flowing through a dedicated line to the humidifier even when the furnace is off? I can hear the water spraying through into the filter box no matter when.

Sounds to me like I have a faulty water valve problem or am missing some turnoff feedback which engages when the furnace turns off. I have once again turned this branching valve from the gas water heater off until I know what's up.

Thank you for any and all help. Cross post with HVAC forum.

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Model number of humidifier?

What controls the humidifier?

    Bookmark   December 2, 2012 at 10:59AM
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Sorry for delay and thank you for your interest brickeyee.

Aprilaire Humidifier model 760 flow through system. When HVAC was here in September doing fall furnace check he installed a new AA feeder tub ("NP OTP" on bill), saying the old rubber tube may have weakened and splayed at its end over the years and pose a water leak risk. He also put in a new water panel and #35 pad. There was no discussion of the Solenoid valve assembly nor of the water inlet orifice. No problem was noted on testing the humidifier except for water leakage from the gas water heater branch supply: the "saddle" valve controlling hot water supply to the dedicated humidifier line leaked. All was turned off until further investigation of this saddle valve.

Below are pictures of the water valve above the gas water heater: some say it is a saddle valve (which, as all or nothing" is not allowed I gather) and others, including the company's plumber say it is a turn valve. The company plumber tightened up the nut a bit on Friday and the leak seemed to stop. The system was turned on for test, but after the plumber left I noted the continuous water running to the humidifier, heard it spraying into the box and saw the constant stream from the outlet to the sump pump so I turned it all off again.

Here are key points Aprilaire owner's manual makes on the 700 models:

"The correct water flow is determined by an orifice equipped with
each drain type humidifier. When the humidifier is operating, there
will be a small, steady stream of water to drain, which flushes
away most of the trouble-causing minerals.

Do not use the saddle valve to regulate the water flow. It is designed
to be completely open or closed."

Here are some photos-sorry can't seem to resize them on PB:
to be completely open or closed."

Basically, the Aprilaire Humidifier looks like this and has separate humidistat on return.

Thanks for any advice.

    Bookmark   December 2, 2012 at 5:10PM
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The humidistat calls for humidity, and activates (opens) the solenoid to allow water to flow over the pad. Additionally, the furnace fan must be running.

The solenoid valve is being heald / stuck open - probably because of scale in the water. It's my guess you need a new valve.

    Bookmark   December 3, 2012 at 1:57PM
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Solenoid jammed partly open is a very likely cause.

They do not have that much closing force, and even a small piece of debris that gets to them can cause them to stay slightly open.

You may be able to flush the valve and line.

Any water heater is occasionally going to throw some scale particles.
You might need a filter in that line.

This post was edited by brickeyee on Mon, Dec 3, 12 at 14:32

    Bookmark   December 3, 2012 at 2:30PM
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Ok. Thank you both very much. Obviously over my capabilities, so I will call...a plumber or is it HVAC. I think a plumber.

But, I appreciate you helping me identify that the solenoid is probably stuck open (hence constant water run), possibly from water scale buildup and that a "flush" attempt first may work.

Any input on whether that's a saddle valve or not?

I am very appreciative of your help. Much to do in our house. Thank you.

    Bookmark   December 3, 2012 at 3:16PM
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Your humidifer is properly connected to your cold water line. It uses a soldered tee and shut off valve.

Years ago installers used to use valves that installed over the copper tubing, via a big U shaped bolt. The bolt held a "saddle" that the valve screwed into, and pierced the pipe. It didn't leak because of a rubber washer. It wasn't the proper way of doing it - but it was quick and didn't involve draining the water from the pipe. Eventually these valves leaked when the rubber washer dried out.

Your installion is top notch - no problems with the valve.

I would call an HVAC guy who installs April Air - he should have the parts (solenoid).

This post was edited by doug_gb on Mon, Dec 3, 12 at 17:06

    Bookmark   December 3, 2012 at 3:48PM
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Thanks again. That's what I will do.

    Bookmark   December 3, 2012 at 5:39PM
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And we have an answer: defective solenoid just as some of you thought. HVAC gentlemen spent lots of time here running a full analysis: furnace wiring (direct 120v), fan, intake orifice and feeder tube (just replaced), humidistat itself, water supply valve, and of course solenoid which turned out to be the problem. It wasn't closing so water ran through even without the humidifier current.

Finally I have a fully working furnace and humidifier. Yea! Feels like a long taffy pull since September is over.

Thank you ALL for your comments/ideas. Funny thing: when I called in the request order for an HVAC visit and suggested it might be a stuck solenoid based on conversation on a blog, she replied "you can't believe information from strangers"!

You aren't strangers, you're respected GWbers and friends. Thanks so much and Happy Holidays!

    Bookmark   December 5, 2012 at 3:03PM
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Glad it works. I just want to add, saddle valves are the spawn of the Devil. They look kind of cool, but they're crap and will fail/leak at the first opportunity.

There are so many cool slip-on compression replacements for them now, which are painless to fit.

    Bookmark   December 7, 2012 at 1:43AM
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