What is the 3300-386 transformers function and how do you trouble it ?

Call an electricist. You might have some serious problem in the transformer. That ·humming" sound might be the transformer burning out!

The hum could just be the control transformer, but that's usually a very light and barely perceptible hum. If its a louder hum, and it stops after a few minutes, the hum could be the blower motor refusing to start for any number of reasons, then cycling on its internal winding thermostat.

I'd call a service tech.

the hum is probably coming from a relay. there is nothing in a transformer to hum.

Hello, yes the transformer will get a 120 volts from the Furnaces control board, there should be a terminal labeled HUM on the control board. You need to bring 2 wires one from HUM and one from a nuetral tap on the board to the line side of the transformer, this way every time the blower motor on the Furnace turns on the humidifier will aswell.

Yes you still need a transformer the hum. port on the furnace goes to the 24 volt transformer. one leg of the primary side goes to the transformer and the other leg of the primary goes to the neutral on the board. Then you have your 24 volt terminals one goes directly to the humidifier and the other goes to the humidistat the other wire from the humidifier goes to the humidistat.

Okay, I looked up the installation manual online to see exactly what you are working with.
Yes the R anc C need to be hooked to the transformer supplied with the unit. The primary 120v side needs to be hooked into the power coming into the furnace. this can easily be done were the L and N get hooked into your furnace or circuit board on the furnace. This will provide the contiuous power to the unit. Preferably you will hook this after the door switch of the furnace so that you will kill the power toit if you take the blower door off.
The ODT terminals are for the outdoor sensor if you want to hook that up it will vary the humidiy in your home according to the outdoor temperature then.
Now the W/G and Cf terminals. If you have 24v coming from the HUM terminals of your furnace you DO NOT need a second transformer. You must check your furnace manual or check the voltage to them with the furnace blower energized. The HUM terminals will only have power to them when the blower should be running.
If the HUM terminals are 120v then you need to get another transformer and hook up the primary side to the HUM terminals so it is powered only when the the blower is running. Hook the secondary side to the W/G and Cf terminals.
So bottom line is that you need to figure out what voltage your furnace is giving to the HUM terminals and then go from there. Some times the EAC terminals or the ACC terminals will be 24v on the furnace board. Either of them could be used also, as they are only energized when the blower is running also.

Heatman101

some one has the humidifier hooked up to the R and W on the furnace.
1. it should be hooked up to its own transformer or to a proper low voltage terminal on the circuit board(beware there are high voltage HUM terminals) markd HUM and the other wire to C or the common.
2. You could hook the wire to W or white and C Common but I would rather see a seperate transformer since there is a possiblity this could cause solenoid chattering

It's not difficult if you have good access to the transformer. I would try something a little "harder" than foam -- like a piece of rubber (old inner tube?) under the transformer mount and screw the transformer down very tightly.

a very subtle hum or buzz is normal and is the transformer that creates 24 volt control voltage continually. some are noisier than others . sometimes a tap or bending of the transformer will tweak the metal enough to make it quieter. they can also get loud if incoming voltage is not correct. incoming 120 volts on a furnace is not usually a problem but the transformers are usually wired to the available incoming 230 voltage or 208 voltage if it is a heat pump or electric heat. If it is powered by 230 or 208 volts as most heat pumps are ,then you need to verify which you have and connect the appropriate leads from the trans former to power . it tells you on the side of the transformer which to connect to 230 and which to connect to 208. tape or cap off any unused leads.since you have not mentioned any performance problems i assume the fan does come on when called for and that it is not the loud hum you hear. switching the fan switch at stat to on should bring the fan on right away. if it doesn't then you may hear a loud hum and then youll need to check the fan motor and capacitor. but it sounds like a noisey transformer from here.

I WOULD CHECK TO SEE IF YOU HAVE ENOUGH V/A OUT-PUT ON TRANSFORMER. I DONT KNOW IF YOURS CAME WITH ITS OWN TRANSFORMER. IF IT DIDNT YOU SHOULD HAVE A MINIMUM OF A 40 V/A RATING STAMPED OR PRINTED ON THE EXISTING TRANSFORMER. IF THE TRANSFORMER IS EXTREAMLY HOT ... YOU MAY NEED A 75 V/A TRANSFORMER WITH THE SAME VOLTAGES. INCREASING THE V/A CANNOT DAMMAGE ANYTHING IT JUST GIVES YOU MORE POWER WHEN EXCESIVE CONTROLS AND WIRING ARE ADDED TO A HVAC LOW-VOLAGE (24v) CIRCUIT. IF YOU LIKE YOU CAN CALL ME AT 727-363-7071. I AM A RETIRED HVAC&R CONTRACTOR WITH 45 YEARS EXPERIENCE. I HATE THE NEW SENSORS THEY HAVE TO ACTIVATE THESE NEW HUMIDIFIERS. I USE TO WIRE THE HUMIDIFIER TRANSFORMER (SUPPLIED WITH HUMIDIFIER) TO THE LINE (110V) SIDE TO THE LOW SPEED ON YOUR BLOWER MOTOR. THAT WAY THE ONLY THING THAT INTERUPTS THE CICUIT IS THE HUMIDISTAT. YOU NEVER WANT THE HUMIDIFIER TO RUN IF YOUR SYSTEM IS NOT "CALLING FOR HEAT". NEVER TRY TO ENERGIZE THE WATER SOLENOID THROUGH YOUR HEAT WIRE(USUALLY SMALL THE WHITE WIRE) FROM THE THERMOSTAT. THIS WILL RESULT IN BURNING YOUR HEAT ANTICIPATOR OUT ON THE T-STAT.