I have Honeywell Humidifier HE225A, Honeywell Thermostat TH6110D and Honeywell Humidistat H8908B all installed already. Now my Humidifier runs 24/7 wasting water because it is connected with the furnace blower fan cycle which is on 24/7. How can I wire it so that it only runs during the heat cycle.
How to wire the Humistat and Humidifier so that Humudifier runs only during heat cycle
humidifierhvac
Related Solutions
You could use the EAC-1 terminal to power a step-down transformer. This is common with furnaces that energize the HUM terminal to line voltage.
Check the humidifier manufacturer, they should have a properly sized transformer to fit this exact need. They should also have a wiring diagram for this type of setup, in the installation instructions.
Basically, the primary side of the transformer will connect to the EAC-1 terminal, and a neutral terminal on the furnace control board. Then the secondary side will power the humidifier.
Whenever EAC-1 is energized, it will power the transformer, and the humidifier will turn on.
As noted in the comments on the question, you may not get the expected results.
The terminal circled in red should be labeled HUM-H, which is the humidifier (hot) terminal. This terminal is energized to 120 V when the system is running in heating mode.
The terminal circled in blue is EAC-N, which is the electronic air cleaner neutral. This terminal should be tied to the other neutral terminals, as well as the system neutral.
If you move the humidifier transformer wire from HUM-H to EAC-H, the humidifier will run whenever the fan is on. However, this also includes when the system is in cooling mode, which is not recommend.
What you could do, is install an override switch, which will allow you to manually turn off the humidifier during the cooling season. So you'd run a wire from the EAC-H terminal, to one side of the switch. Then connect the humidifier transformer wire, to the other side of the switch. This way when the switch is closed, the humidifier will run with the fan. But when the switch is open, the humidifier will not run.
If you don't want a manual switch, you could mess around with a relay or other control circuitry.
Using a relay, it could be wire up like this.
That way the humidifier will run whenever the fan is running, except when the thermostat is calling for cool.
Best Answer
There should be a terminal on the board of the furnace supplying either 24v or 120v. Usually marked hum. That's where you pick up power for the humidifier.
For like 20 years I've been wiring the humidifier from W to C without a single issue. On a call for heat W is energized if the humidistat is calling the humidifier energizes and compleats to common.