ASHRAE Research Project 1480 Report - Food Service Technology ...

Evaluation of Hood Overhang Dimension
Hood capture and containment performance relative to the front and side overhang of the
appliance line was investigated using heavy-duty gas broilers at simulated cooking conditions. In
all cases, increased hood overhang resulted in decreased exhaust airflow required for capture and
containment of the effluent plume.
Front Overhang
For front overhang evaluation, three broilers were used, with the left and right overhang
dimension maintained at 6.0 inches to the appliance cabinet. The results are shown in Figure 27
and discussed below.
10000
Exhaust Airflow Rate [cfm]
8000
6000
7400
8600
8000
4000
2000
0
Front Overhang: 12.5"
Rear Overhang: 12.5"
Centered Front-to-Rear
101
Front Overhang: 6.0"
Rear Overhang: 20.3"
Min Front Overhang
104
Front Overhang: 20.3"
Rear Overhang: 6.0"
Min Rear Overhang
105
Figure 27. Evaluation of Hood Front Overhang
When front overhang was evaluated with the three broilers at simulated cooking conditions,
operation with the appliance cook surfaces centered under the hood was optimal. At this position,
which provided a front and rear overhang of 12.5 inches, relative to the cooking surface, the
required exhaust rate was 7,400 cfm (740 cfm/ft). Note that relative to the appliance cabinet, the
front overhang was 4.5 inches and the rear overhang was 10.1 inches. With the appliance pulled
forward to a 6.0-inch front overhang and 20.3-inch rear overhang relative to the cook surface,
8,600 cfm (860 cfm/ft) was required. With the appliance pushed back to a 6.0-inch rear overhang
and 20.3-inch front overhang relative to the cook surface, 8,000 cfm (800 cfm/ft) was required.
3-3
RP-1480