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-   -   Inducer Vacuum Problem (http://www.diychatroom.com/f17/inducer-vacuum-problem-59601/)

RobertCan 12-19-2009 07:23 PM

Inducer Vacuum Problem
 
Hello there,
Thanks for taking the time to read this post. Any help would be appreciated.

Here is some basic information: I have a gas fired direct vent forced air furnace by Inter-City Products Corp. model number: CHLK075AF01. On the furnace, there is a Fasco A-137 inducer fan motor: number 7062-3136, type U62B1 P/N 20000101, rpm 3450.

Here is the problem: The bearing went on the inducer motor. I found a twin replacement -all informations from the original Fasco motor's label to this Fasco replacement's label are identicaland the rotation rpm's is the same. The old motor worked fine except for the noise it made when it turned on. Everything worked well. I replaced the motor and connected the two hoses and wires. I should mention that these motors have 2 hoses- a 1/4" hose for vacuum and 1/2" for moisture drainage. The inducer motor turns on when there is a demand for heat, however, this motor is not creating enough vacuum from the 1/4" hose to the vacuum switch.
I put back the old inducer to make it was still creating a vacuum and it was but the new one doesn't. I even tried to take apart both casings, measured all components, everything is exactly the same and still it doesn't work. I don't understand why this motor is not creating enough vacuum to activate the burner switch to give heat on this freezing cold day!
Any help or suggestions or ideas out there? Thanks in advance,
RobertCan

Marty S. 12-19-2009 07:49 PM

Rotation the same on both?

beenthere 12-19-2009 08:57 PM

Quote:

Originally Posted by Marty S. (Post 369476)
Rotation the same on both?

Thats my first question too.

RobertCan 12-20-2009 11:19 AM

Thanks for the reply.
Yes the rotation are the same as well as the rpm's. I walked in to the fasco dealer, put the old one on the counter and asked for the same. There is very little vacuum, just not enouph to activate the pressure switch.

beenthere 12-20-2009 11:27 AM

If everything is the same. Then take the new one back.

Yoyizit 12-20-2009 11:30 AM

It's almost impossible that the new one is designed incorrectly, so
does the new one have the same RPM and impeller shape as the old?

Is the impeller set screw loose on the new one?

If you block the output of either one the motor noise should change. Try this on both.

Check the current draw on both if you can. There is a formula somewhere linking power draw to CFM.

RobertCan 12-20-2009 11:34 AM

They find nothing wrong with it. Besides they are closed till Monday and we are in -19c (-2 f) weather with no heat in the house at the moment.

RobertCan 12-20-2009 11:38 AM

Hello Yoyizit,
I have no way to verify the rpm's exactly but seems to be the same. The tag indicates it is 3450rpm as the old one. I went as far as switching all the impleller and shell off of the old one to the new one to see if it makes a difference... nothing still the same. if i install the old one, even with a blown bearing it works.

beenthere 12-20-2009 11:43 AM

Either something IS different with the new one. Or it is defective.

I'd put the old one back on. And have them check the new one on Monday to see if its reaching its full RPM.

That way you have heat.

yuri 12-20-2009 11:43 AM

Is this a high efficiency furnace with plastic vent pipes? Are you replacing the entire inducer unit as one or just the motor? Post a pic of the furnace with both doors off and the inducer. I have seen lots of ICPs and pics make it easier for us to help.

Yoyizit 12-20-2009 11:48 AM

This is strange.
We are, fer' sure, going to learn something on this one, assuming we all find the problem.

To verify impeller speed match: cut a small piece of paper and have it hit the impeller edges. You'll hear a high freq. tone; for 10 blades on the impeller it should be about 600 Hz. It should be the same for both motors.
You confirm the freq. accuracy if you have a piano.
"D5" is close to 600 Hz
http://www.sengpielaudio.com/calculator-notenames.htm

RobertCan 12-20-2009 11:57 AM

Quote:

Originally Posted by Yoyizit (Post 369740)
This is strange.
We are, fer' sure, going to learn something on this one, assuming we all find the problem.

To verify impeller speed match: cut a small piece of paper and have it hit the impeller edges. You'll hear a high freq. tone; for 10 blades on the impeller it should be about 600 Hz. It should be the same for both motors.
You confirm the freq. accuracy if you have a piano.


Ok i see, but when i opened up shells, all the part numbers inside are the same. Besides I counted and measured them all, hights, depths, widths and circumferanc. put old and new parts back to back as well.

RobertCan 12-20-2009 11:59 AM

I am beginning to wonder, like Beenthere mentions, I think the rpm's are not the same. Even though the sticker indicates it is 3450rpm.

RobertCan 12-20-2009 12:15 PM

2 Attachment(s)
Here are two pictures. I hope it worked.

yuri 12-20-2009 12:19 PM

Are you changing the motor only or the whole plastic inducer and housing as one unit?


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