exaust gas vent system

combustionairrequirement.htm
Combustion circulated air review: For proper combustion, all fossil fuel burning appliances must have a sufficient supply of oxygen. Insufficient oxygen may lead to carbon monoxide accumulation within the building. There are formulas, associated with the appliance btu rating, for determining the necessary size of combustion air inlets or grilles. These formulas are helpful and necessary for new installations. In older installations the btu rating of the appliance may not be readily available. When combustion air is taken from inside the building care must be exercised that there will always be enough oxygen left for the human occupants. The following are partial formulas to follow as set forth by building codes which typically are acceptable nationwide. Inside air (or that air taken from inside a building) shall be available for each fuel-burning appliance at a rate of 40 cubic feet of room air per 1000 btu/ hr input rating. In buildings of tight construction (most late model buildings) where the air exchange rate is less than .5 air changes per hour, additional air is required to be provided. When the room in which the appliance is located does not meet the criterion specified above then openings to adjacent spaces must be provided (vents, grilles, or louvered doors). Two openings shall be provided, one near the top of the room and one near the bottom, to help facilitate circulation of the required combustion air. Each opening shall have an unobstructed area equal to a minimum of 1 square inch per 2000 btu (british thermal unit) per hour input rating of all appliances installed in the space, but not less than 100 square inches. Compensate for screens and louvers on grilles when Calculating the square inch value of an opening. Combustion air can be provided by mechanical ventilating systems but the system must Be interconnected to the appliance to assure that combustion air is provided when the appliance is operating. Combustion air may be taken from ventilated attics and crawl spaces and of course, from the outside in general. If the opening is horizontal the formula is 1 square inch per 2000 btu input rating. Vertical openings can be sized at 1 square inch per 4000 btu input rating. Usually it is a simple task to provide combustion air for an appliance. The above calculations/formulas are best discussed with the inspector or a heating contractor before deciding on where to cut a hole for a vent installation. If you do it yourself, be sure to buy the grilles first so you have something to trace around for determining exact hole size. Forced air furnaces need combustion air to facilitate the combustion process which provides heat to the circulated air. The circulated air is returned to the heater through the return air grille. It is important that the return air grill and the heater flame, or any other open flame such as a water heater, be at least ten feet apart, with the exception that the two may be closer if they are separated by a sealed door. The inspector may enter this item if the door (which is usually on the heater closet) is not sufficiently sealed, has vents cut into it, or if there is no such door and the return air grill is within 10 feet. There are many other circumstances whereby circulated air and combustion air may be interconnected. One example: the bottom of the heater is not sealed (caulked) to the platform it sits on and the circulated air is drawn through the bottom side of the heater (as opposed to the top some are reversed). The platform itself may be cracked, damaged or holed or may be constructed with planks not sealed tightly together. Another example: the return air duct is separated from the heater or plenum and draws air into the ducting from around the heater. Since this situation can be life threatening it is recommended that you contact a heating contractor for assistance with corrections.

Electric air conditioners gas heater and electric air conditioner Dual-pack or gas pack A-C condenser and evaporator separate together: Water cooled condenser: 

The above information was provided by TWI Systems Copyright 1995-2007 1-800-553-5660. TWI is a fantastic company to deal with!

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This file was last updated on Saturday, 13-Sep-2008 00:08:27 EDT * Copyright © 2008 All rights reserved by: Accurate Inspections, Inc. A New Jersey home inspection firm providing New Jersey Certified Home Inspections in NJ, by New Jersey Licensed home inspectors. Inspector of record Michael Del Greco, New Jersey home inspectors License GI 0121.

exaust gas vent system