Aprilaire Humidifier 700 model shuts itself off repeatedly

[legaleagle]

We had an aprilaire 700 model installed about 4 years ago when we moved into our house.  For the first year or so it worked decently though it was usually about 8-10% below the set level on the dial control (sorry, I didn't see a model number on the control but I can post a picture of it if needed).  This year, after much fussing, replacement of hoses and filters, etc it shuts itself off after about 12 hours.  If I turn the dial to reset and then back, the green light blinks several times and then water flows again.  Of course, every time the furnace guy is out to check it appears to be working perfectly.  What in the world could be wrong with it?  Should we upgrade our thermostat to a model that also controls the humidity (very doable since the thermostat is installed directly above the furnace on the next floor?  Should we just replace the current humidifier control?

TIA!

Sarah

[appl.tech.29501]

If your humidifier is equipped with an Automatic Humidifier Control with

Water Panel change indicator, after replacing the Water Panel, turn the

control knob to the “Test/Reset” position until the “Humidifier On” light blinks

to reset its timer. (Blower must be operating and HVAC calling for heat.) Be

sure to turn the control knob back to it’s original setting. If the “Humidifier On”

light continues to blink, your humidifier is in Test mode. DO NOT LEAVE THE

CONTROL IN TEST MODE OR HUMIDIFIER WILL NOT OPERATE.

[legaleagle]

Yes, I do the reset procedure, set it back to 40%, water starts flowing, fan's blowing and 24 hours later when I check on it, it's shut itself off. Reset, rinse and repeat. It's almost as if something is tripping a safety somewhere but I have no idea why. We always leave the HVAC fan set to "on" on the thermostat.