Figure 2. Armstrong Vertical Pump (Series 4300).
What’s your angle?
Steve Tredinnick, PE, Vice President of Energy Services, Syska Hennessy Group
Courtesy Armstrong Pumps.
Editor’s Note: “Inside Insights” is a
column designed to address ongoing
issues of interest to building owners,
managers and operating engineers who
use district energy services.
Recently I came across what I think to be one of the engineering world’s perennial dilemmas. You know, the
type of quandaries along the lines of,
What came first, the chicken or the egg?
Dark ale or light beer? Tastes great or less
filling? Apple pie or pumpkin pie? Vikings
or Packers? Or the perpetual argument in
our household, Do nuts really belong in
My engineering dilemma reference is,
What angle do you prefer – horizontal or
vertical? And no, I‘m not playing an angle
here. I am specifically referring to pumps.
Just like brownies and pies, pumps
come in several flavors and colors, as well
as different orientations with respect to a
horizontal or vertical axis. Horizontally oriented pumps are parallel to the horizontal
axis and usually are supported on an isolation base; vertically oriented pumps are
parallel to the vertical axis and typically
supported by piping, or the pump casing
may extend to the floor, depending on the
In recent years, I have seen both configurations installed at central plants that I
have had the opportunity to visit – either
for project-related reasons or as part of the
great tours provided by IDEA during conferences. From these visits, I get the
impression that there is a clandestine
movement by engineers or contractors to
use the vertical configuration for distribution pumps.
Figure 1. Bell & Gossett Horizontal Pump (VSC).
installation costs, floor space and maintenance. Those advantages sound great, but
do they apply everywhere? As you may
surmise, I am pessimistic about that. For
some reason, vertical pump configurations
just seem to bug me – they seem like
somebody wimped out when fighting for
space. It’s a bit like putting ketchup on a
chili dog: It just doesn’t seem right. However,
the pumping industry obviously felt there
was a need for vertical configurations,
since it seems to be filling that gap. So
what is the big deal? Let’s look at the pros
and cons of a large vertical distribution
pump, outlined in table 1.
Courtesy Bell & Gossett.
To further illustrate my viewpoint: We
recently had a project to replace four existing chilled-water distribution pumps with
three larger ones. The new pumps are
10,000 gpm and 400 HP each. We selected
both horizontal and vertical pumps and
then laid them out in the available space
Since I have never used the vertical
in-line for large distribution pumps, I have
often wondered, What am I missing on
this issue? Hence, I decided it was time to
do some research and get smarter on the
subject. If you need a refresher course or
an illustration for these pumps, please
refer to figure 1 for a typical double-suction horizontal pump and figure 2 for a
double-suction vertical pump.
In general, the published literature for
the vertical pumps claims many advantages
over traditional horizontal split case-type
pumps, including savings in the areas of
Figure 3. Pump Room Layout Using Three
Courtesy Syska Hennessy Group.