Besides removing odors, best units get rid of moisture -- quietly
Friday, November 02, 2007By Paul BianchinaInman News
In most kitchens, there is a simple appliance situated above your range or cooktop that often seems to be mistaken for nothing more than a big light fixture -- and in fact, the "builder's grade" range hood in many new homes really is little more than that. But your range hood serves a couple of very important purposes in the kitchen, and selecting the right one is something that warrants some comparison shopping.
Range hoods come in several sizes, finishes and designs, and that's where most people start when they're shopping for a new one. First of all, it needs to be the correct size to match the width of the opening in the cabinets above the range, and to match the width of the range or cooktop itself. Hoods come in a couple of standard sizes, including 30, 36 and 42 inches in width, with the depth being designed to fit with standard 12-inch-deep upper cabinets. There are some variations available in many of the higher-end models, so knowing the size you're looking for is the first step.
Typically, the next consideration is one of aesthetics. There are several finishes available, the most common being white, almond, black, stainless steel or some combinations of those colors. Then there's the design of the hood housing, which can range from the traditional rectangular box with the sloping front that is commonly see in kitchens of all types, to some very sleek, slender models that almost disappear into the cabinets.
AN EXHAUSTING CONSIDERATION
Size and aesthetics aside, it's time to take a look at what really makes the range hood function in the capacity that it's designed for -- exhausting air. Range hoods utilize a fan to draw air up and into them, through a filter, then through a duct to -- hopefully -- the outside. That air movement serves to remove cooking odors from the kitchen, and that's when most people will turn it on.
But the range hood has an even more important and often overlooked role as well, which is to remove moisture right at the source where it's being generated. Like a bathroom fan, the range hood lives to draw warm, moisture-laden air out of the home's interior and exhaust it to the outdoors before it can do any harm. For that reason, there are three additional things to pay very close attention to when buying and installing a range hood.
First of all, since the hood needs to remove moisture from the room, you want to avoid the temptation of purchasing a recirculating hood. Recirculating hoods do not require an exhaust duct, so they are considerably cheaper and easier to install. But since all they do is recirculate air through a filter to remove some of the grease and odor, they fail completely in their primary task of removing moisture.
Second, the hood has to be vented all the way to the outside. This is now a building code requirement in today's homes, but in years past range-hood ducts were often run into the attic and no further. As many homeowners have found to their shock and dismay, pumping all that warm, wet air up into the attic can cause a whole host of problems, including dryrot, mold, degraded insulation, and even severe structural damage.
Finally, the range hood needs to have adequate power to effectively remove the air. As with all types of ventilation fans, range hoods are rated in cubic feet per minute (CFM) of air movement. The higher the CFM rating, the more effective the fan is at drawing in room air and pushing through the duct. Larger rooms and larger ranges need more CFM to more an adequate amount of air for ventilation, but even small rooms need a greater amount of CFM if the exhaust air needs to be pushed though a long run of duct, or one with a large number of elbows and other fittings.
At their least expensive, hoods utilize a tiny plastic rotary fan on a vertical shaft, sort of like the propeller on an old beanie cap. Even though a massive 42-inch hood looks powerful enough to handle any ventilation chore, if it's equipped with an anemic motor and fan blade, the resulting air movement will be inadequate.
Better range hoods utilize a multifinned horizontal fan called a centrifugal fan, commonly known as a squirrel cage fan for its resemblance to a common animal exercise wheel. Centrifugal fans are much more efficient at moving air, and offer a higher CFM then a rotary fan with the same size motor.
The final consideration with your new range hood is its noise level, because even the best of hoods won't get used if it sounds like a Boeing 747 is headed for a landing on your kitchen counter. Range hoods are typically rated in sones, and the lower the sone rating the quieter the fan. As a means of comparison, one sone is about the noise that your refrigerator makes, and normal conversational levels are about four sones.