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Old 06-29-2010, 09:58 PM   #1
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


I just had a high efficiency Lennox furnace installed and both the through-wall exhaust and air intake pipe are open at the end ie. no bird or insect screen. Can some sort of a screen be added or will this screw up the furnace operation? Any suggestions on how to keep the critters out of the pipes would be appreciated.


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Old 06-29-2010, 10:22 PM   #2
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


A screen in the exhaust causes lots of no heat causes, when it freezes over.

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Old 06-30-2010, 06:06 AM   #3
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


A screen will freeze up and plug up with spider webs. These are good for scaring away the birds.
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Old 06-30-2010, 06:32 AM   #4
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Try to use street 45 on the exhaust; intake should have 90 on it, no glue, pull it out when below 30F.
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Old 06-30-2010, 09:06 AM   #5
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Do you think a cage similar to what is used on the end of a suction pump intake hose if the mesh was 1/4 or 1/2 inch would work without freezing up? Also, is the intake as critical say 1/4 inch mesh?
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Old 06-30-2010, 11:49 AM   #6
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Because the furnace is a High Efficiency, or condensing unit, there is a high moisture content on your exhaust. In the winter, during extreme cold, this condensate will freeze on the screening, and clog the screen.
What I did was put a 45 elbow on the output, but not glued. As soon as I was done heating for the season, I removed the 45, and installed a cap. I have a reminder warning on my system (label on thermostat and sign on the winter/summer humidifier baffle) to remove the cap when the heating season starts. If I forget, the backpressure will trip a code, and not fire the unit.
Without the cap I get bees building a nest. Not fun.
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Old 06-30-2010, 03:45 PM   #7
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Which Lennox unit did you have installed? I am a Lennox tech. You cannot obstruct or change the end of the exhaust pipe as it has a special fitting called an accelerator. If you alter the piping it will cause pressure tripping problems.
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Old 06-30-2010, 05:35 PM   #8
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Yep has to be straight out on a Lennox exhaust. Cover it after heating season and remove before firing up the furnace if it makes you feel better. Critters are not really an issue though
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Old 06-30-2010, 06:45 PM   #9
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


I installed a Lennox G61MPV-60c-111 natural gas 95% efficiency furnace at elevation 7,400 feet in Colorado. I was thinking about adding a 12 inch diameter by 8 inch long basket of 1/2 inch wire mesh clamped around the end of the 2-3/8 inch PVC horizontal exhaust vent and also covering the 4 inch PVC air intake opening with the same mesh. This would keep out the birds and but not the bees. I don't think the 1/2 inch mesh would ever ice up or restrict the exhaust vent? The reason for wanting to leave the vents open is to circulate air with just the fan during the summer months. What do you think?

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Old 06-30-2010, 08:22 PM   #10
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


"The reason for wanting to leave the vents open is to circulate air with just the fan during the summer months. "

Which vents do you mean? The PVC venting is only for the burner and not house ventilation. That is the larger size of venting and I actually had a bird fly in the exhaust of one and get as far as the ventor fan so it is possible. As long as you do not add to or alter the PVC pipes with elbows etc you should be okay. Mesh may be ugly but it will work if it just surrounds them. You do need to check them once a week and when it is snowing for any buildup or icing or hoar frost. That furnace is not overly finicky about venting and pressure switch tripping but you want to avoid it.
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Old 06-30-2010, 08:22 PM   #11
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


I bought some of that soft aluminum gutter guard from HD that you put over gutters to keep leaves out. The holes are large enough for air flow but small enough to keep critters and leaves out. I form fitted a piece over the intake and the exhaust pipes and have never had a problem. I am using 4 inch pvc with a run of about 15 feet. Been working just fine for years.
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Old 06-30-2010, 09:31 PM   #12
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Sorry I was not clear about the vent reference. You are right, the furnace intake and exhaust PVC vents have nothing to do with circulating the air with the furnace fan. I must have had a brain fa..t ! Anyway, thanks everyone for helping me and I am going forward with either 1/2 inch hardware cloth (mesh) or the suggested HD gutter leaf guard material to keep out the birds and leaves next fall. Meanwhile, I am going to cap both PVC pipes till then.
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Old 11-15-2010, 11:36 PM   #13
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


I put vent caps on my open PVC pipes. I have several trees which litter my roof with sticks and leaves (see http://www.fitthewondercap.com/). They were around $10 a piece and took a second to install.
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Old 11-16-2010, 03:13 AM   #14
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


Quote:
Originally Posted by DanCB View Post
I put vent caps on my open PVC pipes. I have several trees which litter my roof with sticks and leaves (see http://www.fitthewondercap.com/). They were around $10 a piece and took a second to install.

Looks like advertising.

They are also a code violation in many areas. When installed on the exhaust pipe.

I can see many no heat problems if its installed on the exhaust.
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Old 11-18-2010, 06:34 PM   #15
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High Efficiency Furnace Exhaust Vent-Need Bird/Insect Screen


I have had zero problems with it installed on my exhaust pipe. Also, the cap is CSA certified.

beenthere - I guess I should contact the site owner to see if I can get paid for my 'advertising'. lol

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