Application Note

2 Fluke Corporation Standardizing on clamp meters for HVAC service
Picking a meter
MacDonald-Miller didn’t choose
the 902 on a whim. They did
their research, looking for a utili-
tarian meter that would make
the measurements needed, that
would be reliable (“these guys
trust the meters with their lives,”
says Sundby), that would handle
the day-to-day banging around
common to field maintenance,
and that would handle the envi-
ronment. While not the deciding
factor, cost was important as
well, considering the number of
meters involved.
All in a day’s work
While it would be difficult to
define a typical day for Sundby’s
crew—“Nothing is ever really
typical, because we’re so well
versed,” he explains—a typi-
cal job with rotating equipment
involves using the 902 to do
voltage and current tests, and
phase imbalances in both volt-
age and current. Measurements
on the rest of an HVAC system
include temperatures on pres-
sure, suction, discharge and
liquid refrigerant lines. “We do
delta Ts across the evaporator
coils and across the condenser
coils, and we check suction tem-
perature, discharge and liquid
temperatures,” Sundby explains.
“We use the 902 for that, too,
because it’s our all-in one; they
just switch a lead and they can
change to their temperature and
they got surface probes they use
and off they go.”
Knowledge is power
The regularity of maintenance
work is the source of much of
its effectiveness. As technicians
work on motors, says Sundby,
they make records of the reading
they take and enter them into a
database for predictive mainte-
nance purposes. “We try to trend
it, we try to keep a running log
on what equipment looks like,
and if we start seeing failures
we’re trying to predict failures,”
he explains.
They would like to implement
a full asset management system
that would collect equipment
history and also connect to the
accounting software and con-
struction departments, and have
been working at it for several
years. There’s still a ways to go
to gaining that edge, but predic-
tive maintenance goes on all the
same. “For the most part the guys
are consistent on their work-
load,” he explains. “They kind of
remember and they know what’s
been going on; they start watch-
ing for that trend of motors going
downhill and that type of thing.”
Good work takes training
Maintenance work on com-
mercial and industrial HVAC
equipment is not a trivial task,
and making sure the people
who do it are up to the task
involves more than just provid-
ing them with the proper test
instruments. Most newly-hired
technicians are graduates of
a two-year associate’s degree
program at a community college
or tech school, Sundby explains.
When they’re hired by Mac-
Donald-Miller or another union
contractor they enter a union
apprenticeship program that lasts
for four years—or five, for those
who don’t have that associate’s
degree. And even after six years
the training doesn’t stop. The
company maintains a large train-
ing facility in Seattle. “We put
on three-hour classes twice a
week.” says Sundby. “The guys
come in at night and get fed and
get to learn about new products
and testing and programming,
whatever it happens to be,” from
refrigeration to safety. In addi-
tion, suppliers conduct classes on
everything from meters to vari-
able frequency drives.
You’d think that union wages,
a solid company and a job that
can’t be outsourced overseas
would attract lots of applicants,
but Sundby reports that it’s get-
ting more and more difficult to
find qualified people. He’d like
to see more encouragement for
young people to consider alter-
natives to a four-year college
program. As he says, “not every-
body’s going to be happy with a
desk job.”
After all, Sundby says, part of
what’s made this country great
“is manpower, and labor, and
quality work.”
Liquid line temperature measurements for subcooling.