Make Up Air From Attic

Hi everyone i ve visited this site a couple times but this is my first post.

Make up air from attic.

Your kitchen might be choking under the pressure every time an exhaust fan removes air from your house an equal volume of air must enter. The continuous stream of fresh air drawn in by this fan is dumped directly into the attic where it is tempered and preconditioned by mixing with air in the space. The air that enters cracks in a home s envelope to replace air that is exhausted is called makeup air. Connect an outside air duct to the plenum on the furnace if the house has a forced air heating and cooling system.

These are through the wall systems that balance the amount of outgoing air with an equal amount of incoming air. Original installers used pvc to vent the furnace to the roof but combustion air for the furnace is pulled from inside the house. I have a goodman 93 high efficency natural gas furnace located in my single story home in the utility room. In an exhaust based ventilation system the air that is drawn into a space is called make up air.

Incoming air can be heated with electric resistance strips. Makeup combustion air for the water heater is via a floor vent to the crawl space and a ceiling vent to the unheated attic above. Two existing building practices affecting makeup air are causing increasing problems for homeowners. Install a makeup air kit from fantech or electro industries.

Make up air is required to combat negative pressure in a home created by running a large ventilation unit. If there are gas run appliances in the home then a deadly backdraft can occur but that is not the only issue. Then the air is drawn into the open return side of the air handler located just a few feet away from the inlet and distributed via the air handler to the occupied rooms in the. When negative pressure occurs air will be pulled into the structure from somewhere.

In the case of make up air ducts the opening between the attic and the room is not considered a concealed draft opening. The ceiling vent is a 6 inch rigid vertical circular air duct that opens to the attic and extends about 4 feet up from the utility room ceiling. Utility room is not closed off in any way to the rest of the house. Ok to take make up air from an attic but this implementation is not proper nor is it ok to have an opening from the garage into the attic if the ceiling is providing fire separation.

The house is so tight 0 39ach 50 that when the range exhaust fan is operating without the make up duct open there is less than 30 cfm being exhausted. Homes are getting tighter and trendy multiple. But fire blocking for a single family house is defined in the irc section 602. There just isn t enough air leaks in the house to provide the make up air so in order for the exhaust fan to do its job we need to provide a duct for make up air.