Rick Sewell is the engineering manager for Crawford Broadcasting’s Chicago cluster. Each year, cottonwood trees fill the air with their cottony seeds. They fill the air conditioning coils at his sites, too.
Those sites include studio/office buildings and four transmitter locations — nearly 25 outdoor condensers to clean.
You may be familiar with self-contained Eubank air conditioning systems that are often seen hanging on the side of pre-fab buildings at cell sites. The coils of these Eubank systems are notorious for being difficult to clean.
Rick’s Burnham site has five such systems in use at the transmitter and flywheel UPS buildings. The coils are hard to get at via hose cleaning. Worse, the site sits next to a swamp in a forest preserve. Not only does Rick have to worry about an onslaught of the cottonwood seeds, but water-loving weeds grow all around the site tall enough to hide Bigfoot; and the weeds just happen to bear flowers that end their own lives as air-blown seeds.
The result is an entire growing season of stuff in the coils of the AC units. Rick cleans the coils, but two weeks later they look like they have been neglected for years. Cleaning becomes a regular summer time chore.
Playing with a fire hose every couple of weeks isn’t the least pleasant task for an engineer, but Rick had had enough after two summers of dealing with this problem. He began to think there had to be a better way.
He decided to take a different approach. Rather than a new cleaning technique, he sought to keep the coils clean in the first place.
Fig. 1: Here’s the Eubank air conditioner with air intake grate visible.Fig. 2: This “pre-screen” is held in place with magnets. Seedling fluffies will be trapped. Rick knew that the Eubanks units have rather small openings on their side to allow air to flow into the coils. As you can see in Fig. 1, there is not much of a filtering grate in place to stop anything but large items from getting into the coils.
Rick had planned to install some sort of pre-screen to catch all the fluffy stuff before it got into the coils. This would still allow air flow across the coils. He decided to purchase the materials to build his own screens and place them over the openings on the units’ sides.
This project was going to involve building the screens and figuring out how to hold them in place. But it dawned on Rick that he knew of an existing product that would work perfectly. It was also inexpensive, which is always a plus.
The adjustable screens, shown in Fig. 2, would be perfect for the job. He just needed to find the right height that would translate to the width of the Eubank opening, then adjust the length for the height of the opening. At the Burnham site, the 10-inch by 37-inch size was nearly perfect.
Rick then used two powerful magnets to hold the screens in place. More magnets might be necessary during high-wind events.
Now Rick has something that will keep those nasty fluffies out and will be easy to maintain and keep clean. If you adopt this tip, be sure to check and clean the screens regularly or you’ll just end up with clogged screens instead of clogged coils.
In Rick’s case, the site is only a few miles from the studio; he can travel there at least once a week. It may be that Rick finds that during the worst part of the season he’ll need to check and clean the pre-screens twice a week. He is still trying to figure out how quickly the pre-filters will get clogged, but it’s well worth a trial run.
Tips to Workbench help your fellow engineers and qualify for SBE recertification credit. Send your good ideas to firstname.lastname@example.org. Fax to (603) 472-4944.
Author John Bisset has spent 46 years in the broadcasting industry. He handles West Coast sales for the Telos Alliance, is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.