A.Dave Yates, a plumbing contractor in
York, Pa., responds: One way for corner-cutting hvac
installers to avoid clogs — and eliminate altogether the
expense of traps and condensate pumps — is to simply
drill a hole in the concrete floor and drain the condensate
directly into the stones under the slab. But this is a bad
idea, for a couple of reasons.
First, instead of clogging the drain trap on its way to the
condensate pump, the condensate will collect in the subslab. To
get rid of it, a pro will need to come and pull the line,
cement the hole shut, and — yes — install a
condensate pump and trap.
Second, terminating an untrapped condensate line in the
subslab zone creates a pathway for radon to be drawn into the
air stream and delivered directly to the living quarters. Even
if radon gas isn’t present, air streaming up through the
A/C coil can — through a weak venturi effect —
create a pressure differential that draws air in through the
condensate drain and blocks condensate from flowing out. The
condensate will overflow the drain pan and spill down onto the
furnace heat exchanger, shortening its life considerably.
Because condensate drain traps often clog, a close inspection
should be a routine part of an annual service agreement.
It’s not hard to pinpoint problems in the condensate
system: If the condensate pan under the coil is full,
it’s not cracked. If the condensate pump is not
overflowing, it’s either working properly or nothing is
getting to it from the AC pan. To test the pump, pour enough
liquid into the reservoir to trip its float switch and observe
how well it pumps. If the pan is overflowing and the pump is
working properly, the drain is clogged and must be
A clear bend and access ports make this condensate trap
easy to inspect and clean.
To make inspection and cleaning easier, we typically include
an access point at (or near) the condensate trap. We also like
to install condensate traps with clear see-through bends, an
easy access port, and a flexible brush to facilitate cleaning,
such as the EZ-Trap EZT-110 (see photo; 800/324-7832,
Such traps cost about $17 compared with about $15 for a
plain-Jane PVC trap.