Kenmore 3000 Humidifier on Bryant 395CAV furnace


Old 02-04-14, 12:41 PM
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Kenmore 3000 Humidifier on Bryant 395CAV furnace

A few years ago I was able to get a great deal on a Kenmore 3000 central humidifier. I've finally gotten to installing it. I've got the humidifier mounted on the supply plenum, wired to the humidistat (included with the unit) which is mounted on the return plenum, and water supply hookup is in progress. The humidifier is 120VAC and the hot passes through the humidistat which is a 120VAC unit.

If I wire the humidistat directly to AC, the humidifier will run all the time the humidistat calls for humidity. This seems like a bad idea as it will get the duct interiors wet when the furnace is not running. I want to wire it to run only when the furnace is heating.

I got a manual for the Bryant 395CAV furnace and it says there is a HUM terminal on the board (I have not found it yet) but it is a 24V terminal which is energized "after the pressure switch closes". There are also 120V leads for and electronic air cleaner which are energized "during blower motor operation).

I figure I have two options - 1) get an isolation relay, with the coil connected to HUM and COM and the contacts connecting to hot in and hot to the humidistat. 2) connect the hot and neutral to the EAC terminals. (I'm leaing to 1 as the proper and safe way.) (A third option is a sail switch, but I don't see the point with the HUM terminal supposedly being present.)

So, the questions
1) What is the best way to power the humidifier only when the furnace is heating.
2) If the isolation relay, where should it be mounted. In the furnace or in a separate enclosure of some type?
3) Should I tap the power for the dehumidifier from the incoming leads inside the furnace, or from a junction box outside the furnace? (if the relay is mounted in the furnace, it would make sense to tap into the incoming furnace leads)
4) I am looking at the following unit. It does not give voltage, or AC vs DC ratings for the contacts. Is this appropriate to use for this application?
Buy SPDT Isolation Relay | Jackson Systems RY-1-HB

I have not as yet found a amperage rating on the humidifier.

Help is greatly appreciated!

Below is the text from the Bryant 395CAV furnace manual regarding accessories.

1. Electronic Air Cleaner (EAC)

Two quick-connect terminals marked EAC-1 and EAC-2 are provided for EAC connection. (See Fig. 10.) These terminals are energized with 115-v, (1.5-amp maximum) during blower motor operation.

2. Humidifier (HUM)

A quick-connect terminal (HUM) and screw terminal (COM) are provided for 24-v humidifier connection. (See Fig. 11.) HUM terminal is energized with 24-v (0.5-amp maximum)
after pressure switch closes.

WARNING: DO NOT connect furnace control HUM terminal to HUM (humidifier) terminal on Thermidistat ™, Zone Controller or similar device. See Thermidistat, Zone Controller, thermostat, or controller manufacturer’s instructions for proper connection. A failure to
follow this warning could result in fire.

NOTE: A field-supplied, 115-v controlled relay connected to
EAC terminals may be added if humidifier operation is desired
during blower operation.
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Old 02-04-14, 05:23 PM
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Welcome to the forums.

I'd use a basic 24vac SPST NO relay like the 6AZUZ2. Connect it to the C and HUM terminals.
The relay can go inside the furnace.

Industrial Grade 6AZU2 Enclosed Fan Relay, SPNO, 24V: Amazon
Old 01-29-16, 11:03 PM
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Probably not what you were looking for, but I have the same humidifier and I decided to wire in a sail switch. The humidifier is powered whenever the blower runs.
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