Furnace blower motor RPMs modified... is faster ok?

[groundhogy]

CALLING ALL MECHANICAL ENGINEERS !!!


I found a form - fit - function replacement blower motor for my Suburban NT-30k furnace. (original no longer avail)

All except the rpms. The new one is 33% faster. I thought that this would be fine, but now I am thinking the fire box running cooler could cause water vapor to not be totally ejected from the fire box?

I have read about corrosive problems that need special design considerations in high efficiency furnaces.
Would these things happen in my case?

Am I thinking correctly or worrying too much?
I dont want to have a rusted hole in the firebox halfway through the winter.

Thanks.
gh

[overlander63]

A resistor will slow the motor down, as will a potentiometer. Reducing voltage to reduce motor speed is an accepted method. Just make sure the method used is rated for the current used.

[groundhogy]

Yes, I think reducing the RPMs is the best solution too.


Going to need several power resistors. Have to drop 4 volts and 60 watts to get supply voltage and RPMs down by 33%. That is if Vsupply and RPMs are linear.

[rmkrum]

A more efficient way would be a PWM adjustable speed control.

[groundhogy]

Yes, I have heard about using PWM.

What would this circuit look like?
Its got to take some heat.