The chilled water HVAC system at this Cleveland office building worked well under normal operating conditions. However, a couple times a year, gnat-like bugs called mayflies caused havoc on its HVAC systems, resulting in significant maintenance efforts. Installation of self-cleaning stainless steel filters zapped the bug problem.


Facilities personnel are regularly called upon to debug problems in their HVAC systems. In some cases, the thermostats need resetting. Sometimes the registers need to be adjusted. At North Point, a two-building, 800,000-sq-ft office complex in Cleveland, this meant removing the mayflies that were clogging the A/C units.

“We get mayflies a couple times a year and they would plug up the strainers on all the floors,” said maintenance engineer Brad Schindler. “We would have to go running around cleaning strainers because all the A/C units would be going down.”

But all that changed when North Point installed a self-cleaning Tekleen filter from Automatic Filters, Inc., eliminating the emergency calls from tenants.

Airborne Assault On The A/C

The North Point office complex consists of two buildings on Lakeside Avenue in downtown Cleveland, walking distance from Lake Erie, the Rock and Roll Hall of Fame, and Cleveland Browns Stadium. The first one built was the North Point Office Building, or North Point I, a 242,000-sq-ft, seven-story, irregularly shaped building featuring triangular floor plans. North Point I opened in 1985, and was joined five years later by the North Point Tower (North Point II), a 20-story, 587,000-sq-ft building. Joining the two is a covered pedestrian bridge. Both buildings provide tenants such as the HMO Kaiser Permanente and consulting firm Watson Wyatt with an unobstructed view of Cleveland’s inner harbor and the lake beyond.

To provide heating and A/C for the tenants, the North Point buildings use a Trane cooling tower to deliver chilled water. Three pumps (one on standby) send the water to the compressor units inside the tower. Each floor has two Trane 60-ton units. At times, the water piped from the tower is enough, but each floor unit also has three compressors that are staged to provide additional cooling as the weather demands.

The water system worked well under normal operating conditions, however, a couple times a year the mayflies would hit. These same mayflies garnered national attention this past fall when they swarmed the field at Jacobs Field when the Cleveland Indians played the New York Yankees in the American League Divisional Series. And while in that case they were drawn to the bright lights, they also wreak havoc on HVAC systems.

“They mob the place,” said Schindler. “We get piles and piles of them.”

While the janitors would take care of the dead bugs lying around the property, the engineering crew had to deal with all those who opted for a watery grave: getting inside the cooling tower, into the piping, and finally clogging the compressor unit strainers. Each unit would only take about 10 to 15 min to clean out, but when you have 40 units on 20 floors, that time adds up. More significant was the way they interrupted the schedule.

“The big problem is that it was usually an emergency,” said Schindler. “When units start going down, we have to drop everything and go clean them out to keep the units running. The idea is to keep the tenants happy.”

Getting The Bugs Out

To eliminate all the emergency calls, the facilities team decided to install self-cleaning Tekleen filters from Automatic Filters, Inc.

“We liked that the filter cleans itself so we don’t have to do anything,” said Schindler.

The Tekleen filters incorporate a unique self-cleaning mechanism that allows an uninterrupted flow of filtered water even while the cleaning takes place and uses a fraction of the water that normal back-flushing requires. Tekleen filters also use stainless steel as the standard screen material, rather than a special order option, resulting in a longer-lasting filter.

North Point staff selected the Tekleen ABW14-P filter, which as a 316L stainless steel body and a stainless steel filter with 16-mil holes. The unit has 10-in. inlet and outlet flanges and a 2-in. flush valve. It was designed to filter 3,000 gpm from the cooling tower’s two 1,500-gpm pumps. With it in place, the maintenance crew no longer gets emergency calls from tenants complaining about their A/C being down. They do still check the strainers when doing routine preventive maintenance, but there is very little found in them. ES