Results 1 to 13 of 13
  1. #1
    Join Date
    Mar 2005
    Location
    Waycross, Georgia
    Posts
    33
    I was wondering when putting in a 92+ furnace in place of a 80% furnace should I use PVC for the vent pipe? The old furnace has hard pipe for the vent. Why use PVC? I would like it if someone would explain this to me.

    Thanks, Brian Coggin

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,931
    The flue gases on a condensing furnace are well below 212F, usually around 100 degrees. You will have water running out the joints in the flue pipe and the acidic vapor chewing up metal vent pipe in no time. That's why it has to be PVC. On the 80s and lower, the flue gases are 300-500 degrees and much less moist so they can properly vent in metal. Now, there are many 80% jobs vented in single wall pipe that shouldn't be...any garage for example should be double wall by code and many other installations as well.

  3. #3
    Join Date
    Mar 2005
    Location
    Waycross, Georgia
    Posts
    33
    Thanks for the info.

  4. #4
    Join Date
    Apr 2004
    Posts
    7,680
    I'm trying to be carefull with my answer, no offence intended.

    In a previous post you mentioned you are new to the site but have been doing HVAC for 2 1/2 years. Welcome to the board.

    Now I'm having a little difficulty with understnding how one in his 3rd heating season doesnt know the difference between 80 and 90% furnaces yet wants to take on the job of installing one.

    Where are you buying the furnace?

  5. #5
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    You do have an installation manual and are using it for more than a knee pad, right?


  6. #6
    Join Date
    Mar 2005
    Location
    Waycross, Georgia
    Posts
    33
    Havn't got the unit yet buddies so I havn't read the installation manual. Live in the south. Don't ever put in Gas furnaces either. This one farther up north. Im use to Heat Pumps. I change a gas furnace its usually to a Heat Pump.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,776
    You do have some one with gas expereince helping you.

    Someone to set it up, right?
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Mar 2005
    Location
    Waycross, Georgia
    Posts
    33
    I know how to hook a gas furnace up. I've worked on a many of one. Just never put in a 90% furnace. Not a big demand for them where im from. I have no problem installing it. Only question I had was about the flue pipe. And one of you kind fellows answered that for me. Thanks.

  9. #9
    Join Date
    Apr 2004
    Posts
    7,680
    Hooking up and setting up are two completely different animals. Good luck

  10. #10
    Join Date
    Feb 2005
    Location
    Dothan, Al
    Posts
    3,453

    coggin air

    Where in the south u from ???

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,776
    Originally posted by docholiday
    Hooking up and setting up are two completely different animals. Good luck
    Doc, we're old and bald, we never never had that atittude,LOL...


    Coggin, so what meter do you use for combustion set up on the gas furnaces you installed.

    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12
    Join Date
    Mar 2005
    Location
    Waycross, Georgia
    Posts
    33
    Used a Kane 250.

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,776
    Ok, now don't the instructions for your meter tell you to drill a hole in the pvc pipe for 90+ furnaces.

    LOL...
    Just jerkin your chain, thats a nice tester.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event