CEAC-2021-02-February

CHILLER REPLACEMENT AT
645NORTH MICHIGAN AVENUE
By Karl J. Paloucek
There’s a phrase that comes up from time to time that says,
“Little things mean a lot.” Usually it’s a gauge of sentiment.
But sometimes, in the world of building systems
management, finding something little can mean that big changes
are in store. When Tim Clarke and his fellow engineer, James
Domina, found they had a leak in the evaporator tube in one of
their centrifugal chiller units at 645 N. Michigan Ave., they knew
right away that they had to patch it. But they also knew that
that leak was telling them something: It was going to be time to
replace this aging chiller.
and Moriarty made the decision to contact Air Comfort about
implementing a modular chiller solution that would satisfy
the building’s needs without requiring a major remodel. What
they decided on was the installation of six Carrier AquaSnap®
30MPW units to replace the centrifugal, offering redundancy as
well as a greater latitude of control. ASHRAE 90.1-compliant,
quiet and easy to use, the 30MPWs offer 71 tons per unit for a
total capacity of 426 tons. With two compressors per unit, that’s
35 ½ tons per compressor. And, of course, the benefit of redundancy.
“We had a power winch, and elbow
grease for the rest of it.”
-James Domina, Engineer
“We were like, ‘It’s not going to last that long with the patch,’ so
we pretty much got the ball rolling from there on what we could
do,” Domina recalls.
The existing pair of chillers had been installed at the time of
construction. They were enormous, and walled into their own
separate rooms. Looking at the logical point of entry for a new
centrifugal to be brought in — a standard doorway — it was
clear that replacement with the same scale of technology was
going to require a massive remodel with walls being moved, and
likely considerable disruption of building operations. They were
looking at a costly road ahead of them, and it didn’t suit. “That’s
when [we] started to realize to go into a mod, or smaller chillers,
to go that route, which, I think, was ultimately the better route,
even versus a centrifugal chiller.”
Clarke, the chief engineer at 645 N. Michigan Ave., and Charlie
Moriarty, the property manager, discussed the pros and cons,
Air Comfort Sales Engineer Scott Leitner says that the property
was already in great shape to make the change. “A year prior to
this, the building ended up putting in a brand-new VAS control
system for all of the mechanicals in the building and everything,
so that was done,” he says. And because the chillers are equipped
with BacNet controls, that allowed them to be tied directly into
the building automated control system. “With this project, this
system was tied into the new control system they have, so now
everything is on the upgraded VAS.”
But before any installation could happen, the first things that
had to be contended with were the logistics of removing the
centrifugal and making room for the new. And that was not
a small job. DAY Scrap Metal came to do the heavy lifting. “It
was all enclosed,” Leitner says. “The room had to come down —
not just demo, but electrical and so forth, so it was a pretty big
undertaking.”
(Continued on pg. 40)
Volume 86 · Number 2 | 39