Forum Discussion

Explorer

Oct 19, 2018

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

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

33 Replies

groundhogy
Explorer
Oct 19, 2018
hmmm...

There is a single blower motor with two fans. I guess one for the outside of the firebox to blow air over the firebox to the ducts, and the smaller to I guess evacuate the inside of the firebox?

If so, the inside fan would move air faster also.
SidecarFlip
Explorer III
Oct 19, 2018
Ductape wrote:
And it will change your air to fuel ratio. I would bite the bullet and replace the entire furnace.

How so? The burner and firebox is seperate from the room air blower and has nothing to do with blower speed or air.

I'd go with the faster motor and not be concerned. Corrosion issues are from sitting over years, not from running. At operating temp the firebox HX is plenty hot enough to burn off any condensation.
Ductape
Explorer
Oct 19, 2018
And it will change your air to fuel ratio. I would bite the bullet and replace the entire furnace.