All hood filtering, whether meshes, baffles, or VAH sling designs, can only remove part of the grease aerosol particle spectrum. This part is that of the larger diameter particles, with decreasing performance through the mid-range. The rest is hoped to be discharged into the atmosphere, but there will be some collection in ducting depending on various factors. The only system I know of that can handle the entire spectrum is the intense UV approach used above commercial perforated ceiling collection designs. Hence, discharge into an attic not only subjects the attic to grease, water vapor, and odor, but could potentially be a fire hazard. Is there a reference somewhere in which VAH specifies that attic discharge is allowed? Earlier, the value 90 was raised. That may have been a misapplication of my expressed opinion on the flow rate (cfm) desirable per square foot of hood aperture to ensure that the 3 ft/s rising effluent from hot sources (griddles, woks, etc) is assured of containment by baffles and meshes. Rules of thumb such as cfm per BTU/hr or cfm per foot of hood edge are derived from various assumptions about the nature of the cooking field. kas

Measurements made with commercial cooktops using "side panels" along with a hood that was the same width as the cooktop revealed that the side panels were effective in keeping the plumes headed toward the hood aperture, even when a salamander was mounted on the back wall near the panel. Examples of these side panels on commercial units may be seen in the attached figure. Cabinets on each side of the cooktop can perform similarly, but less effectively due to not usually being deep enough, front-to-back. This will depend on whether the front or back burner is being evaluated. Of course, cabinet placement and size must conform to appliance manufacturer requirements for distances to inflammable materials. From: CKV_Design_Guide_2_031504.pdf by the California Energy Commission Side Panels and Overhang Side (or end) panels (as represented in Figure 12) permit a reduced exhaust rate in most cases, as they direct the replacement airflow to the front of the equip-ment. They are a relatively inexpensive way to improve capture and containment and reduce the total exhaust rate. In fact, one of the greatest benefits of end panels is to mitigate the negative effect of cross drafts. It is important to know that partial side panels can provide almost the same benefit as full panels.Bottom line: Don't panic if your cabinets preclude the hood width that would be otherwise desirable. You might consider a partial panel with your hood to augment the cabinets. The panel partially obscured by the cabinet shouldn't look too obtrusive.

We have a DCS 48" dual fuel range with 5 burners and a griddle and it was installed in about 2008. It has worked very well. The only odd part about it is that the electric ovens do not have a timer, clock or other features that are typical of less expensive ranges. Its made more like a commercial range than a home unit, but is rated for a home installation with surrounding cabinets. Maybe the newer ones have added those features. We used a custom-made surround/chase above the range, and a Vent-a-Hood insert with a triple blower system that I believe is rated at 900 cfm. It required a 10" duct, IIRC. Based on the vent-a-hood site info, for a 30" range you should have a 36" hood (3" overhang on each side), and they do offer a 600 CFM fan option. Bruce

The glowbar igniters are a really old and proven technology. You'll find it in lots of gas appliances (e.g. water heater, furnace, ovens, ...) as they are so safe. Whenever the thermostat calls for heat, it turns on the igniter. As a first approximation, a glowbar igniter is the same thing as an incandescent light bulb without the protective glass shell. It draws a couple of hundred watts and uses that to produce heat. Right next to the glowbar is a temperature activated gas valve. As long as no heat it produced (i.e. glowbar doesn't call for heat or glowbar is defective), no gas flows. This is very safe. But if the valve detects sufficient amounts of heat, it opens and gas flows over the glowbar and ignites. This is damn simple and there is very little that can fail catastrophically. So, it is inherently a safer design than using click igniters. Those are good for the stove top where a person can supervise the burners. But the oven has to work even when it cycles on/off without human intervention. The downside, of course, is that this glowbar behaves just like an incandescent bulb. Some bulbs live for decades, most live for a couple of years, and a small number dies within months. Same is true for glowbars. Nothing much you can do about it. Fortunately, they are cheap and standardized components. Every appliance manufacturer buys from the same factory. And yes, gas ovens always cycle on/off completely. There generally isn't a great way to modulate heat output. This is a noteworthy difference when compared to electric ovens, which frequently can keep constant temperatures much more easily. For many dishes, that doesn't actually matter. But there are some that do in fact cook much better in an electric oven. And I guess the reverse is true too.