My Furnace is a high eff furnace with a power vent. There is a gurgling sound in the power vent pipe, when it is running. I noticed that the vent slopes up then has a 90 elbow then slopes down before it goes outside. I suspect water is being trapped should i fix this so the water flows back to the furnace so it can go into the drain.


There should be a slope so all the water can drain. With enough water in the pipe to gurgle the back pressure may cause the system problems including shutdown and early fan failure.

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  • Just to be clear, down slope so the water will flow back toward the furnace and into the drain. – Drew Bailey Jan 4 '19 at 1:57
  • Yes that way the condensate will drain and not cause back pressure that can cause low flow and shut down the fire box or two much back pressure causing more pressure on the bearings in the motor leading to early motor failure. – Ed Beal Jan 4 '19 at 3:14

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