Condensate Piping Tip

Tips and tricks for condensate piping setup in G7 furnaces

Having problems with double trapping? Want to know how to run successful condensate piping every time? Well, here are some tips that are key to helping you succeed with condensate piping.

There are four main rules to successful condensate piping:

  1. You must have a drain coming from the outlet of the inducer assembly.
  2. You need to drain down from the lower right corner of the collector box on the secondary heat exchanger.
  3. You must have a drain at the lowest point of the system.
  4. And, you must remember that any drain that exits the cabinet off the furnace must have a trap.

Now, there are different variations of what would be considered a trap. You could use:

  • A J loop
  • A standard P trap
  • Condensate tubing that loops back on itself and has been primed with water

However, you’ll want to avoid double trapping! Double trapping can make it so that the furnace won’t start up.

Double tapping is caused when the piping runs uphill and drains into a floor drain, basement drain or any other portion of the plumbing of the house that has a trap where you physically have put that into the trap of that drain. The second trap basically cancels out the primary trap that is located inside the furnace. You will no longer have a vacuum break, which will counteract the negative pressure that is being created by the inducer motor inside of the furnace.

This will result in…

  • Suspended water inside the furnace.
  • A pressure switch that will not close when the furnace is starting up,
  • Or a pressure switch that may only open up on you once the furnace has been cycling for several minutes

Another important concept is the condensate pump. Condensate pumps are particularly prevalent in attics and crawl space installations. For a condensate pump, you take the drainage tubing of your furnace and put it into the well of the pump. Note: if this tubing goes below the water level inside of the pump, the well of the pump itself will become a double trap, and the pressure switch will stay open on you!

Have any more questions about condensate piping? Let us know in the comments.

***NOTE: ONLY USE IF YOU ARE AN HVAC CONTRACTOR. If you are a homeowner trying to dip your toes into the DIY pool – STOP. Serious complications can arise when HVAC installations, repairs or maintenance are performed by someone who is unfamiliar with heating and air conditioning equipment. Drop the wrench, pick up the phone and call a professional.

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