Furnace Not Blowing Hard

frenchelectrican

Not always the case sometime you have to look at the motour nameplate some case they will stated multi speed as well I know some belt drive motor will have mulit speed useage.

Of course the direct drive will have multi speed useage.

If you really need multi speed motour you can swap the motor and get one with higher RPM verison depending on the nameplate and use the adjustable pully to get the speed where you want it.

And some furnace they will have addtional relay to change the speed of blower as well.

Merci.
Marc

fabrk8r

Did you check for proper rotation as was suggested in your other thread on this subject?

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Scuba_Dave

2 threads on same issue merged

diyordie

@fabrK8r: I don't recall seeing any label about direction of rotation but I'll look again. I'm pretty sure the blower was going clockwise when I looked at it last but now I'm not so sure. If it is moving clockwise I'll try re-wiring to see if it makes an improvement. Now I'm kind of glad the furnace guy I called, who is a "good friend" of my mother-in-law, didn't return my call.

The motor only states 1725 rpm.

@frenchelectrician: I don't want to try a higher rpm motor than what is currently there for fear of damaging the bearings/belt/pulleys/etc. Is there any way to determine if the existing motor simply isn't operating at its design speed?

Please excuse the duplicate posts (HVAC and Electrical) but I wasn't sure where the problem truly was and I've recieved a lot of great feedback from both forums.

Thanks again for everyone's help.

frenchelectrican

Ok I can see what you mean and the motor is allready at 1725 then you can get adjustable pulley and can make it run little more faster IIRC the squrell cage blower can run little more faster but not a whole alot more without increasing the motor size that something you may have to watch on this one and one of the HVAC guys may confirm what my idea if so ., they will leave a instruction on that matter.

If you have adjustable pully then close up the gap a bit that will speed up a little more quicker but just watch the current drawage to make sure you are not excessing over what the motor nameplate stated { this item you may want to get clamp on ampmeter ask one of your freind or get one at big box store I do not know what the cost currentlly in USA due I am in France for quite a while }

Merci.
Marc

diyordie

Well, I haven't had a chance to check the rotation yet but I am mildly optimistic that this could be the problem. I don't know the etiquette for posting links on this forum but here goes...http://www.nyb.com/rotation-discharge.asp. This is from a company called New York Blower. They make industrial fans for stuff like dust collectors, process dryers, etc.. The diagrams seem to confirm what the rotation direction should be for a blower and if mine is running clockwise from the view shown in my pics, it is running backwards.

My major concern is that the direction specification for my motor says "Selective CCW". I'm not sure what this means. Is the motor reversible or not? Here is the specificaiton sheet for my motor I found on the manufacturer's website. http://www.marathonelectric.com/MMPS...em=048S17D2086
There is a link to a PDF drawing and wiring diagram on this page which indicates which leads to switch to reverse the motor but the connection diagram doesn't explicity name my motor so I want to verify that it is reversible before attempting to rewire.

a7ecorsair

Looking at the picture in your earlier post, I'd say the squirrel cage fan should run clockwise as viewed in the picture and that would mean the motor would run CCW as viewed from the live shaft end.

beenthere

There should be instructions on your motor for which wires to change to switch rotation.

diyordie

I'm getting conflicting info. Who's right?

fabrk8r

Reverse the rotation and check the air flow. You'll know instantly if it's better. It'll take 5 minutes.

A squirrel cage running backwards produces about 25% of the air flow it should when turning the proper direction. Feel the air flow at the blower with your hand. Switch 2 wires on the motor, start it and see if you feel more air being pulled into the blower.

BTW...for safety's sake. Disconnect the power first...just sayin' (because I've heard some stories on here lately...LOL).

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"The physician can bury his mistakes, but the architect can only advise his clients to plant vines." -- Frank Lloyd Wright

diyordie

I just realized my pictures from near the beginning of this thread don't really show the layout of the blower all that well. From the viewpoint of the pictures my blower looks like the "Bottom Horizontal"/"CCW" configuration shown in the New York Blower link above.

beenthere

Looking at the wheel from the pic you posted. The wheel should be spinning counter clock wise.
Look at the blowers in that link you posted. It shows the same thing I'm telling you.

fabrk8r

This is becoming a lot harder than it needs to be.

__________________
"The physician can bury his mistakes, but the architect can only advise his clients to plant vines." -- Frank Lloyd Wright

beenthere

ts the internet. Of course it is.

yuri

Wait until we get a discussion on how to determine the rotation of a oil burner pump and describe it.

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