Need help

There's nothing secret about heating air.

If you are exhausting the heated air, figure that 1 CFM of air flow will rise about 1.8 degrees C per heater watt.

So 10 CFM, heated 50C, needs about 250 watts. There's a reason that a hair dryer may use 1800 watts.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

Insufficient info; under the right conditions, you might need as much as one watt.

Check; under the right conditions, one might need as little as 1 megawatt.

If the stream is steady and really steady-state, just mock up the fan system as exactly as you can in a few hours. Then see what current it takes to get the

140 F. For power applications such as heating, designers typically try to use high voltage since it's easier to work with. If you need 240 watts to do your heating say, that would be 10 amps at 24 volts. (24x10) But if you use 120 volts, then you need only around 2 amps. Think hair dryer. You can mock up a hair dryer type heater with a light dimmer and an actual hair dryer element.

For any kind of precision, you will need a feedback electronics - but hair dryers don't use feedback, and maybe your app doesn't need fine temperature control.

and before the baying dogs of criticism can start their cries, make sure the light dimmer and hair dryer are matched for power. If the low setting on the hair dryer is 500W say, then even a 250 watt dimmer should work at a very low setting. In working with (relatively) high voltage, use only one hand at a time and don't stand in water. Idea is prevent any current from flowing through your heart. In addition, you can use a power strip with a built-in circuit breaker.

Others may have different opinions about high current al low voltage, if they can focus on the problem here.

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A calorie warms or cools the temperature of one gram of water 1C. 

A BTU warms or cools the temperature of one pound of water 1F. 

Or something like that...