Venting High Efficiency Furnace


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Old 10-14-20, 07:16 AM
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Venting High Efficiency Furnace

Hello,
I need to raise my intake & exhaust pipes for my high efficiency furnace. I am attaching my current configuration.


If I add 90 degree elbows upward, the intake side would not be draining to the outside. What is the solution to this? This is what want to change it to:


Of course the upper elbows would be aimed away from each other.
 
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Old 10-14-20, 10:06 AM
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The first thing to do is read your furnace's Installation Instructions. Manufacturers are quite specific about how this is to be done. You'll then need to measure the existing lengths of piping and count the number of elbows to make sure the end result - with additional pipe and elbows - is within the "MAXIMUM TOTAL EQUIVALENT FEET" permitted. Here's an excerpt from an old Trane Installation Instruction. Good luck!

 
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Old 10-14-20, 12:26 PM
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Thanks ferd42 but Iíve already taken all that into consideration. Iím well within the specs. My question is, on the intake side, how does it drain if the elbow takes it upward? I see them all the time where they are brought up with an elbow but I never see a drain at the bottom of that elbow. Right now it drains through the end of the pipe but putting an elbow on it takes away the drain ability.
 
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Old 10-14-20, 03:19 PM
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Maybe I misunderstand - but I believe that the inside inlet pipe is usually pitched either downward toward the furnace or downward toward the outside? An outside drain could freeze up and clog?

By the way, when they say that the inlet and outlet should be positioned 12" above the expected snow level, that distance needs to allow for heavy drifting of snow, which is hard to predict. The heaviest drifting will occur in strong winds with inlet and outlet pipes that are leeward of an exterior wall. Here in the Midwest, I've encountered drifts of over 4 ft alongside exterior walls. The drawing posted by ferd is very helpful, but a drawing dimension shows the the pipes at 12" elevation. The written description clarifies that it is 12" above expected snow level.
 

Last edited by gilmorrie; 10-14-20 at 03:47 PM.
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Old 10-14-20, 04:08 PM
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Thanks gilmorrie. My exhaust is pitched toward the furnace and drained at the furnace. The intake is pitched toward the outside so now it just drips out the end of the pipe but if I add an elbow it wonít drain.
 
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Old 10-15-20, 02:50 AM
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Does your manufacturer permit the intake to rise? The Trane diagrams do not show that as an option.

If your furnace is listed for one pipe operation (Trane permits one and two), you could convert to one pipe, assuming it's in an "Unconfined Space".
 
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Old 10-16-20, 02:25 PM
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Sorry, I had the lines mixed up. Itís actually the exhaust pipe that drips. Which is sloped towards the furnace and thereís a drain on the furnace end. So it really shouldí matter if I raise them. Correct?
 
 

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