Model number of humidifier?

What controls the humidifier?

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:

http://www.aprilaire.com/themes/aa/en/manuals/Owners_%20Manua_Model_400_%20500_%20600_%20700_10006899.pdf
to be completely open or closed."

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

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Thanks for any advice.

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.

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

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.

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

Thanks again. That's what I will do.

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!

Hi, the HVAC guy was here last week to solve a problem of water running onto the floor from beneath the furnace & Aprilaire humidifier. Said the pump that drains the condensate pan needed to be replaced, (so the pan was overflowing). He replaced it. Now there is no water leaking, but the pump is running periodically, yet no water is coming out of the drain tube (into the laundry sink). Always before when the pump kicked in, water would run out of the drain tube. Seems like there is no water supply, but the junction where the water supply line comes off the main water line appears to be open (it is parallel to the line). Does this sound like a Solonoid problem?