The increasing popularity of using commercial grade kitchen equipment that is listed for use in residences is becomming a growing concern. Most contractors do not make allowances for the vast amount of air these systems displace from the home. Equipment manufacturers are telling consumers that "make up air" is not required, which is disturbing and potentially dangerous. I have seen homes with hoods exhausting 1200 to more than 2000 CFM [cubic feet per minute] without any consideration for make up air. Why is that a concern?
For simplicity, let's say a 1000 CFM exhaust hood is used in a home with 4000 sq.ft and 10' ceilings. That equates to 40,000 cu.ft. of space in the home. If you start cooking and let's say it takes you 30 minutes to prepare a meal, the hood is exhausting 30,000 CFM of air from the structure or 3/4 of the air volume! This places the home under an extreme negative pressure. Opening a door going into the home will probably result in the door being ripped from your hand due to the rush of air into the home. Once the system runs for so long, the amount of air it removes will drop since it can not pull that amount of air into the structure.
This has a very negative impact on an energy efficient designed home. If the home has any fossile fuel appliances such as a gas furnace, gas logs or dryer, a wood burning stove or fireplace; you can see the potential hazard from fire or carbon monoxide poisoning.
These items can be used safely if the design is given special consideration. Systems can be designed where you do not even have to condition the "make up air". Make sure to review this carefully when you are bidding a project, protect yourself and your homeowner. They will thank you later. |