ASHRAE Journal - May 2023 - 8

LETTERS
VRF 101: Managing
Expectations
I am located in Southern
California and a former manufacturer's
representative for two wellknown
variable refrigerant flow
(VRF) manufacturers, a Life Member
ASHRAE and a lawyer. As a result,
I have been exposed to design,
installation, engineering and layout
issues regarding VRF. I would like to
expand on a few points mentioned
in the excellent column by Michael
Gallagher, P.E., Fellow/Life Member
ASHRAE, " The VRF Learning
Curve, " in the January 2023 issue of
ASHRAE Journal.
As-built drawings should be signed
by the contractor and submitted
as a matter of record. The factory
or manufacturer's representative
should be required to review and
approve the " as-builts " and calculate
correct refrigerant charge based on
those drawings. The as-builts should
include distribution boxes and
show their location because making
connections or troubleshooting
the distribution boxes is difficult
without accurate as-built drawings,
which should show condensing
units and access.
Choice of manufacturers: there are
over a dozen VRF manufacturers.
The major players are represented
by local manufacturers' representatives.
VRF layout and specifications
are typically done by the representative
as a service to the engineer or
design build contractor as selections
are based on the manufacturer's
unique computerized selection program.
VRF systems are more complex
than imagined.
Just because condensing unit
size is small (4 tons to 20 tons)
8
and multiple system evaporators
comprise small fan coils or
cassettes, engineers and contractors
underestimate the complexity
of these systems. Choosing
manufacturers should be brandspecific.
The engineer or design
build contractor should choose
well represented brands for their
particular area. Representative
expertise is critical. Factory support,
local factory training, warranty and
parts availability are also all to be
considered. Increasingly, VRF is
being used on larger class A projects
where the owner's expectation on
behalf of their tenants is very high.
If the contractor cannot get field
support or parts like compressors
or circuit boards, the owner is not
going to be happy.
Likewise, choosing a contractor
is most important. If considering
multiple contractors for a project,
the engineer should insist on
meeting the contractors' project
manager and field foreman and
start-up technician. The engineer
should get a list of similar projects,
with information on the equipment
brand, owner's representative and
manufacturer's representative
involved in these projects and
should really check them out.
Owner impressions are particularly
valuable as they represent the
owner's expectation as to equipment
brand, contractor qualifications and
performance, parts availability and
representative support.
It is up to the engineer or design
build contractor to really understand
access required with a VRF
installation. On many projects,
access is not coordinated with the
architect and general contractor. If
the engineer has concerns regarding
ASHRAE JOURNAL ashrae.o rg M AY 2023
access, they should go on record in
writing about their concerns (very
helpful in case of litigation).
Inspection/supervision contracts
between the engineer and architect
or owner are a frequent source of
litigation, as contract language is
often poorly written. If the engineer
is not taking an inspection/supervision
contract, they should notify the
architect in writing, outlining areas
the architect is not responsible for.
If an inspection/supervision contract
is part of the job, the engineer
should specifically define scope and
design areas the engineer is and is
not responsible for.
For instance, would the
mechanical engineer be responsible
for seismic anchorage details, pipe
fastening and support, condensate
pump location and drains and
structural and acoustical issues if
there is no sound consultant on
the project, power and control
wiring, access requirements and
interference with other trades under
an inspection/supervision contract?
VRF installations have many
players, all with differing levels of
expectation, so when push comes to
shove, the engineer is wise to define
and limit their exposure.
There may be situations where
the engineer should use a different
system-where VRF is not easily
understood, will not be maintained,
is in a remote location or where
access is an issue (for instance, in
hotels, condo units or schools).
Perhaps hydronic heat pumps for
condo units or schools and chilled
water/hot water fan coils for hotels,
in lieu of VRF, would be advisable
and less problematic.
VRF is new to North America.
In many cases, it can be a good
http://www.ashrae.org
ASHRAE Journal - May 2023

Table of Contents for the Digital Edition of ASHRAE Journal - May 2023
