ASHRAE Journal - April 2021 - 20

COLUMN SOLVING PROBLEMS

Understanding the Existing System

Del Monaco advises engineers to not solely rely on
the controls vendor to inform them about the existing
system and upgrades, including when trying to prevent
recurring issues in existing BAS.
Engineers need to coordinate with the BAS vendor and
the IT department, said Del Monaco.
When engineers are integrating new components and
controllers into an existing system, they need to know
the terms of licensing agreement, he said. They need to
know what they have with the existing system, and what
they can actually do to ensure the system is cohesive and
functional. Engineers also need to know about the condition of the system, software patches and updates and if
the owner has maintained the system and kept it up-todate, said Del Monaco.
" We need to understand the existing system in detail
and the future needs to appropriately select controllers
and adapt the network, if needed, " he said.
Del Monaco added that another concern with existing
control systems could be dealing with pneumatics. " If
we're upgrading the system from pneumatics to DDC,
there will be physical restrictions in an existing building
that could limit the upgrades due to the financial burden, " he said.

Properly Diagnosing Issues
During the Design Process

To help prevent challenges from arising during
the design process, Benson suggests using industry
guidelines-such as ASHRAE Guideline 36-2018, HighPerformance Sequences of Operation for HVAC Systems. He said
it helped his team working on a campus-wide controls
upgrade project to start with a well-vetted resource (the
Guideline) instead of from scratch.
And, he says, " the more widely these [Guidelines] are
deployed, the better our performance and the more
time our designers, contractors and operations and
maintenance teams can save, " he said.
Bringing those stakeholders together during the design
process is also important. Once the controls contractor
has thoroughly reviewed sequences and has identified
where issues and other methods could be used, Benson
said engineers should schedule deep-dive discussions
about the controls with selected vendors and O&M teams.
" Make sure stakeholders can attend and explore questions and concerns as a group. These sessions require

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an investment of time, but they pay dividends, typically
resulting in better sequences and better-trained staff, "
he said.
Benson said O&M teams often have feedback that
designers do not know. For example, on one project, the
team decided they needed to program the controls system
to start building scheduling earlier than initially planned.
" There is a common sequence, called 'optimized start,'
that starts equipment early (for as little time as possible)
to make sure the air temperature is where it needs to
be by the time a space is occupied. The O&M staff was
adamant: 'We still need to schedule our spaces for at
least half an hour earlier than when people arrive or
they are going to be uncomfortable.' At first we didn't
understand. Why would you do this if you already knew
the temperature would be at setpoint by the time people
arrived? Mathematically, that's right, but we were only
looking at air temperature, and we hadn't taken the
thermal mass of furniture into account. Staff knew this
in their gut, " he said.
After several conversations, the entire project team
figured out the solution to ensure occupant comfort,
Benson said. " One of the lessons that I've learned
through these conversations is to really, really respect
the O&M staff. They have a lot of experience and talents
that our engineers can learn from, " he said.

Field Investigation and Diagnostic Testing

Approaching an issue with a combination of field investigation and diagnostic testing is a strong strategy, said
Kilcoyne. While some BAS manufacturers' software will
provide reports with the quantity, type and protocols of
field controllers on each subnetwork, others do not. This,
he said, then requires engineers to perform physical
inspections to determine these network characteristics.
" On one project in a large government medical center,
we had to perform a hand-over-hand survey of over
six miles [10 km] of communication cable in order to
map out the existing BAS network. Because of infection
control requirements, it all had to be done in mobile
air containment units (MACUs) and took six months to
complete, " said Kilcoyne.
Also, noting the type and gauge of communication and
low voltage power wiring is necessary in field investigations, according to Kilcoyne.
" Frequently, clients request BAS investigations when
they are looking for a plan to update, migrate or replace

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ASHRAE Journal - April 2021

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