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Wired my Aprilaire model 60; Furnance Always On?!?

Hi.. i wired my new Aprilaire humidifier exactly as directed to an older Lennox furnace. The furnace now turns on, no matter what the thermostat setting.

It has something to do with the "C" connection: if I remove the "C" wire from the Aprilaire control (which is connected to "C" on furnace), no problem. As soon as i connect the "C" wire back, furnace turns on--even if thermostat is set to "system off".

I double-checked it all. Humidifier runs as per Test cycle. I installed Aprilaire humidifiers in the past no problem. What is going on?!???

Thank you, Dan

Reply to
Martinic
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There's no way it's wrong. I swear i have checked it all over and over; the wiring diagram from the box is so clear and simple:

Between Model 60 controller and Furnace:

R goes to R C goes to C W goes to W Gf goes to G on furnace

G from thermostat goes to G on humidistat

OMG it's exactly like that.

10 years ago i installed 5 Model 500s for friends, a Fanhandler, and an air exchange. You guys helped me out. They all still work perfect.

I am not a first timer.

I am going nuts tonight. Please help.

:Dan

Reply to
Martinic

your installer is an idiot.

Reply to
Steve

I am the installer. I am not an idiot--i swear it. But i am missing something, obviously don't have the experience for this situation, and need someone to point out what's obvious.

The Lennox furnace is really old, and the terminal strip is located outside the unit sticking out of a box labelled Honeywell. It buzzes, but the buzz goes away after i connect the "C" from the humidistat.

Everything was working fine before i connected the new humidifier control (as per directions). It's not my house btw.

Thank you, Dan

Reply to
Martinic

OK, then it must be working perfectly :-)

That time ten years ago - did you pay your minion dues ? I don't recall getting your check.

Reply to
.p.jm.

Steve.. i meant that i am the one installing the humidifier. Are you saying that the original furnace is installed incorrectly? I have this feeling that there's a problem with the ground or whatever the "C" is for.

Dan

Reply to
Martinic

It's wired correctly; there must be something wrong with:

a. older furnace needing different directions with new humidifier control? b. something wrong with the old furnace's control / wiring (the terminal strip / box buzzes)? c. incorrectly wired from the begining?

No--i didn't pay the dues. But i thanked profusely :)

:Dan

Reply to
Martinic

Hi, Are you sure it is model 60? Mot 600? I notice your email add. shows you are in Canada. I am in Calgary. G is furnace fan control lead, C is 24V AC control voltage common lead, W is heat control lead, R is 24V AC control vltage lead. Remember humidifier comes on only when furnace comes on and fan is running. Wonder if you left out humidistat? What is your thermostat?

Reply to
Tony Hwang

I'm pretty sure he understood that ;-)

No, he said you're an idiot :-)

Reply to
.p.jm.

On some systems I've seen control voltage back-feed through the thermostat "G" connection and cause weird problems. If the system works fine without the new gadget, you my have to pick up a relay from your local supply house to isolate the control circuits from each other. I would check to see if "C" is the chassis ground like on many systems. Hook your DMM between the furnace cabinet and the humidifier chassis to see if you get a voltage reading when it's misbehaving. Google "Aprilaire Isolation Relay for General Purpose Use" You will find a lot of information.

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TDD

Reply to
The Daring Dufas

Thanks guys.. i am done with it tonight. Going to continue research tomorrow and will follow your lead TDD. Argh. I hate it when things don't work like they're supposed to.... Good Night.

Dan

Reply to
Martinic

It appears that the idiot installer has wired the controls incorrectly.

If the furnace board doesn't have a "HUM" terminal, then it probably falls into the "Jurassic" catagory and needs to be updated/upgraded and or replaced anyway.

Either way, it helps a lot to *READ* the installation instructions for the furnace, dehumidifier, and controls with specific attention to the control wiring and setup.

Reply to
Steve

Sorry: it's the Model 500 with the new Model #60 humidistat controller.

Dan

Reply to
Martinic

If I disconnect the humidistat, the furnace works fine. If i wire up all the connections for the humidistat except for the "C", the furnace works fine (but humidistat not yet).

As soon as i even touch the "C" wire from the humidistat to the "C" terminal on the furnace, the furnace starts up right away. Obviously, it's not supposed to.

The humidifier then works fine though.

Why is the furnace turning on as soon as the "C" is connected between the humidistat and the furnace?????

Dan

Reply to
Martinic

Are you talking about the Aprilaire Model 50 current-sensing relay? I suppose i could buy that and install it, but the humidistat that comes with the humidifier already has a function to humidify even if no heat and besides, it's *supposed* to work! This is a very simple hook-up; i think it has to be a simple problem too.

I want it to work like it's supposed to!! :)

:Dan

Reply to
Martinic

Hi.. not sure what you mean by "hook up DMM between furnace cabinet and humidifier chassis"--do you mean to actually touch the DMM leads to the cabinet sheet metal of the furnace? The humidifier is plastic-- what would i touch the lead to?

Thank you, Dan

Reply to
Martinic

If I disconnect the humidistat, the furnace works fine. If i wire up all the connections for the humidistat except for the "C", the furnace works fine (but humidistat not yet).

As soon as i even touch the "C" wire from the humidistat to the "C" terminal on the furnace, the furnace starts up right away. Obviously, it's not supposed to.

The humidifier then works fine though.

Why is the furnace turning on as soon as the "C" is connected between the humidistat and the furnace?????

Dan

Something is *NOT* wired right.... It could be *in* the furnace, it could be

*in* the humidifier(factory mis-wired) it could be something is hosed up in either/and/or the thermostat or humidfier control. there could be a short inside of the control wires too..... If you have a digital thermostat, it could be that its not configured correctly. The list goes on and on....
Reply to
Steve

I meant any metal chassis, There could be a metal chassis inside the plastic case, if not, don't worry about it. :-)

TDD

Reply to
The Daring Dufas

Is it correct to assume that since everything worked fine before i installed the humidifier, then the furnace and thermostat are free of error?

I've been doing some more research: W deals with the signal to heat, is that right? Therefore, can i assume that for some reason the humidistat is energizing W when it's not supposed to be? This model #60 humidistat has the ability to control the blower but it's not supposed to call for heat.

I can measure W across C to see if there's voltage when i hook up C to humidistat, right?

Thank you, Dan

Reply to
Martinic

Is it common to find a mis-wired brand-new from the box digital humidistat? It looks like a printed circuit board--not loose wire soldered by people?

Dan

Reply to
Martinic

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