How do I hook up my humidifier to my furnace so it only runs when furnace heats my house. Just want to make sure it does not turn on when A/C in summer goes on. The person who installed my furnace did not hook it up and is not answering my calls. Thanks
How to electrically hook up the humidifier to the furnace and have it run when furnace is running and not A/C in summer
furnacehumidifierhvac
Related Solutions
Where to find the specifications
Listed on the furnace
Somewhere inside the service panel of the furnace, there should be a schematic for the furnace. This may list the electrical specifications of the blower motor. If not, the blower motor itself will have a label on it. It should list the voltage, amperage, horsepower, etc.
Using an Ammeter
An ammeter is used to measure the amount of current flowing through an electrical circuit. You can use a clamp on ammeter to measure the amount of current being used by the blower motor while it's running.
Simply set the meter to measure current (A in the pictured meter), and clamp it on the hot wire feeding the motor.
This method may require working on or near live wires, please use caution and/or consult an expert to take the readings
Calculate Usage
With the above information and Ohm's law, it's easy to determine how much power the motor will use over a given time period.
Ohm's law says that Power (P) = Voltage (V) x Current (I), so we can determine how much power the motor uses at a single instant in time.
ex.
P = 115V * 5.2A
P = 598 Watts
Next we have to determine how many kilowatt hours the motor will use, which we do by dividing by 1000.
P = 598 W / 1000
P = 0.598 kWh
So for every hour the motor runs, it will use 0.943 kilowatts of power.
Total power/day = 0.598kWh * 24h
Total power/day = 14.352kWh
Total power/month = 14.352Kwh * 30
Total power/month = 430.56kWh
Finally, if you multiply this number by the amount you pay per kilowatt hour. You'll see just about how much it costs to run the motor constantly.
Cost = 430.56kWh * $0.07
Cost = $30.14 per month
Notes:
Results using this process will be an estimate only.
Values used are not actual values, they are example values only.
Calculations may be incorrect, nobody checked my math.
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
On most newer furnaces, on the control board there are specific terminals for a humidifier. The engineers have built into this control board the exact criteria that you are looking for.