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  1. #14
    Join Date
    Mar 2004
    Location
    Gone
    Posts
    5,340
    You need to call your technician back out to perfrom and check these critical measurements. We can not give step by step instructions such as adjusting heat rise on this site.

  2. #15
    Join Date
    Oct 2005
    Posts
    5
    I was not asking for step-by-step instructions for adjusting heat rise. I have already called my installer, and he is coming out to investigate and adjust the settings. I am just interested in conceptually how you go about setting the blower speed.

  3. #16
    Join Date
    Nov 2004
    Posts
    2,927
    Yes,you have the basic idea of it...the rest of the info (specifications) are published by the manufacturer,and should be available.

  4. #17
    Join Date
    Jul 2004
    Location
    midwest
    Posts
    2,868
    I know you say its in the furnace but it sounds like a noise you get when return grills are undersized. Try taking the return grills off and see if it goes away. It would seem to me that any problem with the blower wheel would be obvious at start up.

  5. #18
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,516
    does the unit have a central return grille. i have seen many cases where the grille humms and sounds like it is coming from the blower. if this is the case changing the angle of the finns may help. this may sound strange to you but it is not uncommon to think this noise is in the blower because of echoing in the duct

  6. #19
    Join Date
    Oct 2005
    Posts
    923

    Noise

    Check the vent and flue, sounds like it could be restricted. Has it been cleaned?

  7. #20
    I have heard of this problem occurring with many different manufacturers. You should NOT have noise like that at any speed. Blower wheels are not made like they used to be and subsequently they can literally "vibrate" apart because they have a resonant frequency too close to the torsional resonance of the motor itself. Solutions include moving the motor shaft axially to alleviate the resonance or sadly replacing the wheel. It is important to note that if there is extremely high static pressure that it can cause resonance regardless of motor position and must be addressed. Paste the address below into your browser to read more about this problem and how it is remedied.

    http://www.sandvmag.com/downloads/0105zeng.pdf

  8. #21
    Join Date
    Oct 2005
    Posts
    923

    Noise

    Just had the same thing happing and found several brick blocking the exhaust flue. Unit was working to hard and making lots of funny sounds. At first thought it was the motor or fan but that all checked out.

  9. #22
    Join Date
    Nov 2004
    Posts
    2,927

    geez ,cool runnings

    Originally posted by coolrunnings
    Solutions include moving the motor shaft axially to alleviate the resonance or sadly replacing the wheel. http://www.sandvmag.com/downloads/0105zeng.pdf
    I try would changing set screw to rotor length...

    before trying to understand what all that was about!

    but thanks anyway.

  10. #23
    Join Date
    Jun 2000
    Location
    WYO
    Posts
    2,019
    The grill resononce is one possibility. If the furnace vibrates when the blower is on (feel the furnace) the blower wheel is out of balance for some reason.
    Have the tech determine the proper heat rise @ quit playing with it yourself.
    Could be the motor too.None of us can solve this online.Your tech is coming back and you like him.Write back if he doesnt solve it,but give him the first chance.
    never say never

  11. #24
    Join Date
    Mar 2004
    Location
    CHICAGO SUBURBS
    Posts
    464
    You might have duct size and/or configuration issues.A VS fan system is going to deliver a rated volume according to dip switch settings no matter what and sometimes that will cause some nasty noises if duct isn't right.
    Some people swear by me and some at me

  12. #25
    Join Date
    Jan 2004
    Location
    Here and there
    Posts
    4,808
    Not meant to offend any one, but was the shipping bracket removed?
    i belong to peta ... people eating tasty animals. all my opinions are just mine.

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