Author Topic: Pvc exhaust flue screen ???  (Read 479 times)

Offline wantboost

  • Pro Tech™
  • *****
  • Posts: 55
Pvc exhaust flue screen ???
« on: July 05, 2018, 07:30:40 PM »
I've seen two types of screens ones like a mesh the other is large wide grill . I guess to block birds. 
The screen type blocks exhaust and causes issues. 
.  Is the other type that blocks birds a good idea to have ?

Offline Admin

  • Administrator
  • *****
  • Posts: 2232
    • HVAC TECH GROUP
Re: Pvc exhaust flue screen ???
« Reply #1 on: July 05, 2018, 07:46:33 PM »
Yes, flue gas recirculation sometimes causes problems in the winter on vents with screens.  Some appliances come with plastic screens, and you have to install the correct one based on venting length.  I would read the installation manual.  Modying the screens could affect the pressure switch.

For example the Lennox EL296XE manual says,

Quote
Do not use screens or perforated metal in exhaust or intake terminations. Doing so will cause freeze-ups and may block the terminations.

The Building Code does say that all intake and exhaust vents outside must be fitted with a screen with openings not larger than 15mm, and only dryer vents are exempt.  The Building Inspector seems to accept what the appliance installation manual says and does not enforce screens.

Offline wantboost

  • Pro Tech™
  • *****
  • Posts: 55
Re: Pvc exhaust flue screen ???
« Reply #2 on: July 05, 2018, 10:04:04 PM »
If not putting any. What's the chances of bird rodent etc  coming in ?

Is this the ones that are ok . Ie 15mm

https://www.homedepot.ca/en/home/p.3-inches-termination-vent-screen.1000655633.html

Offline NoDIY

  • Pro Tech™
  • *****
  • Posts: 67
Re: Pvc exhaust flue screen ???
« Reply #3 on: July 05, 2018, 11:03:33 PM »
slim to non..

in 20 years i have seen a birds nest once inside a carrier and sandwich bag in a pulse muffler once....

Offline wantboost

  • Pro Tech™
  • *****
  • Posts: 55
Re: Pvc exhaust flue screen ???
« Reply #4 on: July 05, 2018, 11:18:36 PM »
Alright I wont out one then

slim to non..

in 20 years i have seen a birds nest once inside a carrier and sandwich bag in a pulse muffler once....

Offline walker

  • Pro Tech™
  • *****
  • Posts: 515
Re: Pvc exhaust flue screen ???
« Reply #5 on: July 06, 2018, 12:52:31 PM »
I've found - rocks, golf balls, peanut shells, acorns, plastic bags in intake pipes.  rocks and golf balls were from kids, peanuts, acorns, nuts were from chipmunks, and plastic bag was just a fluke.

Offline wantboost

  • Pro Tech™
  • *****
  • Posts: 55
Re: Pvc exhaust flue screen ???
« Reply #6 on: July 06, 2018, 04:50:45 PM »
Wow lol maybe I should . It's a rental property.  Is the one I showed in the link the proper one?

Offline Admin

  • Administrator
  • *****
  • Posts: 2232
    • HVAC TECH GROUP
Re: Pvc exhaust flue screen ???
« Reply #7 on: July 06, 2018, 05:39:55 PM »
That IPEX screen has openings smaller than 15mm so it would satisfy the Building Code.  Just make sure the appliance manual does not say you can’t install a screen.

Offline Hvacpimp

  • ***
  • Posts: 41
Re: Pvc exhaust flue screen ???
« Reply #8 on: July 08, 2018, 01:10:50 PM »
Just keep in mind that if the screen openings are too small, in the winter time when the condensation from the exhaust freezes up it could act like a barrier and screw with the pressure switch. I've seen it happen.