Rented the Circle a couple of weeks ago. Of course that very night I was wakened by a noise coming from the furnace room during the middle of the night. Couldn’t find the cause. Sounded like somebody banging the pipes. Why is it something like this always happens after you’ve seen a scary movie?
Finally tracked down the source of the noise to the humidifier. The solenoid that controls the flow of water to the humidifier was switching off and on and the pipes next to the air ducts were echoing the noise throughout the house. Now why would this solenoid be rapidly switching on and off? When the humidistat is turned lower the problem stops. Any solutions?
Replies
Does the humidistat have an external temperature compensator? (Is there a 2-wire cable leading from the humidistat to the outside? This allows the humidistat to anticipate external-and hense internal-moisture levels.)
Is the humidistat mounted in a return duct? (So it senses house humidity, not treated outflow in the supply line to the house registers.)
If you have a bypass model humidifier (a slipstream is taken from the outlet plenum and directed through a moisture pad back to the return duct), is the humidistat located upstream of the humidifier return connection (i.e., the return air should enter the return plenum, be sensed by the humidistat, then see the humidified slipstream. You don't want the humidistat to sense the just-treated air.)
Have you ever noticed this cycling before (in years past.) It's that time of year when the heating units are not turning on as often, and the humidity levels are rising.
I'd try it again and see if it continues. The humidistat shouldn't rapidly cycle as you've experianced. If the system is installed correctly, the solenoid should open and close within a predetermined range set by the humidistat. Adjusting the setpoint on the humidistat changes the desired humidity levels in your house. The solenoid is just responding to the signal from the humidistat. If the humidistat can't make up it's mind, it may be time for a new one.
All signs (to me) point to the humidistat. Another possibility (however far-fetched) could be the solenoid chattering due to high water pressure. (Since it stopped cycling when you adjusted the humidistat, that makes this extremely unlikely.) After I jacked my pressure up to about 85psi, the solenoid would chatter, send a resonance throughout the ductwork. To alleviate the noise, I sweated in a manual valve to the solenoid and throttled it down, eliminating the noise-but left it open enough for adequate flow.
"Does the humidistat have an external temperature compensator?"
No
"Is the humidistat mounted in a return duct?" Yes
"If you have a bypass model humidifier (a slipstream is taken from the outlet plenum and directed through a moisture pad back to the return duct), is the humidistat located upstream of the humidifier return connection " No located downstream.
"Have you ever noticed this cycling before (in years past.)" NO
"If the humidistat can't make up it's mind, it may be time for a new one."
The humidistat is about a year old.
"All signs (to me) point to the humidistat. Another possibility (however far-fetched) could be the solenoid chattering due to high water pressure."
I'll adjust the valve and try a lower pressure....thanks.
If I read you correctly, you said the humidistat is mounted in the return duct AFTER the outlet of the humidifier, is that right?
If so, then you should move the humidistat so it is before the return from the humidifier. At its present location, the humidistat is not sensing just the house humidity levels, but rather that of the house combined with the moist air after the humidifier. Installation instructions for the bypass type humidifiers state firmly (in bold) that the humidistat must be located upstream of the humidistat connection. The humidistat is trying to regulate your humidity based on a much higher level of moisture than what's in your house. If things have seemed dryer than they should be, it may be because the humidistat thinks there is more moisture in your house than there actually is, and doesn't open the solenoid when required.
It's possible that this could be causing the problem, but it sounded as though your solenoid was cycling too fast; there's a time issue here of instrument response and setpoint allowances, and it sounds like the cycling is too fast for actual system characteristics to have caused the problem.
Whether or not throttling the flow to the solenoid cures what ails you, you should move the humidistat to accurately control your house humidity.
I have the installation instructions for an Aprilaire bypass type humidifier if you need it.
Good luck.
I never met a tool I didn't like!
If I read you correctly, you said the humidistat is mounted in the return duct AFTER the outlet of the humidifier, is that right?
My mistake the humidistat is mounted before the outlet. It is a pretty old installation 30+ years - I don't think that is the problem.
"but it sounded as though your solenoid was cycling too fast; "
I am sure that is the problem. But why?
"Whether or not throttling the flow to the solenoid cures what ails you, you should move the humidistat to accurately control your house humidity."
I am playing with the water flow hopes that solves the problem.
"Good luck."
Thanks again.