What Are Those Pipes Sticking Out of My House?

We’ve had many customers ask us what are those pipes sticking out of my house for. We also get questions like, “Can they be cut flush with the house?” and “Why are they pointing in different directions?”

To answer these questions and more, we will be discussing what those pipes are used for and why they must be installed the way they are.

It is critical that these pipes remain clear; otherwise, you could risk having leaking condensate damage your furnace and your home.

For this reason and many more, it is highly recommended that you have annual heating maintenance done by a trained HVAC professional.



A furnace that burns natural gas in order to heat your home produces combustion gases as byproducts and these byproducts need to be vented out of your home. A conventional furnace (under 90 percent efficiency), releases combustion gases through a vertical vent that is attached to your system.

Most furnace systems have a 2-pipe system where one pipe intakes fresh outside air and the other vents flue exhaust gases to the outside.

There are specific manufacturer guidelines that require the piping to be a minimum distance away, which is why they are placed the way they are, with one facing in a different direction from the other. They also have to be high enough off the ground to help reduce the risk of snowfall blocking the pipes.

Make sure these pipes have a minimum clearance of 5 feet.

In addition to these assembly guidelines, category 4 furnaces can only use 3 types of plastic pipes: PVC, CPVC, and ABS.

While it may be tempting to hide, plug, or even cut the PVC pipes so that they’re closer to your home and less of an eyesore, these pipes are there so that proper venting can occur, which is necessary for your health and safety as well as the functionality and efficiency of your furnace. Needless to say, these pipes should never be altered or adjusted unless done by a trained HVAC technician.

If you really can’t stand the sight of these pipes sticking out of your house, consider a dormant winter plant so that it does not get harmed by the furnace exhaust.

Call us at 515-657-6634 for more information on how your HVAC system works!

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And a big thank you for making Service Legends the #1 provider of residential heating and air conditioning in the Des Moines area.