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  1. #1
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32

    Running two 2" PVC pipes thru one 8" existing roof opening . Whats the best way ???

    I have an existing 8" roof opening which the previous 65% gas furnace
    and water heater was vented thru . The last owner abandoned both and
    went with electric furnace and electric water heater...and simply
    placed an 8" sheetmetal cap over the roof opening .

    I want to install a 95% gas furnace requiring two 2" dia. PVC Pipes
    (intake and exhaust) and would like to utilize the present 8"roof
    opening . I could cut two seperate holes thru the existing cap ,
    or, is it better to use one rubber roof jack for both pipes to go
    thru if such a thing is offered ? I want to have it sealed good
    against the elements.


    Your help is appreciated
    .

  2. #2
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Quote Originally Posted by JustCallMeDave View Post
    I want to install a 95% gas furnace requiring two 2" dia. PVC Pipes (intake and exhaust) and would like to utilize the present 8"roof opening . I could cut two seperate holes thru the existing cap , or, is it better to use one rubber roof jack for both pipes to go thru if such a thing is offered ? I want to have it sealed good against the elements.
    You'd probably want to get a concentric vent kit.

  3. #3
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32
    Quote Originally Posted by b26440510 View Post
    You'd probably want to get a concentric vent kit.
    So a kit where you have a pipe within a pipe to handle exhaust and intake ? The entire kit is then put thru the roof opening then sealed , i take it ??? Ill do a google to see what that looks like. Thanks.

  4. #4
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    You might want to run the cocentric offset in the existing pipe and not centered incase you want to get a direct vent gas hot water heater in the future.

  5. #5
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32
    Quote Originally Posted by motoguy128 View Post
    You might want to run the cocentric offset in the existing pipe and not centered incase you want to get a direct vent gas hot water heater in the future.
    That would be a valid concern, except, I made myself a Solar Hot Water Collector which is giving me some mighty hot water of 145-160 f. ... enough for a daily shower and dishwasher , so I dont use my water heater anymore -- living in FLorida has its advantages :

    (http://rimstar.org/renewnrg/diy_pex_...thermal_dn.htm ) .

  6. #6
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Quote Originally Posted by JustCallMeDave View Post
    So a kit where you have a pipe within a pipe to handle exhaust and intake ? The entire kit is then put thru the roof opening then sealed , i take it ??? Ill do a google to see what that looks like. Thanks.
    Yeah, basically turns the two pipes into one. They are make/model specific so check which ones are compatible with your equipment.

  7. #7
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,485
    Or get an Alumi-flash pipe portal. You can run four 1" to 2" pipes through it, but nothing really hot (i.e. nothing requiring a metal vent). The base is aluminum and it has a EPDM cap. They have one with a single 2" to 6" cap too, if you want to run the concentric vent through it.

  8. #8
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32
    Ill google the alumiflash pipe portal to see what is looks like . Thanks

  9. #9
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,042
    I think I would replace the shingles/decking in the area, and put a new flashing at another spot.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  10. #10
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,485
    Quote Originally Posted by JustCallMeDave View Post
    Ill google the alumiflash pipe portal to see what is looks like . Thanks
    Manufacturer is Commercial Products Group:
    http://www.commercialproductsgroup.c...lumiflash.aspx

    Or check the Big Rock Supply web site.

  11. #11
    Join Date
    Apr 2011
    Location
    North Florida
    Posts
    32
    Quote Originally Posted by garya505 View Post
    Manufacturer is Commercial Products Group:
    http://www.commercialproductsgroup.c...lumiflash.aspx

    Or check the Big Rock Supply web site.
    Great. Thanks.

  12. #12
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    wow, those seem to be more for industrial. Would anyone need 4/5 vents in one location for a house?

    Looks like maybe the portal line would be a bit more practical.

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by b26440510 View Post
    wow, those seem to be more for industrial. Would anyone need 4/5 vents in one location for a house?

    Looks like maybe the portal line would be a bit more practical.
    Sure, 2 gas DV fireplaces, DV hot water heater, 2 furnaces. Not a bad idea to have just a single roof penetration. The fewer holes you can put in a roof the better.

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