What is Make-Up Air Ventilation?
/If you are embarking on a kitchen remodel, you may be focused on selecting kitchen cabinets, tile, and countertops. Maybe a new, larger cooktop and range hood are on your list of must have items too. If you are planning to upgrade your kitchen, make sure you understand what is required for kitchen ventilation, and for “make-up air” ventilation. Read on to learn more.
Why is make-up air important in your kitchen design?
Modern homes have a number of appliances that require air to be exhausted out of the house, such as a clothes dryer, hot water heaters, gas cooking appliance, HVAC heaters, or fireplace. Proper ventilation is especially important in the kitchen, particularly with gas appliances, to evacuate cooking fumes and carbon monoxide from the kitchen. Kitchen ventilation hoods are essential to help in removing the fumes and carbon monoxide.
New building codes require what is called “make-up air” to be installed when a kitchen ventilation hood exceeds 400 CFM (cubic feet of air per minute). Many gas range and cooktop manufacturers recommend well over 400 CFMs for a ventilation hood especially when you exceed 4 burners on your appliance. So, if your ventilator above your gas range or gas cooktop is over 400 CFM, you need “make-up air”, which means you must bring outside air back into the home to restore the inside air pressure balance.
Why is it important?
If make-up air is not addressed properly, this could lead to an increase in carbon monoxide levels in your living space. How does this happen? If you do not set up a proper system for this make-up air, then when you turn on your ventilator above your hood, air could be drawn down a fireplace chimney causing smoke to enter the house. Even worse, the negative pressure could cause the air to be drawn down a gas hot water heater exhaust vent or even your gas whole house heater vent. When this happens, dangerous carbon monoxide is now entering your living space.
How to prevent this?
When installing a kitchen ventilator larger than 400CFM, there must be air supplied directly into the kitchen area. Here is an example: if a range manufacturer recommends 150CFM per burner, and you purchased a 6-burner range, then you would require an 800 CFM hood vent. 800 CFM would require a minimum vent size of 7” but most professionals would use an 8” or 10” vent to increase the efficiency of the hood vent. So, if you use an 8” duct above your range, then you need to bring in a minimum of 8” of “make-up air”.
How does make-up air work?
There is a hole cut in the exterior of your house and the 8” duct work is run directly into the kitchen design area preferably within 10 feet of the range hood. An electronic damper is installer inside the vent. The damper is connected directly to the switch on your range hood so when you turn on the hood, a gate opens inside of the duct allowing air to flow from outside into your kitchen. This provides the ”make-up air” that balances the air pressure inside your house.
What makes today’s homes more susceptible?
There are several factors that make modern homes more susceptible to issues with ventilation, and therefore require a make-up air ventilation system.
Larger cooktops and ranges, especially today’s professional style ranges, require a much more powerful range hood to properly ventilate when cooking. The big ones can draw out 1200 CFM or more, meaning that much more air must be recirculated back into the home to avoid depressurizing your space.
House construction is much tighter, so there are fewer places for opportunistic air to flow into the home. For example, homes with spray foam insulation definitely require a make-up air system.
You may be more likely in today’s home to have more places where air is exhausted out of the house, e.g., multiple bathroom fans, a clothes dryer, fireplaces, and kitchen range hood or in a very large kitchen design more than one range hood. Even if you do not have a large range hood, running several smaller fans at once or having a large, open fireplace can make proper ventilation an issue.
All these factors mean that planning for make-up air ventilation is more important than ever.
How do you address this issue?
If you notice issues in your home, like bad odors, kitchen exhaust not performing well, grease build up, or difficulty regulating your home’s temperature, it may be time to investigate your home’s ventilation systems. Contact a qualified professional to review your situation and see what remedies are required.
If you are embarking on a kitchen remodel, particularly if you plan to upgrade your cooking appliances (and therefore, perhaps your range hood), discuss make-up air ventilation with your kitchen design professional. An experienced kitchen remodeling firm should be able to advise you on what is required and include this in your kitchen design plans.
Getting ready to upgrade your kitchen and want to learn more about make-up air ventilation? Contact us on 215-968-5300 to discuss your requirements with one of our kitchen design experts.
