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My furnaces draft inducer blower sounds like a snow blower running, so I set out to replace it. Finding a replacement part proved difficult, but I found a site advertising a compatible part and purchased it online.

My current blower runs at 2800/3200 RPM and is rated for 1/30 HP. The new unit is 2300/3000RPM and 1/25 HP. Otherwise, the two units are identical size, layout, etc.

Can I use the new blower as a replacement and is there anything I need to watch out for, such as the pressure sensors?

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I found this statement from the manufacture (Fasco) of my old and replacement part:

The blower is designed to produce a certain amount of air-flow measured in CFM (cubic feet per minute). The airflow in some furnaces is needed to create a specific amount of vacuum at the vacuum tap mentioned above. If the replacement blower is not the exact one needed but “looks close,” it may produce a lesser vacuum at the vacuum tap. This may not allow the furnace to operate since the furnace will not think the induced draft blower is operating

So the answer is, it depends on if the replacement part will generate enough CFM to trigger the pressure switches. In my case, the replacement is slightly more powerful (higher HP), but runs slightly slower (RPM).

Happy to report that in my case, the new motor did indeed work correctly.

  • You're putting a lot of faith in the pressure switch being able to cut off at exactly where it should. But the manufacturer had better of used a large safety factor (I'd be fine with it as long as it worked, though). AFAIK, HP is irrelevant (electric motors are dumb; they do the load you ask them to and just suck more juice) CFM is calculated based on the blade and the RPM; the load encountered will denote your HP draw. As you note, you only have to look at the CFMs (the blades are integral in a power-vent). – Mazura Apr 11 '15 at 3:06

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