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Heat Recovery Ventilation Systems

Inside a heat recovery ventilator, one fan draws outdoor air in and another fan blows stale room air outside. Both fans blow the air through a central heat-exchange core that extracts the heat from one air stream and transfers it to the other. In some units, the incoming air is filtered on its way through.

Heat Recovery Ventilator   Photo: Honeywell

Heat Recovery Ventilator    Photo: Honeywell

Different manufacturers employ varying technologies to perform this heat-transfer magic. Some send opposing air streams through alternating layers of aluminum plates. Carrier’s Comfort Ventilator utilizes a polypropylene core to transfer heat and separate the incoming and outgoing air streams. Another type of exchanger transfers heat with refrigerant-filled pipes. None of these plate or pipe-type heat exchangers transfer any humidity (water vapor) from one air stream to the other.

Enthalpy-type exchangers have permeable exchangers that let some water vapor through. Honeywell’s Perfect Window and AirXchange models have a desiccant-coated wheel that rotates between the two air streams. Though all HRVs can lower household humidity in winter by exhausting indoor air, the desiccant-coated wheel exchanger can control incoming humidity in summer. For this reason, Honeywell refers to the unit as an “energy recovery ventilator,” in reference to its ability to cut cooling costs. Explains Honeywell, “It takes energy to humidify air. An ERV can reduce the load on air conditioning by rejecting moisture that would normally be coming into the home.”

The NewAire, from Altech Energy, has a fixed-plate type of heat exchanger that uses a Mitsubishi-patented, resin-iMpregnated paper core. Like the Honeywell model, this allows water vapor—and the latent heat it contains—to move from one air stream to the other. In addition to reclaiming some heat, this exchanger pre-humidifies or dehumidifies incoming air to a comfortable range of 35% to 45% in most climates.

Condensation can collect in most HRVs when warm, moist air contacts the exchanger’s surfaces in very cold weather. This moisture can freeze, blocking air flow. Liquid condensation is collected in a condensate pan or carried away by plumbing. Because the Honeywell and NewAire models transfer water vapor, they don’t produce condensation.

Some units have electrical anti-frost heating elements that automatically turn on at about 10 degrees Fahrenheit. In addition tompreventing freeze-up, these slightly warm incoming air. Others have a system of dampers that periodically recirculate room air through the unit when temperatures drop below 20 degrees F.

HRVs are operated by a wall-mounted control. Most manufacturers offer more than one model. For example, with the Honeywell model, you can set the HRV to exchange air continuously, to turn on only when humidity exceeds a certain level, or simply to circulate indoor air until humidity gets too high and then to exchange indoor and outdoor air.

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Ventilation & Fans

Kitchen Hoods & Fans Buying Guide

Stainless-steel range hood ventilates commercial-sized gas stove. This unit includes low-voltage lighting.Michael Higginson / Shutterstock.com

Stainless-steel range hood ventilates commercial-sized gas stove. This unit includes low-voltage lighting.

Cooktop ventilators and range hoods have funnel-shaped interiors designed to pull odors, smoke, and heat up through a filter and blower and exhaust them outside, though they must be sized and installed correctly. (Commercial ranges require a commercial-style ventilation unit, which is quieter and also removes substantial amounts of grease.)

Cabinet-mounted and freestanding ventilators should be sized according to the area they cover plus 3 inches on either side. For example, if your range is a standard 30-inch-wide model, the ventilator should cover 36 by 24 inches, or 6 square feet, and draw 50 to 70 cubic feet per minute (CFM) for a rating of 300 to 420 CFM. If the hood is freestanding, its square footage should be multiplied by 100 CFM to obtain the rating.

No matter how powerful your ventilator is, its efficiency will be compromised if it is improperly placed or if the ductwork is improperly installed. To remove odors, smoke, and heat, the hood should be 24 to 30 inches above the cooktop. The ductwork should not be overly long, made of a material that is anything but smooth, or make more than a few turns. (If installing ductwork is too complicated, a ductless hood, which filters smoke, odors, and steam, though not as effectively, is another option.)

Stainless-steel range hood captures and expels smoke, heat, odors, and steam. Photo: Broan

If your kitchen layout includes a cabinet over the range area, it will take a standard under-cabinet-mounted hood, with the ductwork hidden inside the cabinet. These units frequently feature a light in addition to the fan. If your kitchen does not have a cabinet above the range, you can install a fully exposed unit, as shown above. Because these large units become a commanding feature of the kitchen, they also want to be attractive and so are predictably more expensive.

For situations that do not easily accommodate either a cabinet-mounted or freestanding ventilator, a range with a built-in ventilation system may be the solution. Some, such as the one shown at left, rise up from the rear of the cooktop and can be lowered when not in use. Others are placed in the center of the cooktop, between the left- and right-hand burners. Both types of “down-draft” ventilation systems are adequate alternatives to range hoods in most situations. Their only drawback is that because of their locations, they cannot as effectively ventilate steam from tall pots.

Ornate range hood encloses built-in range equipment. ©Karamysh / Shutterstock.com

Ornate range hood custom made from architectural detailing encloses built-in range equipment.

Ventilation & Fans

Kitchen Hoods & Fans Buying Guide

Stainless-steel range hood ventilates commercial-sized gas stove. This unit includes low-voltage lighting.Michael Higginson / Shutterstock.com

Stainless-steel range hood ventilates commercial-sized gas stove. This unit includes low-voltage lighting.

Cooktop ventilators and range hoods have funnel-shaped interiors designed to pull odors, smoke, and heat up through a filter and blower and exhaust them outside, though they must be sized and installed correctly. (Commercial ranges require a commercial-style ventilation unit, which is quieter and also removes substantial amounts of grease.)

Cabinet-mounted and freestanding ventilators should be sized according to the area they cover plus 3 inches on either side. For example, if your range is a standard 30-inch-wide model, the ventilator should cover 36 by 24 inches, or 6 square feet, and draw 50 to 70 cubic feet per minute (CFM) for a rating of 300 to 420 CFM. If the hood is freestanding, its square footage should be multiplied by 100 CFM to obtain the rating.

No matter how powerful your ventilator is, its efficiency will be compromised if it is improperly placed or if the ductwork is improperly installed. To remove odors, smoke, and heat, the hood should be 24 to 30 inches above the cooktop. The ductwork should not be overly long, made of a material that is anything but smooth, or make more than a few turns. (If installing ductwork is too complicated, a ductless hood, which filters smoke, odors, and steam, though not as effectively, is another option.)

Stainless-steel range hood captures and expels smoke, heat, odors, and steam. Photo: Broan

If your kitchen layout includes a cabinet over the range area, it will take a standard under-cabinet-mounted hood, with the ductwork hidden inside the cabinet. These units frequently feature a light in addition to the fan. If your kitchen does not have a cabinet above the range, you can install a fully exposed unit, as shown above. Because these large units become a commanding feature of the kitchen, they also want to be attractive and so are predictably more expensive.

For situations that do not easily accommodate either a cabinet-mounted or freestanding ventilator, a range with a built-in ventilation system may be the solution. Some, such as the one shown at left, rise up from the rear of the cooktop and can be lowered when not in use. Others are placed in the center of the cooktop, between the left- and right-hand burners. Both types of “down-draft” ventilation systems are adequate alternatives to range hoods in most situations. Their only drawback is that because of their locations, they cannot as effectively ventilate steam from tall pots.

Ornate range hood encloses built-in range equipment. ©Karamysh / Shutterstock.com

Ornate range hood custom made from architectural detailing encloses built-in range equipment.

Ventilation & Fans

Bathroom Fan Buying Guide

Today’s homes are designed and built to be more airtight and energy efficient than ever, so ventilating the pollutants from cooking, showering, and cleaning is vital to the health of the residents and to the structural integrity of the home.

A bathroom ventilation fan is sold as a unit, ready for connection to wires and the vent. Photo: Panasonic

Learning how to properly ventilate the home, especially the bathroom, is as important to the home as it is to the homeowners.

According to the Home Ventilation Institute, the industry’s trade association, during a shower, the humidity level in a bathroom can reach that of a tropical rain forest—uncomfortable and hot. Just the simple act of showering can produce a breeding ground for mold, mildew, and micro-organisms that can not only damage your home but also affect your well-being.

Mold in the bathroom is especially problematic. Mold is a fungus that thrives in warm, dark, humid environments. It spreads via spores that grow on wet or moist organic surfaces such as wood, wallboard, and bathroom tile. The only effective way to prevent mold is to attempt to keep indoor moisture levels low. Mildew is simply a type of mold that spreads particularly well in organic, moisture-rich environments.

The main problem with showering when there is not proper ventilation is the build-up of moisture, which can deteriorate joists above and framing around the bathroom, crack or peel paint, ruin gypsum wallboard, warp cabinets, and erode fixtures. The formation of mildew on tile grout is encouraged by these conditions.[GARD align=”left”]

However, bathroom exhaust fans, ducted to the outside, effectively remove moisture during and after a shower and help prevent the growth of harmful bacteria as well as assist in eliminating unwanted bathroom smells.

The primary use of an exhaust fan is to extract moist and stale air from the bathroom and deposit it outside the home. An exhaust fan is designed to be out of sight, anchored to the ceiling between joists, with an exhaust duct leading to the outside. The only part of an exhaust fan you should see is the grille.

If you’ve spent years not utilizing your bathroom exhaust fan because of the noise, consider that some of the latest fans are nearly inaudible. Today’s exhaust fans no longer sound like a Boeing 757 landing on top of your home, plus, they are easy to install.

Bathroom Fan Features

Useful features that come with many bathroom exhaust fans include:

• A ceiling light—when the switch is turned on, both fan and light are activated.

• Activation of the fan according to preset humidity levels.

• A motion sensor that turns on the fan automatically if someone enters the bathroom and stays running for a predetermined amount of time.

• A timer switch, which, after it is activated, will keep the fan running for the time indicated, even after the light is turned off.

• An allergen-reducing filter.

Before You Buy a Bathroom Fan

Before purchasing a new or replacement bathroom exhaust fan, consider the following:

• Replacing an existing exhaust fan is a lot less complicated than a new installation because the latter means routing the exhaust duct through the ceiling or a wall. For information on how to install a bathroom fan, please see How to Install Bathroom & Kitchen Fans. If you plan to connect a bathroom exhaust fan yourself, make sure you understand your home’s electrical wiring and how to turn off the power at the circuit box.

• Install the fan as near or directly over the shower as possible to capture moisture immediately. Make sure your exhaust fan terminates outside, not in the crawlspace or attic. The venting that leads to the outside should point downward to prevent rain or debris from entering the house.

• Always follow the manufacturer instructions that accompany the purchase of your exhaust fan.[GARD align=”right”]

• Check with your local planning department to see if a permit is required for installation.

• Look for fans that meet the energy-efficient requirements of Energy Star.

• Make sure your fan is UL listed for wet locations. A UL-recognized housing has a tough protective shell that is certified for performance in wet regions.

Using a Bathroom Fan

• If you have a steam shower, use a separate fan on a timer so that it can be shut off during shower use and then run afterward to dry the shower stall.

• Don’t run your exhaust fan any longer than necessary. While an exhaust fan is operating, it is exhausting air and moisture to the outside; however, at the same time, whatever the fan blows out can leak back into the house somewhere else.

• You do, however, need to run the fan for a time period that will properly remove any moisture and provide a complete exchange of room air. Running an exhaust fan for only a few minutes after a long, hot shower or a relaxing bubble bath is not sufficient. It takes approximately 20 minutes to remove all moisture for most standard-sized bathrooms.

Featured Resource: Find Pre-Screened Local Bathroom Fan Installation Help

Ventilation & Fans

Buying a Whole-House Fan

Expert, unbiased advice on how to buy a whole-house fan, including options, sizing, when and how to use them, and manufacturers.

Are you tired of soaring electrical bills and having to run your air conditioner day and night in summer? Have you developed allergies, likely brought on by stale, non-ventilated, “shut-in” air? If so, you might consider installing a whole-house fan. This can provide much needed ventilation and cool your home using far less energy than that consumed by an air conditioner.[GARD align=”left”]

According to the U.S. Department of Energy, whole house fans are a simple and inexpensive method of cooling a house. They provide excellent ventilation, lower indoor temperatures, and improve evaporative cooling. The cost for a whole house fan is $150 to $350 versus the cost for central air conditioning, which runs $2,000 to $4,000 or more. In addition, whole house fans use one-quarter the power of central air conditioning.

The word “ventilation” comes from the Latin word for “to fan.” In the case of houses, this means out with the hot air and in with the cool.

The attic is the target location for a whole house fan because hot air rises, and, especially during summer, attic temperatures can reach 130 degrees F. Because the attic is not only at the top of your home but mostly enclosed, the hot air gets trapped in the attic, causing the interior of the house to heat up.

A whole house fan goes in the ceiling between a home’s uppermost rooms and the attic. It pulls cool outdoor air through open windows and doors and circulates it throughout the house. The warmer air in the house is drawn up into the attic where it is then pushed outside through roof vents. The attic fan is far more effective at expelling the hot attic air than passive attic vents working on their own.

Whole house fans cool the entire house using outside air instead of “conditioning” inside air. The truly “cool” part about them is that they keep air moving through a home, and moving air feels cooler than still air.

Whole House Fans vs. Attic Fans

What is the difference between a whole house fan and an attic fan? Whole house fans suck out hot air from the house, force it into the attic, and then exchange it with cooler outside air via vents. Attic fans only serve to remove some hot air from the attic. They are still effective, however—they can save you 30% on cooling costs by getting rid of trapped super-hot air that collects in the attic and then backs up into the house’s living spaces.

Attic fans can lower upstairs temperatures by 10 degrees F., lengthen roof life by keeping shingles cooler, and, with an added optional humidistat, keep attics dry during winter months

Use of an attic fan is easy because it goes on or off automatically via a thermostat. The attic fan only runs when it is beneficial.

Look for these three things in an attic fan:

1) All metal construction—do not buy a fan made of plastic

2) A quality thermostat because you do not want to have to crawl into your attic to manually turn the fan on and off.

3) A fire stat, which shuts the attic fan off under extremely high temperatures, such as if your home is on fire.

Attic fans come in rooftop and gable-end models and can be powered by electricity or by solar energy.

Whole House Fans Options

If you’re considering a whole house fan to complement your air conditioner, or to take the place of your AC, you first must evaluate your needs. The following guidelines will help:[GARD align=”left”]

Go into your attic to see what you have to work with. A sign of poor ventilation is an unbearably hot attic in summer. Check for moisture, evident from any mold, mildew, rusted nailheads, damp or compressed insulation, or wood rot.

Also look for vents. There are gable vents, roof louvers, intake vents, and soffit and eave vents. Note the size and location of each. Finally, estimate the attic’s square footage. According to most building codes, you need 1 square foot of vent area for each 150 square feet of attic floor space. Do not underestimate your ventilation needs. Building codes specify minimums; you may want to increase those to ensure proper ventilation.

Make sure to have a balance of intake and exhaust avenues to properly ventilate your home. In the attic, remember that the flow of air is limited by the amount of intake. If a ventilation system is balanced, half of it will be provided by exhaust vents in the upper portion of your attic, with the other half provided by intake vents.

Call your utility company. Many offer rebates for whole house fan installation. Also explore whether any state or federal tax credits are available. Many companies offer 10-year warranties. Make sure you inquire before making a purchase.

Traditional whole house fans tended to be noisy, consume more energy, require maintenance (belt-driven ones need the belts changed periodically), and were not well insulated. The newer whole house fans are well engineered to take care of these problems in multiple ways. Look for:

• The number of blades—the more blades, the quieter the fan will be because each blade has to do less work. Have the fan isolated from your home’s framing with foam strips or rubber mountings. That way the motor hum will not resound through the framing and drywall. Also make sure your unit has a welded frame so it will not loosen up and begin to squeak.

• Quality shutters—the better the quality, the less thumping noises will occur when the unit shuts off. The latest fans have self-sealing insulated shutters that close when the fan is not operating, which prevents heat from escaping when the unit is not in use.

• A timer—recommended over a thermostat, which could turn the fan on when no one is home (i.e., no windows or doors are open), or a fire in the fireplace could trigger the fan to go on.

Ideally, look for a larger fan that will run well at a lower speed, thereby using less energy. A heavier unit is also recommended because it rests on foam weatherstripping, held down only by its own weight.

Whole house fans are generally easy to install. Direct-drive models are the most do-it-yourself friendly since no attic joists need to be cut. Belt-drive whole house fans use an integrated pulley system, which takes longer to install, but a belt-drive unit provides for a smoother and quieter operation.

Sizing a Whole House Fan

When selecting a whole house ventilation fan system, an important factor to consider is what size it should be. Whole house fans are rated according to the cubic feet per minute (CFM) of air they can move. So, the bigger your house, the bigger the fan it will need.

If your home has standard 8-foot-high ceilings, just multiply the home’s overall square footage by 3 to calculate the right size of fan for the house in CFMs. For example, if your home is 2,000 square feet, figure 2,000 x 3 = 6,000. If some of your ceilings are higher than 8 feet, buy a slightly larger one.

For a 2,300-square-foot house, the recommended size of a belt-drive unit is 36 inches (which will cover 6,900 CFM). Both belt-drive and direct-drive units for a 1,900-square-foot house require a 30-inch unit and will cover 5,700 CFM. For a 1,500-square-foot house, the direct- drive 24-inch unit, which covers 4,500 CFM, is recommended.

If you choose a high-speed fan, you need to make sure there’s enough venting for it. A good rule of thumb is 1 square foot of venting area for every 750 CFM. Another way to look at it is, provide the same amount of venting as the size of the shutter hole in the ceiling.

When & How to Use a Whole House Fan

For optimal effectiveness, use your whole house fan in the late afternoons, evenings, and/or early mornings when the outside temperatures are cooler than inside temperatures.

Here are a few basic tips for using a whole-house fan:

• Turn off the central air conditioning when using a whole house fan. Otherwise, you will expel all of that expensively cooled air in your home!

• Open the windows and doors. If you do not, the fan may cause your gas-burning appliances, furnace, or water heater to backdraft exhaust fumes and carbon monoxide into your home.

• Do not have a fire going in the fireplace. A fire will not vent properly because of the change of air pressure that a whole house fan causes.

There are also some drawbacks to whole house fans:

• They can only cool the inside of the house to the outside temperature, so if it is hot outside, it will be just as hot inside, except for the coolness offered by air movement.

• Unlike an air conditioner, a whole house fan cannot dehumidify the air.

• A whole house fan can draw dust and pollen into the house.

• In winter months, whole house fans could present energy loss as heated room air leaks into the attic. A shutter or cover can minimize this problem.

Whole House Fan Manufacturers

West Connection Entertprises’ Quiet Cool System is a multifan, multilocation system that moves 1,500 CFM of air per fan. It is easy to install and has insulated self-closing damper doors to prevent unwanted air loss.

Quiet Cool fans are installed in a hanging position from the attic rafters, which puts the fans as far away from your living space as possible to reduce noise.

They can have multiple on/off switches if you want one fan to run in one part of the house but not in another part. The Quiet Cool has no motorized doors or belts to replace, and the fan blades are not plastic. It comes with a 10-year warranty and costs $1,350.

R.E. Williams offers three types of whole house fans, with an estimated air exchange of five minutes for a 1,500-square-foot home and a 10-minute air exchange for homes of 3,000 square feet:

1) The HV1000 whole house fan requires no maintenance and has an R-22 insulated door, which, when not in use, forms an airtight seal between your attic and living space. This basic fan costs $550.

2) The “Ghost” (shown above right) is a two-speed whole house fan with a remote on/off switch. This is an easily installed and energy-efficient large-diameter fan that closes and seals when not in use. It comes with a three-year warranty and costs $1,250.

3) The “Superfan” (shown at right) is an energy-efficient whole house fan that does not require any maintenance. It has one central unit with a German-made fan motor known as a backward curved impeller motor, designed to pull large amounts of air through the air ducts quietly.

It also has an on/off switch and a wireless remote control option. The Superfan is rated for all homes up to 3,000 square feet, though it is not recommended for homes in very cold climates. The cost is $1,550, with installation estimated at between $400 and $500.

Find a Pre-Screened Local Whole-House Fan Installation Contractor

Ventilation & Fans

Best Whole House Fan Buying Guide

Expert, unbiased advice on how to buy a whole-house fan, including options, sizing, when and how to use them, and manufacturers.

whole house fanAir Vent, Inc.

24-inch whole-house fan pulls hot air out of the house. Buy on Amazon.

Are you tired of paying soaring electrical bills and running your air conditioner day and night in summer? Have you developed allergies, likely brought on by stale, non-ventilated, “shut-in” air? If so, you might consider installing a whole-house fan. This can provide much needed ventilation and cool your home using far less energy than that consumed by an air conditioner.[GARD align=”left”]

Whole House Fan Benefits & Drawbacks

According to the U.S. Department of Energy, whole house fans are a simple and inexpensive method of cooling a house. They provide excellent ventilation, lower indoor temperatures, and improve evaporative cooling. The cost for a whole house fan is $150 to $350 versus the cost for central air conditioning, which runs $2,000 to $4,000 or more. In addition, whole house fans use one-quarter the power of central air conditioning.

There are also some drawbacks to whole house fans:

• They can only cool the inside of the house to the outside temperature, so if it is hot outside, it will be just as hot inside, except for the coolness offered by air movement.

• Unlike an air conditioner, a whole house fan cannot dehumidify the air. If you want to dehumidify, see Dehumidifiers Buying Guide.

• A whole house fan can draw dust and pollen into the house. To solve air quality problems, see Home Air Purifier & Cleaner Buying Guide.

• In winter months, whole house fans could present energy loss as heated room air leaks into the attic. A shutter or cover can minimize this problem. To solve this issue, you can buy an insulated whole house fan. These kinds of fans have insulated doors that shut tight when the fan is not in operation.

• A whole-house fan adds noise to your living environment. A fan, especially located near bedrooms, can detract from the quality of your life (and sleep). See 8 Soundproofing Secrets for a Quieter Home.

How a Whole House Fan Works

The word “ventilation” comes from the Latin word for “to fan.” In the case of houses, this means out with the hot air and in with the cool. The attic is the target location for a whole house fan because hot air rises, and, especially during summer, attic temperatures can reach 130 degrees F when heat gets trapped in the attic. This causes the interior of the house to heat up. (For more, see How Ventilation Works.)

A whole house fan goes in the ceiling between a home’s uppermost rooms and the attic. It pulls cool outdoor air inside through open windows and doors and circulates it throughout the house. The fan draws warmer air in the house up into the attic where increased pressure pushes the hot air outside through roof vents. An attic fan expels the hot attic air far more effectively than passive attic vents working on their own.

Whole house fans cool the entire house using outside air instead of “conditioning” inside air. The truly “cool” part about them is that they keep air moving through a home, and moving air feels cooler than still air.

Whole House Fans vs. Attic Fans

What is the difference between a whole house fan and an attic fan?

Whole House Fans

Whole house fans suck out hot air from the house, force it into the attic, and then exchange it with cooler outside air via vents. Attic fans only serve to remove some hot air from the attic. Attic fans can, however, save you 30% on cooling costs by getting rid of trapped super-hot air that collects in the attic and then backs up into the house’s living spaces.

gable vent fanBroan

An electric gable fan vent closes when off. Buy on Amazon.

Attic Fans

Attic fans can lower upstairs temperatures by 10 degrees F., lengthen roof life by keeping shingles cooler, and, with an added optional humidistat, keep attics dry during winter months

Use of an attic fan is easy because it goes on or off automatically via a thermostat. The attic fan only runs when it is beneficial.

Look for these three things in an attic fan:

1) All metal construction—do not buy a fan made of plastic.

2) A quality thermostat because you do not want to have to crawl into your attic to manually turn the fan on and off.

3) A firestat, which shuts the attic fan off under extremely high temperatures, such as if your home is on fire. You can buy a firestat online.

Attic fans come in rooftop and gable-end models and can be powered by electricity or by solar energy.

For more about attic fans, see Attic Fans & Ventilation Tips.

Whole House Fan Evaluation

If you’re considering a whole house fan to complement your air conditioner, or to take the place of your AC, you first must evaluate your needs. The following guidelines will help:[GARD align=”left”]

Go into your attic to see what you have to work with. A sign of poor ventilation is an unbearably hot attic in summer. Check for moisture, evident from any mold, mildew, rusted nailheads, damp or compressed insulation, or wood rot.

Do not underestimate your ventilation needs. According to most building codes, you need 1 square foot of vent area for each 150 square feet of attic floor space.

 

Attic Vents

Also look for vents. There are gable vents, roof louvers, intake vents, and soffit and eave vents. Note the size and location of each. Finally, estimate the attic’s square footage. Do not underestimate your ventilation needs. According to most building codes, you need 1 square foot of vent area for each 150 square feet of attic floor space. Building codes specify minimums; you may want to increase those to ensure proper ventilation.

home ventilation©Don Vandervort, HomeTips

Many appliances and vents combine to properly ventilate a home.

Make sure to have a balance of intake and exhaust avenues to properly ventilate your home. In the attic, remember that the the amount of intake limits the flow of air. With a balanced ventilation system, exhaust vents in the upper portion of your attic provide half of it, while intake vents provide the other half.

Rebates & Credits

Call your utility company. Many offer rebates for whole house fan installation. Also explore whether any state or federal tax credits exist.

Many companies offer 10-year warranties. Absolutely check out the warranty before making a purchase.

Old whole house fans tended to be noisy, consume considerable energy, require frequent maintenance (belt-driven ones need the belts changed periodically), and are not well insulated. Better engineered new whole house fans take care of these problems in multiple ways.

Whole House Fan Options to Consider

Look for:

• A quiet fan. Because whole-house fans are running most of the time, it’s important for them to be quiet. Fans are rated by “sones.” According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), whole-house fans should not be louder than 1.0 sones.

Belt-drive whole house fans that use an integrated pulley provide for a smoother and quieter operation than direct-drive fans.

Generally speaking, the more blades a fan has, the quieter it will be. Also make sure your unit has a welded frame so it will not loosen up and begin to squeak. Have the fan isolated from your home’s framing with foam strips or rubber mountings. That way the motor hum will not resound through the framing and drywall.

• Quality shutters. The better the quality of the shutters or doors, the less thumping noises will occur when the unit shuts off. As mentioned above, energy-saving fans have self-sealing insulated shutters that close when the fan is not operating, which prevent heat from escaping when the unit is not in use.

• A timer control. A whole-house fan timer control is recommended over a thermostat, because a thermostat can turn the fan on when no one is home (i.e., no windows or doors are open). In addition, a fire in the fireplace could trigger the fan to go on if it’s controlled by a thermostat.

• Size. Ideally, look for a large fan that will run well at a lower speed, thereby using less energy. A heavy unit may also be quieter than a lightweight model because it rests on foam weatherstripping, held down only by its own weight. See more about size below.

• Installation method. Most whole house fans are relatively easy to install. Direct-drive models are the most do-it-yourself friendly because, for most, no attic joists need to be cut. Belt-drive whole house fans that use an integrated pulley system take longer to install, but a belt-drive unit provides for a smoother and quieter operation.

Sizing a Whole House Fan

When selecting a whole house ventilation fan system, an important factor to consider is what size it should be. Whole house fans are rated according to the cubic feet per minute (CFM) of air they can move. So, the bigger your house, the bigger the fan it will need to move the air effectively.

measuring tapeStanley

25-Foot Measuring Tape. Buy at Amazon.

If your home has standard 8-foot-high ceilings, just multiply the home’s overall square footage by 3 to calculate the right size of fan for the house in CFMs. For example, if your home is 2,000 square feet, figure 2,000 x 3 = 6,000 CFM. If some of your ceilings are higher than 8 feet, buy a slightly larger one.

For a 2,300-square-foot house, the recommended size of a belt-drive unit is 36 inches (which will cover 6,900 CFM). Both belt-drive and direct-drive units for a 1,900-square-foot house require a 30-inch unit that can handle  5,700 CFM. For a 1,500-square-foot house, the direct-drive 24-inch unit, which covers 4,500 CFM, is recommended.

If you choose a high-speed fan, you need to make sure there’s enough attic venting to expel its output. A good rule of thumb is 1 square foot of venting area for every 750 CFM of fan. Or you can simply provide the same amount of attic venting as the size of the shutter hole in the ceiling.

When & How to Use a Whole House Fan

For optimal effectiveness, use your whole house fan in the late afternoons, evenings, and/or early mornings when the outside temperatures are cooler than inside temperatures.

Here are a few basic tips for using a whole-house fan:

• Turn off the central air conditioning when using a whole house fan. Otherwise, you will expel all of that expensively cooled air in your home!

• Open the windows and doors. The fan needs inbound fresh air. If you do not open windows and doors, the fan may cause your gas-burning appliances, furnace, or water heater to backdraft exhaust fumes and carbon monoxide into your home.

• Do not have a fire going in the fireplace. A fire will not vent properly because of the change of air pressure that a whole house fan causes.

 

Whole House Fan Manufacturers

QuietCool whole house fanQuietCool

Ducted whole-house fan system is particularly quiet because the fan is located remotely. Buy on Amazon.

Here is a closer look at a few popular choices:

The QuietCool System is a multifan, multilocation system that moves 1,500 CFM of air per fan through a ducted system, much like a forced-air heating and AC system. It is easy to install and has insulated self-closing damper doors to prevent unwanted air loss.

QuietCool fans are installed in a hanging position from the attic rafters, which puts the fans as far away from your living space as possible to reduce noise.

They can have multiple on/off switches if you want one fan to run in one part of the house but not in another part. The QuietCool has no motorized doors or belts to replace, and the fan blades are not plastic. It comes with a 10-year warranty.

 

Tamarack Technologies whole house fanTamarack Technologies

The Tamarack Technologies whole house fan has R-50 insulated doors that seal up the attic when the fan isn’t in use. Buy on Amazon.

The Tamarack Technologies HV1600 whole house fan requires no maintenance and has an R-50 insulated doors, which, when not in use, form an airtight seal between your attic and living space.

 

whole house fanTamarack Technologies

“The Ghost” is a 2-speed fan designed for easy installation. Buy on Amazon.

The “Ghost”  is a two-speed whole house fan with a remote on/off switch. This is an easily installed and energy-efficient large-diameter fan that closes and seals when not in use. It comes with a three-year warranty.

Superfan whole house fan

Multi-ducted “Superfan” has a large plenum with ducts that draw air from several rooms.

 

The “Superfan” is an energy-efficient whole house fan that does not require any maintenance. It has one central unit with a German-made fan motor known as a backward curved impeller motor, designed to pull large amounts of air through the air ducts quietly.

It also has an on/off switch and a wireless remote control option. The Superfan is rated for all homes up to 3,000 square feet, though it is not recommended for homes in very cold climates. The cost is $1,550, with installation estimated at between $400 and $500.

ducted whole house fanCentric Air

Ducted whole-house fan keeps motor noise away from living spaces. Buy on Amazon.

TheCentric Air is a ducted, two-speed whole-house fan. Its collection plenum and grille fits between 16-inch or 24-inch on-center ceiling joists and the fan motor is located at the far end of the duct, keeping the motor noise away from the living quarters. This makes this type of fan a good choice over bedrooms or other living spaces where quiet is important.

Find a Pre-Screened Local Whole-House Fan Installation Contractor


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