24vdc fan blower to 12vac transformer

is it possible to connect a 24vdc fan blower to 12vac transformer?

Im making a fan regulaotr pls help

Obviously the fan will run much more slowly. You need:

A rectifier bridge, of the appropriate voltage and current rating. (Voltage rating = transformer AC output voltage times 1.5 (or higher), current rating = fan motor current (or higher.)

You can buy a ready made bridge, or you can build one out of four diodes (of the appropriate voltage and current rating, as above).

The current to the motor will be a pulsed DC, but motors are quite happy with this.

If the motor runs backwards, swap over its leads.

Circuit below.

If the 24 VAC blower is a "brushless" type it will not like pulsed DC. A filter capacitor is needed and the value should be 5000 uF per amp. The DC voltage will be approximately 14 volts.

This is a capacitor input rectifier and that will cause higher RMS current in the transformer windings. To keep the transformer temperature down the current rating should be twice the fan current.

If you want 24 VDC a voltage doubler circuit can be implemented along with a series-pass regulator.

Another thing to consider is that the open-circuit output voltage of a transformer will be higher than the rated voltage (the voltage at the current the transformer was designed for). Since you didn't offer the current rating on the transformer (I'm assuming you already have a 12VAC transformer in mind, else why ask the question). So, if the current rating on the transformer is higher than the current required to run the fan blower, then you'll come closer to the 24 VDC to run the fan.

Bottom line, you can always use more transformer than required. One generally designs for the optimal balance between cost and functionality, but if you already have the part, or if it's on sale, or something, then why not. As long as it delivers the required power and will fit in the box, then yer good to go

Thank you David, I stand corrected.

As Steve indicates below, the transformer must have a current rating at least equal to that of the motor.