Humidifiers and Dehumidifiers - Aprilaire 700 humidistat wiring

This is how I have the humidistat wired(please tell me if this is wrong).
24v from furnace accy terminals, 1-24v common(to c on humidistat), 1-24v HUM(to r on humidistat). Then 2 wires going from H terminals on humidistat to brown solenoid wires. Outdoor sensor wired to the ODT terminals.
The unit seems to work fine, and is regulating humidity per the outdoor temperature changes.
However, when the gas comes on and energizes the HUM terminal, both the Aprilaire fan and solenoid starts to run, but stops after 1-2 seconds. This happens 3-4 times(cycles on and off) until it finally starts and stays on once the furnace blower comes on. The unit then runs constant until the t-stat signals to turn off the gas which in turn turns off the Aprilaire.

Does this sound right? Also, how do you tell what model humidistat you have? Does it say so somewhere on the unit.

Jay, I know you said that the "New" model humidistat has an internal 24v power supply. I guess I'm confused as the Aprilaire directions were not that descriptive.

Anyone,.....please Help!
Thanks

Sounds like it's hoooked up right. I went and took a peek of the manuals on line...

Now on your furnace.. Do you know for a fact if the HUM termal is 24 volts? or 120?

Thanks for replying Jay. Yes I do know that the HUM terminal is 24volts, as well as the 24v common,...I tested it with a multimeter. It is energized when the gas is turned on.

Do you have any ideas as to why the Aprilaire cycles on and off until the furnace blower comes on? Is that normal operation?

Thanks for the help.

I am not sure why that is doing that..

The hum only should come on when the bower itself comes on.

You take a reading to see if the 24volt of the HUM termail is coming on and off itself?

Yes I did take a reading to see if the 24v comes on and off. Using the HUM terminal & 24 volt common it is energized with 24-25volts when the gas starts, and drops back to zero when the gas is turned off.

I did not take a reading with just the HUM terminal alone. Is that what you are asking about? Would I use a ground to test the HUM itself?

Thanks

Yes, take a reading alone on the HUM term alone to c/ground. I know on most furnaces, that only get power when the blower kicks in.. not when the gas valves comes on.

Yes Jay you are correct.
I tested the HUM terminal alone to a ground, 24 volts and it comes on when the "first" blower comes on. The sequence is as follows: the first blower(gas combustion blower?), then the gas is lit, then furnace blower(or fan).

The Aprilaire comes on after the first blower, cycles on and off a few times(2-3), until the furnace fan comes on which then the Aprilaire starts, and stays running for the full heat cycle.

I have also checked the voltage during the whole cycle from first blower to furnace fan off and there is a constant voltage of about 24.4.

Any ideas?

Sounds like you may have a defect on the board. Like I said before. Pretty much all of them only comes on when the main blower comes on.

so.. Either live with it and save some $$.. Replace the board, or use the A50 relay.

In the humidistat see if the toggle switch is on power.