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codym 12-29-2012 06:48 PM

Aprilaire 700 wiring to Bryant Evolution 98MA
I installed an Aprilaire 700 fan power humidifer to a Bryant 98MA furnace. However, nothing on the humidifier seems to work. I have installed the humidifer in the evolution thermostat and it thinks the humidifier is on and running.

Here is how I wired it up:

I connected the HUM and 24volt Common from the Bryant furnace board to 1 and 3 of a white rodgers 90-380 (relay). There is 24v present on the relay at 1&3 but nothing on 2&4 and 5&6.

I then connected 2 and 4 to the aprilaire brown wires on the humidifier.

Is this wired up correctly?

carmon 12-29-2012 11:01 PM

no it is not wired correctly..... where is the water solenoid getting its voltage.... and why are you using a relay.....:eek:

codym 12-30-2012 09:06 AM

Yeah I realized the solanoid wasn't powered last night, and connected the wires to the solanoid yellow wires.

The reason I'm using a relay is that the Bryant furnace installation manual says that "most fan powered humidifiers prodcue internal 24VAC in order to energize upon a switch or contact closure. For this application a 24VAC N.O. Isolaton Relay (DPST) must be used..."

based on this the HVAC supply company gave me the relay which is really confusing me.

carmon 12-30-2012 09:16 AM

that makes sense..... post a picture of wiring diagram.... if the humidifier is producing 24 volts you would need the relay.... never installed one like that sorry if I caused more confusion....:eek:

beenthere 12-30-2012 09:37 AM

Look at the wiring instructions that come with the humidifier.

codym 12-30-2012 09:59 AM

Here is the wiring diagram for the humidifier. However, I am not using the aprilaire controller I am using the furnace and Bryant thermostat to control the humidifier.

The installation paperwork under furnished items says it includes a 24VAC transformer, however I can't for the life of me find one or locate it in the parts list on in the humidifier. I'm wondering if it isn't part of the digitial control unit I'm not using.

In my mind I should be able to just wire the HUM and 24VAC common to the brown wires coming out of the humidifier. When energized they should kick on the fan and solenoid.

However due to the possibility of the 24VAC transformer backfeeding into the furnace I don't dare go directly to the furnace 24VAC.

chitownken 12-30-2012 10:22 AM

Did you check the voltage coming from the HUM terminal? On many furnaces that is 120, not 24.

beenthere 12-30-2012 01:59 PM

The wiring diagram that came with the humidifier shows it needs a transformer to power the solenoid.

The furnace HUM terminal is usually 120 volts. And is used to power the transformer that you install for the humidifier.

chitownken 12-30-2012 03:13 PM

The caution label on the wires from the humidifier specify to NOT connect it to line voltage and the HUM connector is 120 VAC. The transformer supplied with the Aprilaire 700A (digital control) or the 700M (manual control) looks like the ones that normally come with doorbells. Mounts in a conduit knockout, has 2 wires that come out of the mounting (black and white 120 VAC supply) and has 2 screw terminals on top. You need to know what type of contacts the humidistat portion of your thermostat provides. Are there 2 terminals that get connected together when the control calls for humidification (dry contacts) or is there only 1 terminal that supplies 24VAC from the R terminal when humidification is needed.
Post the answers back and we can tell you how to wire it up. You might need to trade that relay for a 90-362 instead of the 90-380.

codym 12-30-2012 05:16 PM

I have the relay and it looks exactly as you described. Black and White wires with two screws on the top.

Based on the Bryant Contoroller and Furnace manuals it appears that there are only connections from the 24VAC common and the HUM when connecting a humidifier. It does state to NOT use the humidifier controller but let the Bryant system run the humidifer.

beenthere 12-30-2012 05:23 PM

Use a multimeter and read the voltage from the Hum terminal to ground while the heat is running.

chitownken 12-30-2012 07:43 PM

The Aprilaire 700 needs 2 electrical connections. It needs 120 volts for the fan supplied via the plug in power cord. That only runs the fan and does not supply anything else. It also needs 24VAC supplied to the 2 brown leads that come out in the lower right, near the solenoid valve. When supplied with 24 VAC to those connections, the valve will open and the internal relay will energize the fan.

Is the humidistat part of the controller? Like the Honeywell IAQ system? If that is the case, you should be able to just connect the 2 brown humidistat wires directly to the controller without the need for the relay. If you want to isolate the humidifier completely from the furnamce controller, you would need to connect that 24VAc transformer supplied with the humidifier to a power source, then use it and connections between 2 and 4 on the relay to run the humidifier. Connect humidifier lead 1 to one side of the transformer. Connect the other side of the transformer to relay terminal 2, connect relay terminal 4 to the other humidifier lead.

codym 12-31-2012 09:19 AM

The Bryant Evolution Controller has a humidistat built into it and talks to the Bryant Evolution furnace control board via two data lines. So according to everything I seen so far Bryant only has you connect a humidifier to two locations on the furnace board. 24VAC common on the accessory strip and the HUM. Which I need to very if it is 24VAC or 110 VAC.

I'm out of town for New Years but I'll check the HUM terminal when I get home.

codym 12-31-2012 09:47 AM

Ok, we are leaving later than I was told. :)

So I went down and check the voltages. With the heat running and a humidifier installed in the thermostat controller, the HUM terminal is reading 24VAC and the 24VAC Common terminal on the accessory row is not reading anything.

codym 12-31-2012 09:58 AM

Just got off of the phone with Aprilaire and was that the aprilaire 700 with the grey color, which is what I have works exactly as chitownken described.

So I can wire directly from the HUM and 24V common to the brown wires.

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