FloAire Canopy Hood - Manual (Page 33)

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Performance Evaluation
A performance evaluation of the system can be performed only after all of the following items have been
verified:
1. All fans are operational and rotations visually verified by observation of the arrows stamped on
them.
2. All filters are in place.
3. Equipment under the hood is in place and operational.
4. HVAC units are in place and operational with blowers operating correctly.
Guidelines before Beginning
The testing and balancing of a system is necessary to ensure proper and efficient operation of the system
as it was designed. In any building where effluent and hot air is removed, the mass of air must be
replaced to maintain a constant pressure in the space. Any change in the pressure differential between
inside and outside air will in some way affect the operation of a system; most commonly that affect is a
negative one.
A test and balance, as well as the simple performance test in International Mechanical Code Section
507.16.1 should be included in all jobs; code inspectors are increasingly enforcing these requirements.
Requirements in the 2006 IMC, which is currently effective in most parts of the United States, are as
follows:
“507.16 Performance test. A performance test shall be conducted upon completion and before
final approval of the installation of a ventilation system serving commercial cooking appliances.
The test shall verify the rate of exhaust airflow required by Section 507.13, makeup airflow
required by Section 508, and proper operation as specified in this chapter. The permit holder shall
furnish the necessary test equipment and devices required to perform the tests.
507.16.1 Capture and containment test. The permit holder shall verify capture and containment
performance of the exhaust system. This field test shall be conducted with all appliances under
the hood at operating temperatures, with all sources of outdoor air providing makeup air for the
hood operating and with all sources of recirculated air providing conditioning for the space in
which the hood is operating. Capture and containment shall be verified visually by observing
smoke or steam produced by actual or simulated cooking, such as with smoke candles, smoke
puffers, etc.”
The simplest means of doing the performance test is using a T-T puffer from
www.evhill.com . Activate the
puffer and use it to trace effluent around the entire perimeter of the hood, emitting smoke every few
inches under the lower edges of the hood.
External Factors which may affect Hood Performance
1. HVAC units are generally specified to supply 25% outside air (OA) to the room ventilation. If
RTU’s are not supplying the proper amount of OA to the building, then negative pressure will
exist.
2. HVAC return grilles located close to a hood can cause performance problems. The return grille
competes with the hood to capture air in the room. For example, a return grille for a 10-ton HVAC
unit can draw anywhere from 3000 to 4000 CFM. This is equivalent to the exhaust of a 10’ to 13’
canopy hood. As a result, a return air grille located within six feet (6’) of the hood can have a
serious effect on the capture ability of the hood.
3. HVAC diffusers located near a hood can create flows in the room that detract from the capture
ability of the hood. If the HVAC diffuser bounces air off the front of the hood or directs air along
the hood and past the end, the air flow created can draw smoke and contaminants out of the
hood.