CINCINNATI - A new tool for gas furnace troubleshooting, named
the “Draft Simulator,” has been developed to serve as a reliable way to test
pressure switches, ensuring they open and close at their manufactured ratings.
The invention is also used in finding a switch with a bad or weak diaphragm and
in verifying switch consistency.
The handheld tool was invented by Richard McFarland, an HVAC service
technician since 1975. It weighs 13.7 ounces with its battery inside, and
measures 6.5 inches long, 3-5/8 inches wide, and 1-3/8 inches thick. Its light weight
and handheld size provide for portability and ease of use in the field.
According to McFarland, the Draft Simulator works by connecting
to a manometer and the pressure switch using small rubber tubing. After the
leads are connected to the pressure switch, a knob at the top can be turned to
adjust suction to the pressure switch which, in turn, simulates the behavior of
the draft inducer. Without the furnace running, technicians are capable of
verifying the operation of any pressure switch.
An unnoticed faulty switch may result in undesired service
warranty visits, lost potential income, and additional time spent diagnosing
intermittent failures, noted McFarland. “You spend hours and even replace good
parts, until finally, you catch it in the act and it was the pressure switch
all along,” he said.
Commenting on the Draft Simulator, William Potts, president of
Potts Heating & Air Conditioning, said, “It has reduced call backs, and
improved our cost of doing business; it even allowed us to earn customers
because other companies couldn’t figure out what was going on.”
The Draft Simulator is under U.S. Patent No. 7,441,439 B2. For
more information, visit www.pressureswitchtester.com.
Publication date:08/09/2010
