A small amount of water, every day

In many towers, each unit has a fan coil: a cabinet with a blower and a water coil fed by the building's central heating and cooling loops. In summer, the coil pulls humidity out of the air, and that condensate drips into a pan and drains into a vertical line shared with the units above and below. In heating season, the same coil carries hot water.

When a pan cracks, the drain clogs with dust and biological slime, or the shared line backs up, a small amount of water spills over every time the cooling runs. Denver's dry air means condensate volume is modest compared with humid cities, which is exactly why these leaks hide: there is never a flood, just a slow wetting of the closet floor, the wall behind the unit, and sometimes the ceiling below. Valves and fittings on the heating and cooling supply lines can also drip, and those leak whether or not the cooling is on.

Terms you will hear

Fan coil unit
A cabinet with a fan and a coil that heats or cools a unit using water from the building's central system.
Drain pan
The tray under the coil that collects condensate. Cracks, rust and clogs here are a common source of slow leaks.
Condensate riser
A shared vertical drain line that carries condensate from stacked units. A blockage can back water up into several units.
Float switch
A safety device that shuts off cooling when water rises in the pan. Not every unit has one, and they can stick.
Isolation valves
The valves on the supply and return lines to a fan coil. Building engineers close these to stop a leaking coil.

If you suspect the fan coil

  1. Look and smell

    Open the access panel if you can do so without tools. Standing water in the pan, rust streaks, a musty odor, or damp carpet at the closet threshold are all signs.

  2. Turn the cooling off

    Switching the thermostat off stops new condensate from forming while someone investigates.

  3. Call building maintenance

    In many buildings, the engineer services fan coils or keeps a list of approved HVAC contractors. They can close the isolation valves if a coil or fitting is leaking.

  4. Have the wall and floor checked

    Ask for moisture readings behind and below the unit. Drywall in these closets often stays wet for a long time because there is little airflow.

  5. Ask about the riser

    If neighbors above or below report the same problem, the shared drain may be blocked, which is usually an association matter.

Questions to ask after a fan coil leak

  1. Is the fan coil in my unit owner equipment or association equipment under the declarations?
  2. When was the drain pan and condensate line last cleaned, and is there a schedule?
  3. Does my unit have a float switch, and was it working?
  4. Were the units above and below checked for the same problem?
  5. Did anyone check behind the closet wall and under the flooring, or only the visible pan?

General information for Cherry Creek, not a quote or professional advice. In an emergency, call 911.