Dehumidifiers Carlsbad CA
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San Diego, CA
San Diego, CA
Humidity in the Home
As families are spending more and more time together in the home, kitchens are becoming popular gathering spots. As a result, they're getting bigger. At the same time, many homeowners are opting for professional-grade kitchen appliances, all of which has a significant effect on a home's ventilation and indoor air quality.
The byproducts of cooking -- the moisture, grease, odors, heat and even carbon monoxide from gas ranges -- can be destructive to your home, and even life-threatening. Our grandparents homes almost always were drafty enough to provide for incidental ventilation, as much of the steam and gases generated during cooking were able to escape through cracks and crevices in the building envelope. But with today's tighter, more energy-efficient homes, we need to ventilate our kitchens mechanically to keep the indoor environment comfortable and healthy.
Cooking up Trouble
Your grandmother's house may have been filled with comforting cooking odors, but you can bet they weren't very clean or healthy, says Brian Wellnitz, product manager for kitchen ventilation at Broan-NuTone. That grease, smoke, moisture and other stuff that gets released through cooking can settle into fabrics, wallpaper and furniture and cause damage to those materials. They can even damage your cabinetry and condense on windows or inside wall cavities, causing mold and rot problems.
Probably the most important factor in maintaining good indoor air quality is controlling the humidity level inside the home. The ideal moisture level is between 30 and 60 percent. Less than that can cause wood to shrink, increase dust, and aggravate respiratory, throat and skin irritations. Humidity levels above 60 percent in a home can lead to mold, mildew and eventually rot.
The major source of indoor humidity is people. Showering and bathing, cooking and even breathing all contribute to indoor moisture levels. Your home's HVAC system should be able to handle the moisture released through breathing and perspiration, but to handle the concentrated levels of humidity from showering and cooking, spot ventilation is necessary.
Bathroom vent fans have been common for many years, but most people are just catching on to proper kitchen ventilation. We should have been paying this much attention to kitchen ventilation 50 years ago, but the building industry wasn't as savvy then, says Ron Cook, a kitchen designer and owner of Cook's Design Studio in Sarasota, Fla. Now, with the popularity of large, professional cooking appliances, especially gas cooktops, people are realizing the need for proper ventilation. Gas appliances release at least twice as much heat and humidity into the air as electric, and the carbon monoxide can be another concern.
Cook stresses that proper ventilation contributes to healthier indoor air and reduces damage to cabinetry and other household items, and also can prevent more catastrophic damage. A properly functioning range hood can help suppress a full-blown fire that could result from a grease flare-up, he explains. In fact, many insurance companies in our area will resist paying on a claim for a kitchen fire if the room wasn't adequately ventilated.
Getting What You Need
Unless your home was built or remodeled in the last 10 or 15 years, chances are you don't have proper kitchen ventilation. According to Cook, at least 80 percent of his past kitchen remodels did not include proper ventilation. Now, new home codes spell out specific requirements, he says. Most local code enforcement agencies will require remodels to meet codes that address sizing, spacing and specs before they'll issue a permit.
Building codes, as well as ventilation guidelines published by the Home Ventilating Institute, an independent testing and certification association for residential ventilation products, are designed to ensure adequate ventilation, says Broan-NuTone's Wellnitz, since they're based on room size and layout as well as the BTU output of cooking appliances and the size of the cooking area. Homeowners should be familiar with the following key points addressed in those guidelines.
A deep hollow cavity under the hood (called the sump) will collect more air than a shallow one, but many of today's styles are moving toward sleeker designs. If you desire a slim, shallow hood and your cooking habits tend to generate a lot of heat and moisture, you might want to check into newer-technology hoods that pump air out around the edges, creating a flow that traps air from the cooking surface until the fan can remove it.
It is always best to maximize capture area whenever possible, Wellnitz says. It is better to overlap the cooking surface by at least 3 inches on either side and extend at least 18 inches to the front. Cook says he usually extends his capture area to overlap 6 inches on either side to handle the professional-style gas cooktops his customers like.
CFM The amount of air a fan can move is calculated in cubic feet per minute (CFM). The minimum requirement is usually 40 CFM for every linear foot of cooking surface. That number increases to 50 CFM for island range hoods.
However, the Home Ventilating Institute recommends 100 CFM per linear foot for wall-mounted units and 150 CFM per linear foot for island hoods. Longer ductwork, larger ranges and remote fans (located in or at the end of the ductwork as opposed to under the hood) require additional upgrades in CFM.
In high-end kitchens, the designer or sometimes the HVAC installer will specify the CFM needed, Cook says. But for homeowners redoing their kitchens without the aid of these professionals, Cook notes that there is enough literature available with explicit specifications, so they can specify their own hoods.
Sones Fan noise is measured in sones, with 1 sone being about as noisy as a new refrigerator and normal conversation equaling about 8 sones. Most kitchen ventilation systems run in the 3- to 8-sone range, but many new models now run at less than 1 sone. Generally speaking, the more powerful the unit, the louder it will be. But higher-quality units and those with fans mounted remotely will be the quietest.
You have to make sure you install a fan that's quiet enough so people will use it, says Karen Collins, marketing communications manager at Broan-NuTone. If it's too noisy, people won't turn it on.
Cook uses ventilation products from Fantech because he likes their in-line system, in which a silencer unit (think car muffler) is mounted in the ductwork between the hood and the remote fan. It greatly reduces noise, so people are more apt to turn it on and leave it on as long as necessary, he explains.
Ductwork Generally speaking, kitchen ventilation ducts should be no more than 30 feet long. Turns and transitions to smaller ducts should be minimized to keep the air moving.
The actual size of your ducts will depend on the size of the range hood; a 600-CFM unit needs at least a 7-inch round or 3.25-by-10-inch rectangular duct. As always, the duct should be sealed and airtight.
Ducts should be vented to the outside and not the attic or basement. Nonducted range hoods, called recirculating hoods, provide minimal benefits and should be avoided whenever possible. You can almost always find a way to duct to the exterior, Collins says. It's often only a matter of $200 to $300 added to the total cost of the job.
Collins, Cook and Wellnitz agree that whether you specify it yourself or let a professional kitchen designer or contractor handle your kitchen ventilation needs, you should look for products that are tested and certified by the Home Ventilating Institute.
Inflated performance ratings are common on uncertified products, Wellnitz says. HVI independently tests and certifies sone and CFM ratings, so purchasing one of those products will ensure homeowners get what they expect from their kitchen ventilation.
Rob Fanjoy is a freelance writer based in Ypsilanti, Mich