How to Prevent Deposits in Evaporative Coolers

An evaporative cooler can help you keep your cool during the hot summer months. Also called swamp coolers, evaporative coolers work best in hot, dry areas. But water in these areas tends to be mineral rich, and the evaporative process leaves behind deposits of calcium and alkaline on the cooler pads and interior of the cooler. The deposits can corrode and rust the metal housing and substantially reduce the operating life of the cooler. Preventing as much of the swamp cooler calcium buildup and other deposits as possible improves cooling, air flow and the life of the cooler.

Close-Up Of Bucket With Soap Water And Sponge
credit: Peter Van Mierlo / EyeEm/EyeEm/GettyImages
How to Prevent Deposits in Evaporative Coolers

Handle Early-Season Swamp Cooler Maintenance

Before you fire up the cooler each year, you'll want to handle a little pre-season maintenance. Begin each cooling season with a thorough cleaning of the evaporative cooler. Remove the cooler panels from the unit. Scrub them thoroughly with a stiff brush and a solution of 1 cup white vinegar to 1 gallon of water. Take special care to clean the panel vanes of all build-up and debris. Paint the appropriate parts, according to label directions, with special paint from a home improvement store. Don't use water in the cooler from a water softener. Because it's sodium rich from the softening process, it can cause scale build-up.

Add Quality Cooler Pads

The cooler pads you choose can make a difference in buildup. Use Aspen cooler pads, and change them as needed throughout the season. Aspen fibers soak up water, conduct it efficiently as a water curtain, and improve the cooling effect. Filters should be changed as often as scale build-up occurs, usually two to three times per season. But you may need to replace them more often if your water is especially high in minerals.

Clean the Unit Regularly

You don't need a special swamp cooler cleaner to spiff up the interior. A simple mix of white vinegar and water is an effective cleaner option. Clean the water pan reservoir in the bottom of the cooler once a month during the season to keep minerals from depositing on the interior. Turn off the cooler, draining the water reservoir pan completely. Scrub it with a stiff brush and the solution of vinegar and water, rinsing thoroughly when you're done. Treat the water reservoir with a chemical scale remover according to package directions to increase the solubility of minerals so they don't stick as easily to the pads.

It's also a good idea to wash the filter and water curtains every two weeks or so. A little mild detergent and lukewarm water does the trick. Clean and rinse the parts well to get rid of any dirt and debris to keep everything working efficiently.

Add a Bleed-Off Valve

Another option is to add a bleed-off valve to the water line that carries water from the reservoir back to the Aspen filters. This valve is available from home improvement stores and is installed on the water line, 6 inches up from the pump connection. It diverts a percentage of the recycled water through plastic tubing to an area of the lawn or garden that can accommodate the mineral rich water, such as Bermuda grass, salt grass or a water run-off.

Shut It Down

At the end of the season, you need to do a little more swamp cooler maintenance. Drain the unit when you're done using it for the season. You'll also want to give it one final cleaning to remove any debris or buildup. If your evaporative cooler has a fan-only mode, run it for about an hour after emptying and cleaning the unit to get everything dry. Use a canvas cover over your evaporative cooler during the winter months. The cover protects the unit and keeps cold drafts from entering the house. Always turn the cooler off at the switch inside the house as well as the switch located at the top if the unit, on the underside of the top cover.

Swamp cooler maintenance helps to minimize the buildup of minerals that can make your unit run less efficiently. The little time you spend on maintenance can extend the life of your swamp cooler.