24VAC humidistat?

Funnyfarm · #1 03/14/10, 02:09 PM

I just bought a cheap humidistat from ebay with the hopes of connecting it to a small portable humidifier for my incubator. Now that it is here I find that it is 24VAC. Is there any way I can still make this work? The humidifier plugs in to a standard wall outlet.

agmantoo · #2 03/14/10, 02:34 PM

How many amps does the 24 volt ac device draw? Once I know that I will assist on selecting a transformer to power the unit.

Funnyfarm · #3 03/14/10, 03:49 PM

The humidistat is just a switch, on the instructions it says 1/2 amp required

agmantoo · #4 03/14/10, 05:13 PM

I need to know more about the humidifier. Where you expecting to control the humidifier as a separate device with the power to the humidifier being controlled by the humidistat or is the humidstat a replacement one for what was part of the original humidifier? I apologize for not being more articulate with my first reply.

Funnyfarm · #5 03/14/10, 05:30 PM

The humidifier is a small one that I was hoping to control with the humidistat. My plan was to splice the cord on the humidifier and connect it to the humidistat

agmantoo · #6 03/14/10, 06:11 PM

I now need to know the wattage or amp draw of the humidifier. It is a 120 volt ac humidifier isn/t it?

**Ross** · #7 03/14/10, 06:18 PM

You need a transformer that takes 120 down to 24 v. You put the humidistat to a relay that uses 24 v to switch 120 ac assuming the humidifier runs on 120v. (this is where it gets critical to know how many amps your humidifier takes) The relay has to be able to handle the required amps or you'll fry it. Then your spliced cord from the humidifier goes to the 120 side of the relay and neutral. Be sure to ground the thing even if it never had one.

Funnyfarm · #8 03/14/10, 06:41 PM

How much should I expect to pay for the transformer?

Funnyfarm · #9 03/14/10, 06:43 PM

Humidifier is 120V, 60HZ, .45 amps

agmantoo · #10 03/14/10, 07:22 PM

As Ross stated.
You need a 24 volt AC door bell transformer or equivalent transformer rated at 1/2 amp or higher and a small relay with a 24 volt AC coil rated less than 1/2 amp or less. The relay points need to be rated at approximately 5 amps at 120 volts AC. Ebay has some transformers and relays.
From your 120 Volt house supply, connect the door bell transformer primary side to the 120 volt AC. Then connect the secondary with one wire to the humidistat switch and the other wire to one side of the relay coil. From the humidistat switch run a second wire to the relay coil so that when the humidistat trips to turn on the coil is activated. Each time the humidistat trips on the relay points will close.

Wire the humidifier into the relay just as you earlier described as to how you had planned to do the humidistat.

Now with the system setup in this manner when the humidistat activates, the coil on the relay will connect the points closed on the relay. The relay points can easily carry the amperage and will turn the humidifier on. When the humidistat turns off the coil voltage to the relay will cease and the relay points will open and the humidifier will turn off. This arrangement should give long service as it can handle the amperage for both the start and run conditions of the humidifier.

Funnyfarm · #11 03/15/10, 12:23 AM

Thank you Agmantoo and Ross, That was exactly the information I needed.