A swamp cooler usually leaks because the float valve is stuck or set too high, the water pan or reservoir is cracked, the bleed-off or drain line is blocked, or water is getting past the cooler's curb on the roof. Shut off the water line to the cooler, find where the water escapes, and fix it before it reaches the roof deck and ceiling.
Key takeaways
- A stuck or badly set float valve is the most common cause.
- Rooftop cooler leaks often show up as a ceiling stain inside.
- Mineral scale from hard water clogs valves, pads and drain lines.
- Drain and shut down the cooler at the end of each season.
How does a swamp cooler use water?
An evaporative cooler pulls hot outside air through wet pads. A small pump moves water from a pan at the bottom up to the pads, and a float valve refills the pan from your water line. Because water evaporates and leaves minerals behind, most coolers also have a bleed-off line that drains a little water to flush out scale. Any of these parts can leak.
Why is my swamp cooler leaking?
| Cause | What you'll see | Fix |
|---|---|---|
| Float valve stuck open or set too high | Water overflowing the pan | Free or adjust the float, or replace the valve |
| Cracked or rusted water pan | Water dripping under the cooler | Seal small cracks or replace the pan |
| Clogged bleed-off or overflow line | Pan overflowing during use | Clear scale and debris from the line |
| Loose water supply fitting | Drips at the supply connection | Tighten or replace the fitting |
| Worn pads or misaligned pad frames | Water spraying or dripping outside the unit | Replace pads and seat frames properly |
| Failed seal at the roof curb | Ceiling stain under the cooler | Reseal the curb and roof penetration |
Why do swamp coolers leak more in Arizona?
East Valley water is hard. Minerals build up on the float valve, in the pump and in drain lines, which makes valves stick and lines clog. Long cooling seasons wear pads and pans faster. And because most coolers sit on the roof, a small overflow can run across the roof deck and find its way inside through the cooler's curb or a nearby seam.
Leaks often show up as a stain on the ceiling under the cooler or near the main duct. If you see one, read how to fix a water-damaged ceiling.
Cooler water came through the ceiling? Get the ceiling and insulation dried before the drywall sags.
Call: (856) 481-6893How do you fix a leaking swamp cooler?
- Turn off the cooler and close the valve on its water supply line.
- Remove a side panel and look at the water level. If it is above the overflow, adjust or replace the float valve.
- Check the pan for rust and cracks, especially at the seams.
- Clear the bleed-off and overflow lines.
- Check the supply fitting and tubing for drips.
- Look at the roof curb and flashing around the cooler for gaps.
Working on a roof is risky, especially in the heat. If you are not comfortable on a ladder or roof, call a cooler technician.
Why does my swamp cooler smell musty?
Standing water and old pads grow algae and mildew. Drain and clean the pan, replace the pads, and make sure the bleed-off is working. See what causes a musty smell in your house.
How do you prevent swamp cooler leaks?
- Service the cooler at the start of each season: pads, pump, float and lines.
- Clean mineral scale from the pan and float valve.
- Check the roof curb seal once a year.
- At the end of the season, shut off and drain the supply line and cover the cooler.
- Check the ceiling under the cooler after big monsoon storms.
Swamp coolers are one of several leak sources in Arizona homes. See signs of water damage in walls for the others.