The dryer is installed but the bypass valve is open: air goes around the dryer, not through it.

What you'll see

Water in the lines even though a dryer is installed. Someone opened the bypass valve for maintenance or testing and forgot to close it. Or the dryer was causing excessive pressure drop (maybe frozen or clogged) and was bypassed as a 'temporary' fix that became permanent.
Before you assume this is the problem

If the bypass is closed and air goes through the dryer but you still have water, the dryer itself isn't working. See: Dryer Not Achieving Dewpoint.

How to diagnose

  1. Check valve positions

    Most dryer installations have three valves: an inlet valve, an outlet valve, and a bypass valve. The bypass should be CLOSED during normal operation. The inlet and outlet should be OPEN. Check all three.

    Result: Bypass open = close it. Inlet/outlet closed = open them.

How to fix it

  1. Close the bypass and open the dryer valves

    Simple fix -- close the bypass valve, open inlet and outlet valves. If the dryer was bypassed because it was causing problems, fix the dryer first before routing air through it again.

Common mistakes

Temporary bypasses have a way of becoming permanent. Always tag or label the bypass valve with a reminder. If the dryer was bypassed due to a fault, create a work order to fix it -- don't leave it.

Parts & tools

No parts needed. Just valve positions.

Review safety precautions before starting →