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Screens on funace intake/exhaust PVC

Bill4427 | Posted in Energy, Heating & Insulation on October 2, 2006 08:15am

I recently had a high energy furnace installed with PVC pipe for the air intake and heat exhaust. The PVC sticks out of the side of the house and the guy who installed the furnace said not to put any screening over the pipe because in very cold weather (northern Illinois) condensation could collect on the screen, freeze and seal off the inlet or outlet.  I am afraid that the three inch pipe is going to look like a highway to heaven for squirrels and other varmints that want to get into the house. I can see how regular window screen might freeze up but I wonder if I could seal those holes with 1/2″ hardware cloth or even chicken wire. It doesn’t seem that holes that large would freeze up. Any info is appreciated. Thanks.

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  1. Stuart | Oct 02, 2006 09:35pm | #1

    I don't have an answer, but I do have the same concern...I just had a new furnace installed as well, and my HVAC guy told me the same thing when I asked about covering them with a screen of some kind. 

    Those pipes do look pretty inviting for squirrels or other critters, and I can imagine that when it gets cold outside the warm air blowing out of there will be especially attractive.

  2. User avater
    rjw | Oct 02, 2006 10:51pm | #2

    Yeah, I have the same concern, but it is extremely rare, for some reason.


    Youth and Enthusiasm Are No Match

    For Age and Treachery

  3. Tim | Oct 03, 2006 12:00am | #3

    I live in heavy woods about 100 miles wnw of Chicago, squirrels, mice and chipmunks galore. I have a furnace vent that is about 14" above grade, and in the 9 years I've been there, never had a critter in a furnance vent. I vented my gas water heater similar to the way domestic clothes dryers are vented, with no screen but with a back draft damper and wall cap. I've had icicles off of the furncae vent but never off of the PV water heater vent, it discharges hotter gases. Of all of the things that have found a way into the house and all of the places they used, never had a PVC vent violated. I wouldn't worry about covering it.

    1. BarryO | Oct 06, 2006 12:42am | #4

      Mine have weatherproof caps on the outside, with large-opening plastic screens (~1/2") facing downwards.

  4. User avater
    McDesign | Oct 06, 2006 12:45am | #5

    I've got two of those condensing furnaces; both have inlet & exhaust 2' off grade - never a problem in 13 years, here in squirrel central.

    Forrest

  5. bearmon | Oct 06, 2006 01:22am | #6

    Not an HVAC guy, but I've seen vents with down-turned PVC 45's with screening molded right into the fitting.  About 1/4 inch mesh, if I recall.  Maybe try plumbing/heating supply house in your area.  I've also seen many without. 

    I'm a landscaper with an eye for detail, so I notice these things when working around houses.

    Bear

    1. User avater
      rjw | Oct 06, 2006 02:31am | #7

      >>Not an HVAC guy, but I've seen vents with down-turned PVC 45's with screening molded right into the fitting. About 1/4 inch mesh,Those are on the intake side

      Youth and Enthusiasm Are No Match

      For Age and Treachery

  6. mikeingp | Oct 06, 2006 11:27pm | #8

    Here's a pic of the screening I made for mine, using 1/2" hardware cloth. I was concerned about leaves, not animals. I figured the hardware cloth flat over the opening might impede the flow of air, so I, in effect, multiplied the surface area by building the cylinder-shaped screens.

    However, if you look at the bottom screen, you can see it's mostly eaten away, not be critters, but I assume by whatever corrosive exhaust the furnace puts out. I never fixed it because keeping leaves out of the pipe that faces up was more important for me.

    1. Bill4427 | Oct 10, 2006 11:00pm | #9

      Good idea. Thanks a lot. And thanks to all the rest for ideas and help. Sometimes you just gotta love the internet.

      Edited 10/10/2006 4:03 pm ET by Bill4427

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