Fan motor help

[Roundgunner]

I hooked this Modine up so the return goes thru it before going back out to the boiler. The fan is just hooked up to plug in when I want to get heat in the garage/shop. The water is about 155. It is not really throwing as much heat as I remember from years ago in the basement.

Question is: can I put a rheostat on this kind of motor without doing any harm to it? I feel like the fan is blowing so hard it is not transferring heat, is that possible?

 

[Fred61]

A variac will work to slow the rotation although that isn't the way variable speed motors are usually controlled .

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[Roundgunner]

A variac will work to slow the rotation although that isn't the way variable speed motors are usually controlled .

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What would be the normal way?

Do you think a slower fan speed could help with heat exchange?

 

[Fred61]

A normal variable speed motor is built specifically for variable speed with electronics that are compatible with a matching control box with a bunch of complicated electronics that allows it to vary it's speed while having little effect on torque.

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[Fred61]

Lower speed will make it more comfortable in the space.

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[Roundgunner]

Thanks for the info, It seems like I'm not getting enough warm air. I have the controller and thermostat from the basement but I thought it controlled the pump, when the pump sent hot water the controller sensed the hot water and turned the fan on.

If that is what it is supposed to do it wont work for me now because the water going thru it is always hot.

 

[Fred61]

The thermostat controls the circulator and an aquastat attached to the pipe will turn on the fan when it senses the temperature of the pipe. The aquastat is adjustable.

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[mustash29]

Since the water temp is only 155 instead of 180-ish, the heat output of the Modine is going to be less than it was before. With the fan running it will feel like a cool wind chill instead of a blast of heat. Slowing the fan speed will reduce the wind chill effect, but you will still be getting the same amount of BTU's out of it, just less than before.

Don't use a "rheostat" or dimmer knob. These basically just reduce the voltage and will make the motor hum and buzz and possibly shorten it's life. You need a (variable) electronic speed control. It will turn itself on & off rapidly, basically "chopping" the 60 hz a/c to a lower frequency. 50% would be 30 hz, half speed & about half the airflow.