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AC and Heating Tip from AC Express

Exhaust Fans and Proper Home Ventilation

Exhaust Fans and Proper Home Ventilation

Today’s homes are wonders of human achievement. All of human’s history of architecture, material science, and design converge in the modern homes we enjoy today. One achievement of these modern homes is a degree of air tightness far exceeding what was found in homes even as a close as fifty years ago. The ramifications of this are two fold, the positive side is that these air tight homes are great for energy efficiency. It means that the cool air your air conditioner creates in the summer and the warm air your heater creates in the winter will be trapped in your home much more than older houses and that means you’re going to lose less of this conditioned air and your HVAC system won't have to work as hard to achieve a certain temperature in the home when air conditioning and heating in Austin.

The downside of this system is that it means much more thought must be put towards the proper ventilation of the home. As great as high quality insulation and energy efficient air tightness is it goes counter to the fact that some degree of ventilation is required for a home to not succumb the problems associated with stale air and poor air quality. In this tip of the day, we’re going to cover the subject of home ventilation and how it happens, focusing on exhaust fans in the kitchen and the bathroom and how to properly use them.

Ventilation and Air Quality

There are a number of things that influence the quality of air you’re going to have in your home, too many to cover in one short article. But one that many people ignore is ventilation. The ventilation of a home is a measure of how much exchange there is between the circulated air in the home and the fresh air outside of the home. Too much exchange there and you’ve got poor energy efficiency because too much of the conditioned air is leaking out. Too little exchange and you've got a case of stale air being endlessly circulated in the home.

One specific result of too little ventilation that affects air quality is excessive humidity levels. High indoor humidity can spur mold growth. High humidity may result from poor construction or rehabilitation, site design that does not properly manage water, and/or inadequate air exchange. A reasonable target for relative humidity is 30-60 percent. A low cost hygrometer, available at hardware stores, can be used to measure relative humidity. In cool climates, inadequate ventilation in the winter can contribute to excessive moisture and humidity because normal activities create moisture (cooking, bathing, breathing), and there is insufficient natural ventilation or mechanical ventilation (fans, exhaust systems) to remove the moisture. In warmer climates, such as ours in Austin, heating, ventilation, and air conditioning system can pull warmer, humid air inside. In this case, the ventilation system may help create indoor humidity problems unless the system also dehumidifies the air.

Poor ventilation leads to contaminants that enter the household continuing to circulate throughout the house rather than being properly filtered and ventilated out. This is especially true when it comes to potentially dangerous or irritating contaminants that come from inside the house in the first place. This include chemicals used in the construction or renovation of buildings (e.g., glues, off-gassing from carpets, emissions from particle board, cleaning compounds). In addition, appliances that burn gas can produce particulates and carbon monoxide. Incomplete combustion and poor ventilation of these appliances (cook stoves, gas furnaces, gas boilers, and gas water heaters) can contribute to indoor contaminants. Gas cook tops should be used with fans that send exhaust outside. Gas-fired heating appliances should be sealed and power-vented systems installed to remove products of incomplete combustion. Wood-burning stoves can also create particulates and must be vented outside.

Types of Ventilation

There are two broad types of ventilation systems, one you’re probably used to and one that might be slightly less familiar. The first and more commonly known about type of ventilation is spot ventilation. This includes the familiar kitchen fan and bathroom fan. We call this spot ventilation. Spot ventilation draws air from a particular location (e.g., bathroom, kitchen) and exhausts it to the outside.

The second type is called dilution ventilation. Dilution ventilation addresses the entire living space. Air changes (exchanging indoor air with outdoor air) and air cleaning help determine the effectiveness of dilution. Air changes result from a combination of natural ventilation (infiltration; leakage; windows) and mechanical ventilation. Air cleaning occurs when particulates are filtered and when air is dehumidified to remove moisture. The goal is to provide sufficient changes to ensure a healthy environment.

Bathroom Ventilation

Exhaust fans in the bathroom do an important job. The bathroom is home to a lot of moisture and thanks to the fact that the room and its surroundings are generally windowless there isn’t a lot of opportunity for natural ventilation here. Daily bathroom activities such as bathing and showering can add a considerable amount of humidity to your home’s air supply. Without sufficient bathroom ventilation, that extra airborne moisture can wreak havoc in your home. It can promote mold and mildew growth, make the air feel too sticky and warm, put undue strain on the HVAC equipment and increase its energy consumption. Following these ventilation tips can help you prevent these problems.

First of all, when designing a bathroom ventilation system, you need to make sure your exhaust fans are going to be the right size for the job. To rid the average-size bathroom of excess moisture, make sure you have one CFM of fan capacity per square foot of space. Bathrooms over 100 square feet in size need an additional 50 CFM for each toilet, bathtub or shower, and an extra 100 CFM for a jetted bathtub. After figuring out the right capacity, you can choose a single, powerful fan or use multiple smaller units.

The next most important factor in bathroom exhaust is the location of the fans. When you install a fan, locate it in the ceiling above a fixture such as the bathtub or shower enclosure. Separate toilet areas need their own dedicated unit. Make sure fans are placed a distance from the HVAC air vent, and undercut the bathroom door so replacement air is easily pulled in from outside.

The last important factor is to of course use the fan, and use it often enough. For effective ventilation, the fan needs to run for at least 15 minutes after each bathroom use, and you can choose models with features that make this easy. Look for fans with built-in sensors that start them up when the door opens and timers that shut them off automatically. You can even choose a unit with a humidity sensor so it runs whenever the air contains enough moisture.

Many people avoid using their bathroom fans partially because of the noise.This is a common problem which occurs when the fan is not properly installed. Poor installation also frequently involves a lack of insulation, which can cause heat to escape into the attic. Fortunately, all of this can be avoided with the appropriate exhaust fan and the proper installation. Bathroom exhaust fans are a crucial element that should not be overlooked in your home. It is important that you install an exhaust fan of high quality, that way you can rest assured knowing that you have made an excellent investment.

Kitchen Ventilation

The kitchen is the second place in the home that requires the most attention when it comes to ventilation. The stove is a source of a lot of humidity and air exchange, meaning proper ventilation above the range is absolutely essential. Many people do not consider the kitchen range hood to be an important part of a house’s mechanical ventilation system, but they are. Like it or not, the kitchen exhaust has to play nice with the rest of the house's mechanical system. This is especially important in tight houses and energy efficient retrofits.

When it comes to advanced kitchen ventilation exhaust systems, there are two types; those that run intermittently and those that run continuously. Range hoods typically turn on when a person turns them on and they turn off when a person turns them off. This is the intermittently run kind. Continuous exhaust fans must be quiet, and more energy efficient if they are to be useful. Kitchen fans operated intermittently should move 100 CFM of air or more. Energy Star recommends selecting a fan with a rating of 150 to 200 CFM to pull at least 100 CFM when measured. Those that run continuously should move 25 CFM of air. Energy Star recommends fans that will get you at least 5 air changes per hour based on the kitchen's volume.

The kitchen fan should be in use whenever the range top is in use. It may also be wise to have the fan running for 15 to 30 minutes after cooking to ensure proper ventilation and circulation. Both bathroom and kitchen exhaust fans are important features in any home, especially modern homes that are well insulated and air tight.

Ventilation and Heating Repair in Austin

Ventilation is a big part of keeping a healthy and comfortable home. It’s right there in the acronym that we use to refer to home air treatment and control, HVAC. Despite being right in the middle of the acronym, ventilation tends to get ignored as a subject when compared to its more popular brothers, heating and air conditioning. Such things aren’t possible without ventilation though, so if you’re building a new house or retrofitting an old one, make sure proper thought and consideration is given to how it is going to be ventilated.

And don’t forget your heating system’s maintenance, the air conditioning as well. If you need heater repair in Austin, consider AC Express. We’re an Austin heater repair company whose service area includes everything from Hutto and Taylor to Pflugerville and Round Rock. For same day heater repair, call today!


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