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90% PVC Vent Question

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  • #31
    Re: 90% PVC Vent Question

    Originally posted by proplumb View Post
    have you ever dealt with an inspecter? for an inspection the manual must be preasent as a referance. clearences are followed from the manuals. that clause is not ever followed as written, the otherwise approved is the rule as you should know. by the way try using the new code book not the 05'
    Simmer down sunshine I was just stating what the code says. I know that its not followed to the letter. The new code has the same clause.
    You will never expand your mind, if you do not challenge your beliefs.

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    • #32
      Re: 90% PVC Vent Question

      Originally posted by Evil Gopher View Post
      I still shake my head when I see PVC vent pipe on a gas furnace...yes its code approved..but my fussy mind cant accept PVC pipe on a gas furnaces..its hot..pipe will melt...I know it does not...but just seems soo wrong.

      We tie our PVC vent pipes into the existing flue/vent pipe dureing change outs sooo we do NOT replace the though the roof part....but make sure its got some kind of cap on keep rain and plumers out.
      Yes its hot, but it is forced out by a purge fan, basically moving the hot gasses out fast enough for less heat to be transferred to the pipe. PVC will hold up to temps higher than you think. As far *** needing a rain cap - negative! A condensing furnce has a drain to remove condensation from inside the exhaust pipe, as well as any rain if a roof termination. How are you guys getting passed sticking them out a B-vent? I assume you are working for/at a "fly by night" hvac company. ANY time you change from a furnace using B-vent to a high efficincy unit using pvc to vent, you can terminate out the side or the roof. Some type of drain or pump must be used to drain off condensation from the exhaust and any rain entering the vent.


      • #33
        Re: 90% PVC Vent Question

        Originally posted by 'Stormin View Post
        I just noticed that HVAC guy put the 3" PVC vent pipe up through roof but it doesn't have the "Candy Cane" or any cover so rain can go straight down it just like a plumbing VTR.

        Is this a mistake? Or is this a new correct way to do it? There is a small PVC drain combined with the A coil drain in case that helps answer.

        If it needs correcting should I just glue up a "Candy Cane" or is there a better method to keep rain out?

        There is a small PVC drain combined with the A coil drain in case that helps answer.

        Thats what its there for: to drain condenstion from the vent and any rain water that comes down the pipe. No rain cap is needed, when the furnace is running, condensation is draining on a high efficancy 90+ furnace using pvc vent!


        • #34
          Re: 90% PVC Vent Question

          Another manufacturer on system 636 pipe is Royal...which is what I used...pipe, fitings and glue, all one system (don't mix pipe, fittings or glue when dealing with flue exhaust). If you are worry about pipe melting (as an earlier post), then you should worry MORE about HOT water melting PVC pipes than 90% eff. furnace exhaust. Put your hand on the exhaust coming out of the PVC pipe will NOT burn water(depending on the temp) will!!!
          Incidentally, the 90% 100,000 BTU Keeprite units require 3" pipe no matter how short the run is.

          As for connecting the PVC vent to existing metal pipe- THAT'S CRAZY!!!!

          More info on Royal:


          • #35
            Re: 90% PVC Vent Question

            Oh regarding the rain cap....what is MORE important than a rain cap (which is not really needed by the way since the consendate will cool, drip, and drain all the time anyway) is a SCREEN which will prevent LEAVES, BIRDS, and SQUIRRELS from getting down the pipe.