Why Is Make-Up Air Important?
Modern homes are equipped with several appliances that, when in use, exhaust air to the outside, including clothes dryers, water heaters, gas stoves, HVAC systems, and fireplaces. Proper ventilation is critical, especially in the kitchen, where gas appliances can produce fumes, including carbon monoxide, from incomplete combustion. To prevent these harmful byproducts from transferring into the living space, kitchen ventilation hoods play a vital role in effectively routing excessive heat and gases to the outside.
However, expelling air from the kitchen's exhaust hood can create negative pressure in the home, especially if the exhausted air is not replaced with fresh air. Negative pressure can lead to several problems, including backdrafting, increased energy consumption, and moisture issues. In the presence of a fireplace, negative pressure could cause outside air to be drawn down the chimney, bringing smoke into the home with it, contributing to carbon dioxide levels in the space. To mitigate these challenges, it's essential to have a make-up air system that works in conjunction with the exhaust system to bring fresh, outside air back into the space, creating what is known as a balanced make-up air system.
Problems Associated With Negative Pressure In The Home
- Backdrafting: This occurs when combustion gases from appliances are pulled back into the home through the exhaust vent instead of being vented to the outside, potentially causing health hazards.
- Increased Energy Consumption: To balance the pressure, outdoor air may enter the home through the exhaust vent, similar to opening a window or door. This unconditioned, humid outside air forces your heating or cooling systems to work harder to maintain the desired indoor temperature. This places a strain on the equipment and is not very energy efficient.
- Moisture: Unfiltered air often carries moisture, leading to higher humidity levels that can promote mold growth and cause structural damage over time.
- Pests and bugs: Negative pressure can draw in insects and pests from outside, potentially leading to an infestation.
- Dust and allergens: Negative pressure can draw in unfiltered air from outdoors or spaces like attics and crawlspaces, which can increase the amount of dust and other allergens in the home.
Several factors contribute to modern homes needing the installation of a make-up air ventilation system:
- Today’s larger cooktops and professional-style ranges require powerful range hoods for effective ventilation. These units can exhaust over 1200 CFM, which means an equivalent volume of air must be brought back into the home to prevent a pressure imbalance.
- Modern construction standards of airtight homes limit any natural air seepage. For instance, homes with spray foam insulation will need a make-up air system in place.
- Multiple exhaust fans running within the home lead to unbalanced pressure in the living space. Even smaller fans running simultaneously or a large, open fireplace can complicate proper ventilation.
A balanced make-up air system not only enhances appliance performance — it maintains harmony between intake and exhausted air and provides peace of mind. Understanding the effects of negative pressure in the home and taking steps towards achieving a balanced airflow level is a vital step towards a healthier and more sustainable home.
With FreshVent, breathe easier today for a healthier tomorrow.