After 37 years and dozens of burned-out compressor replacements in the refrigeration service business, Paul Getejanc thought he had seen everything until he peered into the line sets of a recently burned-out 35-ton split-system air conditioning rooftop unit.
“It was the worst burn-out I’ve ever seen. The 2-1/8-inch suction line looked more like a sooty smoke pipe,” recalled Getejanc, the owner and operator of North Macomb Mechanical of Washington, Mich., who is also a deputy director of Detroit Chapter-Refrigeration Service Engineers Society (RSES) and the seven-year education chairman of the RSES’ Michigan State Association.
The seemingly hopeless situation raised the question as to whether a severely burned-out unit with an expensive replacement value is salvageable.
Most service techs would pronounce the unit dead and even Getejanc was skeptical as to if he could clean the thick sludge throughout the system composed of acid, moisture, and debris from fried compressor motor windings.
JUMPER CABLE TROUBLEThe burnout was no fault of the seven-year-old unit. During the Warren, Mich., industrial building’s total remodeling, a refrigeration service company had evacuated the fully functional unit … but only partially. Looking for a cooler work atmosphere inside the building, remodelers later overrode the unit’s automatic cut-off switch with contactor jumper cables and attempted to run the unit even though it was approximately 40 pounds low on refrigerant. After the remodeling, Getejanc was called for the unit’s start-up. He found the jumper cables still in place, fried contactors, and one very large mess inside the unit and line sets.
OLD DAYS, NOT TODAYIn the old days, Getejanc would use R-11, but the outlawing of it as a refrigerant as well as a line set cleaner sent him searching for a replacement.
Getejanc and his two assistants started the refurbishing attempt by flushing the 40-foot-long line sets - which were impractical to replace - with a biodegradable, environmentally safe flush (Qwik-System Flush from Mainstream Engineering).
After recovering the remaining 27 pounds of the 65 pounds of R-22 originally in the unit, Getejanc disconnected the line sets, crimped the ends to create pressure during flushing, and performed a pre-flush procedure of blowing out loose debris with 150-psi of nitrogen. Getejanc then injected the flushing agent with a conically shaped “one-size-fits-all” adaptor he pushed into the line sets.
Getejanc used five 2-pound aerosolized cans of the flush on the open-ended line sets, condenser, and evaporator coils followed again by nitrogen purges. During the flush and purge processes, Getejanc also installed various in-line filter/driers to catch debris.
The condenser received a nitrogen and flush treatment. However it was only mildly contaminated, he said. The evaporator coil however was challenging because it had a header that could possibly harbor contaminants. Getejanc drilled a 3/8-hole in the header and brazed in a small valve/cap set-up to help oscillate out any contaminants. Later on, the hole was brazed.
The flush process took about four hours. The entire retrofit took three days. About a year after the project, Getejanc was checking pressures and routinely changing the air filters. He said the unit has never had to have a subsequent repair since the clean up and it was running up to specifications.
For more information, visit www.mainstream-engr.com.
Publication date: 05/11/2009