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Why do we need to understand the different types of ventilation systems? Well, we all know about natural ventilation. As evident from its name, natural ventilation allows fresh outdoor air to enter while replacing indoor air in a home. However, this may not be considered the best option in modern times because nowadays, most houses are sealed to conserve energy. If natural ventilation is not efficient, we can go for spot ventilation.
Spot ventilation can be combined with natural ventilation to improve its overall effectiveness. It removes indoor air pollutants and moisture. Some examples of spot ventilation are localized exhaust fans used over kitchen ranges and in bathrooms. Now, if both these systems don’t work, you might need to consider a proper ventilation strategy for your house. And this is where ventilation systems come in.
Ventilation systems include all the fans, vents, and ventilation equipment in your home. These equipment work together to exchange indoor and outdoor air without resulting in energy wastage. Ventilation systems can differ from house to house, depending on the climate and structural requirements. And that’s why you need to understand the different types of ventilation systems — so that you know the differences and make an informed decision.
Exhaust ventilation systems function on the principle of pressure difference. They reduce the interior air pressure as compared to the outdoor air pressure, thereby, extracting indoor air from the house. External air comes in via intentionally created, passive vents.
If you live in a region with a cold climate, then you should install an exhaust ventilation system. We would not recommend to use it in warm climates, because decreased pressure might draw in hot, moist air. This may result in moisture-related damages.
It is pretty simple and inexpensive to set up an exhaust ventilation system. Usually, a centrally located, single exhaust point serves the purpose.
The only con of this category of ventilation is that they may attract pollutants, along with fresh air. Some examples are radon and molds from a crawlspace, dust particles from the attic, unhealthy fumes from an attached garage, or flue gases from a fireplace, water heater, and furnace. They can also lead to higher energy bills in terms of heating and cooling since they do not absorb moisture from the air that enters the house.
Supply ventilation systems operate by building in pressure inside the building. A fan forces air to enter the interiors while the inside air leaks out via holes in the shell, bath- and range-fan ducts, and intentional vents.
Supply ventilation systems are also quite easy and inexpensive to install. All you need is a fan and duct system that allows air into several rooms at once.
Supply ventilation is better than its exhaust counterparts because it does not allow pollutants to enter the house, thereby, combating indoor air pollution. It also prevents back drafting of combustion gases from fireplaces and appliances.
You can install a supply ventilation system when you reside in hot or mixed climates. They are not advisable to be used in colder climates because warm interior air may leak out through the openings.
Balanced ventilation systems, if properly designed and installed, neither pressurize nor depressurize a house. Rather, they introduce and exhaust approximately equal quantities of fresh outside air and polluted inside air, respectively. A balanced ventilation system usually has two fans and two duct systems. It facilitates good distribution of fresh air by placing supply and exhaust vents in the appropriate places.
A typical balanced ventilation system is designed to supply fresh air to bedrooms and common rooms where people spend the most time. It also exhausts air from rooms where moisture and pollutants are most often generated, such as the kitchen, bathrooms, and the laundry room.
Like both supply and exhaust systems, balanced ventilation systems do not temper or remove moisture from the air before it enters the house.
They do, however, use filters to remove dust and pollen from the outside air before introducing it into the house.
Balanced ventilation systems are appropriate for all climates; however, because they require two duct and fan systems, they are usually more expensive to install and operate than supply or exhaust systems.
Energy recovery ventilation systems usually cost more to install than other ventilation systems. In general, simplicity is key to a cost-effective installation. To save on installation costs, many systems share existing ductwork.
Complex systems are not only more expensive to install, but often they are also more maintenance intensive and consume more electric power. For most houses, attempting to recover all of the energy in the exhaust air will probably not be worth the additional cost. Also, these types of ventilation systems are still not very common. Only some HVAC contractors have enough technical expertise and experience to install them.
In general, you want to have a supply and return duct for each bedroom and for each common living area. Duct runs should be as short and straight as possible. The correct size duct is necessary to minimize pressure drops in the system and thus improve performance. Insulate ducts located in unheated spaces, and seal all joints with duct mastic.
Also, energy recovery ventilation systems operated in cold climates must have devices to help prevent freezing and frost formation. The very cold supply air can cause frost formation in the heat exchanger, which can damage it. Frost buildup also reduces ventilation effectiveness.
In addition, energy recovery ventilation systems need to be cleaned regularly to prevent deterioration of ventilation rates and heat recovery, and to prevent mold and bacteria from forming on heat exchanger surfaces.
The proper choice of a ventilation system depends on the climate of your region, your budget, and specifications. Therefore, choose a set that meets all your needs and keeps your home dry, pleasant, and pollutant-free.