Draft blower on outdoor forced air furnaces

Woodcutter_Mo · January 03, 2018, 09:42:39 AM

The draft blower on my dad's outdoor furnace went out a little while back. He picked up a new blower but the motor is on the opposite side and the motor and fan is a bit bigger so it won't mount on the furnace due to clearance problems.

I had bought a new outdoor furnace a while back and it has the same blower as what goes on his, and we thought about just swapping mine out for the larger blower. Would having a larger blower on my furnace hurt anything?

Kwill · January 03, 2018, 02:24:01 PM

Mine doesn't currently have one although I've considered adding one. Do you have any trouble with sparks coming out the stack when the blower kicks in?

thecfarm · January 03, 2018, 02:30:50 PM

I have no idea. Does it draw anymore amps than the smaller one would be my concern. I have 2 blowers in mine,one in front and back. I have never seen sparks come out of my stack. But the Heatmor has a 3"x6" channel that goes from the back to the front than out the chimmey. And I also have a 9 foot chimmey too. That blowers is what makes the fire comes to life and lets me burn rotten wood and dry cedar. In between cyles,no air can get into the firebox.

Woodcutter_Mo · January 03, 2018, 03:10:19 PM

I haven't used my furnace yet, but my dad's furnace don't seem to blow sparks much that I've noticed anyway. I'll look at the specs on both blowers and post up what they say as far as amp draw goes ect. I'd think the larger one would draw a bit more.

Woodcutter_Mo · January 03, 2018, 09:00:49 PM

Quote from: Kwill on January 03, 2018, 02:24:01 PM
Mine doesn't currently have one although I've considered adding one. Do you have any trouble with sparks coming out the stack when the blower kicks in?

I talked to my dad about his and he said it can blow a few sparks out the chimney sometimes.

TKehl · January 03, 2018, 09:05:14 PM

As long as the draft blower is thermostatically controlled, the bigger one should be fine. Will just have shorter on cycles.

If it doesn't have a thermostatic control, it could potentially overheat the stove with too much air.

Do check the amperage, but I doubt there is much difference.

Woodcutter_Mo · January 03, 2018, 10:18:26 PM

That's kinda what I was hoping, wanted to make sure there wasn't something major I was overlooking. Both furnace draft blowers are indeed controlled by the thermostat. I'll try to get the specs from the two blowers and and a side by side comparison of them tomorrow.

gspren · January 04, 2018, 09:02:10 AM

My older P&M has an adjustable intake for the blower so you can control how much air is being blown in. As to sparks that's very brand dependent, some will a lot and some won't, I've never seen a spark from mine but have from a neighbors.

E Yoder · January 05, 2018, 04:33:28 AM

You should be able to google both model #'s and compare cfm's. Amp draw would get close but some put out more pressure than others.
Or post the model #'s here along with the owb model.

Woodcutter_Mo · January 05, 2018, 09:23:55 AM

Here are the specs on the 2 blowers.

Factory blower on my Fire Chief FC2200:
HP 1/125
CFM 50@free air
Hz 50/60
Amps 0.22/0.23
RPM 2700/3080

Replacement blower in question:
HP- 1/70
CFM- 75@free air
Hz- 50/60
AMPS- 0.40-0.45
RPM- 2700/3020

I'm thinking it will work fine as long as I adjust the slide plate on the blower intake accordingly as gspren mentioned. The CFM is a fair bit higher, so I don't know if closing the slide that far would restrict the motor too much?

Otherwise, the difference in amp draw should be ok shouldn't it? And it will mount to my furnace just fine and will be a direct bolt on replacement, just the motor is on the opposite side of the fan.

tawilson · January 05, 2018, 10:41:15 AM

My boiler has a rheostat to control one of the fans. Not expensive and would let you easily adjust your air flow.

dave_dj1 · January 06, 2018, 07:08:54 AM

just mount the new one he bought upside down.

Woodcutter_Mo · January 06, 2018, 10:45:37 AM

Quote from: dave_dj1 on January 06, 2018, 07:08:54 AM
just mount the new one he bought upside down.

He thought about doing that, but the bolt holes will only line up one way.

E Yoder · January 06, 2018, 05:43:40 PM

Throttling it shouldn't hurt it, just don't let anyone open it up or the extra draft might damage something .

Corley5 · January 07, 2018, 12:05:18 AM

Be sure the motors are rated for variable speed use. The one that my OWB uses came with a variable speed control but is not rated for such. I didn't find this out until I replaced the second one from an aftermarket source. This one is lasting much longer running at full speed than the others that I ran at a little more than half.

Woodcutter_Mo · January 07, 2018, 12:32:51 AM

Thats something I was wondering about as well. If I decide to add a rheostat I will make sure the motors are capable of variable voltage first. Thanks

We got the draft blower from my furnace installed on the furnace at my dad's place and the larger draft blower installed on my furnace today. I hopefully will be able to test it out in the very near future.