San Francisco Restaurant Solves
Cooking Hood Draft Challenges with Fabric HVAC Diffuser
diffuser reverses dining area cooking odor infiltration,
reduces sanitation costs, improves employee air comfort and
reduces energy costs.
Danville, Calif.--Facing seemingly insolvable performance
challenges from its kitchen ventilation system, Bridges
Restaurant & Bar, Danville, Calif. was ready to outlay
upwards of $20,000 for a new rooftop make-up air system.
of exiting through the dual exhaust cooking hood, smoke and
food odors wafted into portions of the 3,300-square-foot
dining area raising complaints from patrons seated at tables
near the kitchen.
The 24-year-old, independently-owned Bridges is popularly
known in the San Francisco area for its casual-elegant
dining and also as the famous location for actor Robin
Williams' comedic multiple costume changes in the 1993
Hollywood movie, "Mrs. Doubtfire." Because of its upscale
image and popularity, the vexing dining area cooking odors
were bad for business and affected the overall guest
experience, according to Kevin Gin, executive chef and a
member of the restaurant's investor consortium.
Furthermore, drafts from the existing make-up air HVAC
system were drawing smoke and grease, that should have been
contained within the cooking exhaust hood, and depositing
them onto the diffuser, walls ceilings and other kitchen
surfaces requiring more than $1,000 annually in maintenance
labor and cleaning compounds.
Besides odor infiltration and maintenance costs, the drafts
from the air conditioning supply over the food prep area was
prematurely cooling prepared hot entrees while employees in
other kitchen areas were uncomfortably hot.
Finding a Low Cost Solution
A large HVAC retrofit outlay seemed imminent until an
arranged meeting between Gin and an HVAC ventilation product
manger attending a Bridges-held 25th anniversary dinner for
the nearby Food Service Technology Center (FSTC), a San
Ramon, Calif.-based commercial foodservice equipment
performance test lab funded by Pacific Gas & Electric. Nick
Paschke, product manager at textile HVAC ductwork
manufacturer, DuctSox Corp., Peosta, Iowa, recommended a
custom textile air dispersion system designed specifically
for kitchens. The ceiling-mounted device disperses airflow
uniformly, parallel and in front of the kitchen exhaust
hood. The fabric diffuser is an easy-to-install replacement
for metal air distribution diffusers that commonly cause
kitchen exhaust hood overflow.
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of a 5,000-cfm make-up air equipment replacement, only the
kitchen's lone conventional 3 x 3-foot supply box and four metal
diffusers were switched out. Located over the food prep line to
distribute air throughout the 1,000-square-foot kitchen, the
diffusers were replaced with two eight-foot-long,
28-inch-diameter D-shaped KitchenSox® fabric diffusers. Instead
of the metal diffuser's estimated 500-fpm airflow that caused
turbulence and disruption of the cooking hood's capture, the air
is gently and evenly dispersed through the fabric into the
entire kitchen area at a significantly slower 85-fpm rate.
Without the previous high velocity airflow and subsequent
turbulence, the dual exhaust cooking hood now efficiently
performs up to its design standards and captures smoke, grease
particulates and cooking odors without overflow.
CulinAire Systems, El Dorado Hills, Calif., a foodservice
ventilation contractor specializing in demand ventilation
controls and engineered kitchen ventilation equipment,
fabricated the sheet metal plenum and metal/fabric adaptors that
supply the 16 linear feet of fabric duct. The fabric duct system
and metal accessories were installed by CulinAire overnight
without disruption to the kitchen operation.
Without the drafts, the excessive airborne smoke, grease
deposits and dirt that the return air system had once drawn onto
diffusers, kitchen walls, ceilings and cabinets no longer
occurs, which has expedited daily cleaning and sanitation
Gin also plans annual cleaning since the fabric diffuser can be
disassembled by kitchen staffers in just minutes and
commercially laundered, a process that would require days to
complete by an outside contractor with a metal system.
Green Mission Accomplished
By improving the air distribution and eliminating the hood's hot
air overflow into the kitchen, a considerable energy savings
supplements Bridges' green mission, which is strategically
marketed among its clientele. Gin said it's difficult to
pinpoint energy savings of the new system because FSTC
continually uses Bridges as a beta test site for new technology.
However, Gin did estimate recent Bridges' conservation efforts
are saving the restaurant more than 20-percent in energy costs
with quick investment paybacks.
For example, FSTC oversees results of Bridges' variable speed
Intelli-Hood control, which is manufactured by Melink Corp.,
Milford, Ohio, and won the renowned "AHR Innovation Award" in
the ventilation category presented at the 2012 AHR Expo in
Other green equipment includes:
· A Cyclone Xi 96-percent efficient hot water heater by A.O.
Smith, Ashland City, Tenn.;
· A variable temperature control for more efficiently running
walk-in cooler operation by E-Control Systems, Sherman Oaks,
· High temperature/reduced water kitchen and bar dishwashers by
Hobart Corp., Troy, Ohio;
· A lighting retrofit from standard bulbs to compact
· The highest efficiency equipment available today in fryers,
convection ovens and ice machines by Vulcan-Hart Co., Baltimore,
Md.; the Garland Group, Freeland, Pa.; and Manitowoc Ice Inc.,
Manitowoc, Wis.; respectively.
Bridges' challenges with HVAC ventilation was solved completely
with fabric diffusers that cost less than ten percent of the
approximate $20,000 for a new make-up air system. Furthermore,
the energy savings and reduced maintenance costs offer a payback
of less than one year on the air diffusion system. "This is
really a common problem (inadequate cooking hood drafting) I
think many restaurants suffer from and don't realize there's a
simple, inexpensive solution," said Gin. "We once thought
replacing the HVAC system would improve our kitchen ventilation
challenges, but we now realize it probably wouldn't have
remedied what was actually a ventilation problem that fabric