Case at a glance

House
Single-story mid-century ranch, updated with central air
Hidden source
An idle rooftop evaporative cooler with a live water supply
Where it showed
Hallway ceiling below the old cooler register
Main lesson
Disconnect or remove equipment that is no longer used

What happens

Illustrative example. Not a real job or customer.

In this illustrative example, a couple buys a remodeled 1950s ranch near Hilltop. The house has modern central air, and the old swamp cooler on the roof is never mentioned beyond a line in the inspection report. The previous owners had capped the ceiling register with a decorative cover. During the first summer, a sour smell appears in the hallway, and by late summer a soft, discolored patch shows around the old register.

  1. The owners pull the register cover and find damp insulation and dark growth on the drywall edges around the duct opening.
  2. On the roof, a roofer finds the cooler's float valve stuck and its water line still connected; the pan has been overflowing into the cabinet and down the duct.
  3. The water supply to the cooler is shut off and the line is disconnected at the source.
  4. The owners decide to have the cooler removed and the roof opening properly framed, decked and roofed over.
  5. A remediation contractor contains the hallway, removes the affected ceiling drywall and insulation, cleans the ceiling joists and checks the attic for growth around the old duct.
  6. Once dry, the ceiling is rebuilt without any opening where the register used to be.

Removing the unused unit eliminated a recurring leak risk entirely, and the ceiling repair was limited to the hallway because the owners investigated the smell within the same season.

Keep the cooler or remove it?

Keeping an evaporative cooler

  • Economical cooling in dry Denver summers
  • Requires seasonal startup, shutdown and duct sealing
  • Water line, pan, float and pump need routine checks
  • Roof penetration must stay watertight

Removing an unused one

  • Eliminates a water source above living space
  • Requires closing the roof opening and the ceiling duct properly
  • May need a roofer and, for the water line, a plumber
  • Ends the need for annual maintenance on idle equipment

If your house has an old cooler

  • Find out whether it is still connected to water and power
  • Check the ceiling around its register for stains, softness or odor
  • Look at the roof below the unit for rust streaks or damaged shingles
  • Ask the inspection report or seller whether it was winterized
  • Decide deliberately whether to maintain or remove it

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