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  1. #14
    Join Date
    Sep 2006
    Posts
    41

    Hmm

    A short radius elbow is equivalent to 10' of 3" pipe. A long radius is equivalent to 6' of 3" pipe. Do you still come up with your 70'?

  2. #15
    Join Date
    Oct 2007
    Location
    Mount Gilead, Ohio
    Posts
    170
    4 long radius 90s figured at 5' each so w/ your formula 74' I have not seen the install yet but im sure im gonna end up w/ this one. Install dept always turns there problems over to service

  3. #16
    Join Date
    Apr 2004
    Posts
    7,680
    Quote Originally Posted by tinmantu View Post
    Make sure the vents are correct, then use a magnhelic gauge to test the pressure switch.
    Absolutely.

    I find it hard to believe TRANE is sending a factory guy out without someone at least giving up actual pressure measurements. What is your pressure and what is the switch rated at?

    Look, by pulling the fresh air you actually would decrease the negative pull on the furnace's HX, not improve it. However if your vent is restrictive, you may have hit full blower curve on the inducer indicating something is wrong with either a sag, an obstuction, short sweeping ells, or simply too long. You may also be trying to vent into a head wind.
    Last edited by docholiday; 11-09-2007 at 11:43 PM.

  4. #17
    Join Date
    Dec 2004
    Location
    Chicago area
    Posts
    1,439

    Pipe termination

    Many installers today dont look at instructions. I would guess that if all the piping is new, then the problem is how the piping terminates, IE exaust to close to intake, causing reduced pressure differential to satisfy the pressure switch.

  5. #18
    Join Date
    Nov 2007
    Location
    NC
    Posts
    137
    Is it possible that on the new installation a screen of some sort was added to the end of the flu pipe. I've had a install crew put a screen on that did not allow enough air to flow out and kept kicking out the pressure switch.

  6. #19
    Join Date
    Mar 2003
    Location
    North St Paul MN
    Posts
    858
    Quote Originally Posted by sandpipertech View Post
    Is it possible that on the new installation a screen of some sort was added to the end of the flu pipe. I've had a install crew put a screen on that did not allow enough air to flow out and kept kicking out the pressure switch.
    A good point sandpipertech, but if they haven't fixed it by now, theyr'e probably froze to death......this thread is 1 1/2 years old.
    I'd rather have a bottle in front of me, than a frontal lobotomy.

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