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nolandbob · Feb 8, 2009, 04:40 PM

I have a Carrier 58 SX furnace (22 years old) and had a Carrier Bypass Humidifier installed several years ago (HUMCCLBP 18-A). The humidifer water is now running all the time and does not shut off when the furnace does. The humidistat is wired to R and C at the furnace which I assume or 24 V connections. The panel reading left to right at the furnace has Y W H R GH C and G terminals. Any help you can provide would be greatly appreciaed.

Thanks,
Bob

KC13 · Feb 8, 2009, 04:43 PM

It should be wired to "H" and "C" at the circuit board. This assures the humidifier circuit is only powered during heating cycles. How did it end up connected to "R" and "C"?

nolandbob · Feb 8, 2009, 04:56 PM

Thanks for the very quick answer. It has always been wired this way and it worked for a few years. I assume the humidistat is controlling the water solenoid some how? The humidistat does work when I manually turn it up or down although the water does not shut off until I turn in below the humidity threshold.

Thanks,
Bob

KC13 · Feb 8, 2009, 05:01 PM

There must be another control somewhere, perhaps an airflow switch or current-sensing relay. Otherwise, the humidifier would run water anytime the humidistat was set above the indoor humidity, with or without the system running. Using the "H" terminal will assure it only runs during a heating cycle.;)

nolandbob · Feb 8, 2009, 05:06 PM

Thanks I will give it a try after checking the H & C are a 24 V supply. I am not aware of any other sensors unless it is in the humidistat itself but who knows? It is a Carrier humidistat also and the entire unit was installed by the dealer so I am wondering why the would hook it up to R & C versus H & C? Again, thanks for your help!
Bob

KC13 · Feb 8, 2009, 05:09 PM

You're most welcome. You will find that the "H" terminal is only powered when the gas control is, or in some cases only when the blower is. The "H" designation is for humidifier.

nolandbob · Feb 8, 2009, 05:21 PM

Now that I think of it, I do not believe it has run correct since the last time it was serviced. I wonder if the tech had to remove those wires for some reason and put them back in the wrong locations?

KC13 · Feb 8, 2009, 05:23 PM

Could be. While an error on his part (if so), at least it suggests he was actually doing something beyond a "dog 'n' pony show".:rolleyes: