Quote:
Originally Posted by gtojohn
825 blower motor? Is that a 230v condenser fan motor I see? So you added 230v to your blower?
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Couldn't find a 825RPM 120v motor anywhere, had to get a 230v. I thought I'd try @ 120v before running 240v to the furnace. The 230v motor runs fine on 120v, needed a 10uf cap to get proper power factor/phase balance. 1.2A draw, rated at 1.8A, didn't see a need to run 240v. It has been running like that all summer, motor stays nice and cool.
Note that the new motor and old motor are both 1/3HP. At 825RPM there is a MUCH lower HP requirement, therefore the motor doesn't over amp. 230v motors will run on 120v, you just have to cut the HP rating in 1/2 and adjust the cap size to ensure the phases stay balanced. Watch amp draw and be sure it doesn't exceed nameplate rating.
You must DOUBLE the cap when you cut the voltage and load in 1/2. Motor amps will stay the same. Motor is rated for a 7.5uf cap @ 1.8A. Should use a 15UF? No, because the actual load is closer to 1/9HP than 1/6HP. I'm at 1.2A instead of 1.8A, so I'm using a 10uf instead of a 15uf cap. I experimented with 7.5/10/12.5 and found 10 to give the best results. Keep in mind that the the motors rated cap is only correct at the motors rated voltage/amps/load. As voltage and load varies so does the "ideal cap".
At the end of the day a motor is just iron and copper. Copper doesn't care about volts, only amps. Don't overamp the copper and you have a happy motor. In order to get the RATED HP out of the motor, you must supply it with the rated voltage. Otherwise you will overamp the copper.