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  1. #14
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by timjimbob View Post
    This is a power draft, not induced draft,system. You cannot tie this to any other vent.
    And it has B-vent?
    If more government is the answer, then it's a really stupid question.

  2. #15
    Join Date
    Jan 2006
    Location
    Powell River, BC, Canada
    Posts
    763
    What is the model # of the furnace? I worked for Carrier/Bryant dealers for almost 15years and never saw a true 'power vent' model. What kind of 'power draft' are you talking about? B-vent is NOT allowed for positive pressure venting so unless the 'power vent' is right at the termination and pulling through the entire length of b-vent it is illegal and potentially dangerous! Canadian code for b-vent termination is minimum 2' from the roof penetration (on the high side if a sloped roof) AND 2' above anything in a 10' radius.
    Where are you? Are you done yet? I got ONE more call for you.....

  3. #16
    Join Date
    Oct 2002
    Posts
    1,278
    gasguy, combustion blower is in the furnace. This, I assumed, created a positive pressure up the B vent.
    I have no model #. When it is 150 degrees in the attic, heat problems can wait!

  4. #17
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,893
    Quote Originally Posted by timjimbob View Post
    gasguy, combustion blower is in the furnace. This, I assumed, created a positive pressure up the B vent.
    I have no model #. When it is 150 degrees in the attic, heat problems can wait!
    Just a standard induced draft furnace then. The B vent is a negative pressure vent. So the height above the roof and anything within 10 foot of it is very important.

    Its probably tripping the rollout as said by others. And the venting needs corrected.

    Being so close to the roof, wind can cause a down draft.
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  5. #18
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by timjimbob View Post
    gasguy, combustion blower is in the furnace. This, I assumed, created a positive pressure up the B vent.
    I have no model #. When it is 150 degrees in the attic, heat problems can wait!
    That is just a regular induced draft furnace, not a power vented furnace.
    Since it is a Carrier furnace, the limit control that is tripping is likely the vent temperature limit.
    With an improperly terminated vent system, the vent temperature limit tends to trip when wind conditions are interfering with the drafting of the vent system.
    If more government is the answer, then it's a really stupid question.

  6. #19
    Join Date
    Oct 2002
    Posts
    1,278
    I still have alot to learn. Is bvent under positive pressure?

  7. #20
    Join Date
    Jan 2006
    Location
    Powell River, BC, Canada
    Posts
    763
    NO. The draft inducer fan is only meant to overcome the resistance of the HX. It's called induced draft as it pulls the gasses through the HX from the exhaust end as opposed to a power burner (think oil burner) which pushes in from the burner end. I agree that you need to lengthen the b-vent and you may need to install a high wind style cap.
    Where are you? Are you done yet? I got ONE more call for you.....

  8. #21
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,103
    Lol... Terminology...,
    Code up here stipulates 6" above expected snow level so we go 24" minimum off the roof. It sounds like a high wind cap is a good idea.
    Do you have adequate combustion air supply in the room? Should be 5" is your inducer fan working properly? Those inducer fans on the carrier mids like the pav/wav and tua tend to get tight bearings over time.... Check your draft at the pressure switch when the furnace is running.
    Given that your vent is so short, is it possible the vent is undersized?

  9. #22
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    I had a crown boiler with a bad spill switch right out of the box, is it spill or rollout? I don't remember if I read which one it was.

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