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Servicing should only be performed by a Qualied Service Technician
MAKE-UP AIR – DIRECT COMMUNICATION WITH OUTDOORS:
A fresh supply of make-up air for combustion can be supplied to the water heater through make-up air ducts,
which directly communicate with the outdoors. (Not Direct Vent.)
Two openings are required: one within 12 inches (30 cm) of the top of the enclosure and one within
12 inches (30 cm) of the bottom of the enclosure. Each opening must have a free area of not less than
1 square inch per 4,000 BTU/Hr of the total input of all appliances within the enclosure. The lower
opening primarily provides combustion air. The upper opening provides vent dilution air and acts as
a relief opening for flue gases should the vent become obstructed or a downdraft condition occur.
Additionally, when the water heater is installed in a confined space and communicating with the outdoor air,
one permanent opening, beginning within 12 inches (30 cm) of the top of the enclosure, must be permitted
where the equipment has clearances of at least 1 inch (2.5 cm) from the sides and back, and 6 inches
(16 cm) from the front of the appliance. The opening must directly communicate with the outdoors and
must communicate through a vertical or horizontal duct to the outdoors or spaces (crawl or attic) that freely
communicate with the outdoors, and must have a minimum free area of a) 1 square inch per 3,000 BTU/Hr
per kW) of the total input of all equipment located in the enclosure and b) not less than the sum of the
areas of all vent connectors in the confined space.
Corrosion of the flue ways and vent system may occur if air for combustion contains certain chemical vapors.
Such corrosion may result in failure and risk of asphyxiation.
Combustion air that is contaminated can greatly diminish the life span of the water heater and water heater
components such as hot surface igniters and burners. Propellants of aerosol sprays, beauty shop supplies,
water softener chemicals and chemicals used in dry cleaning processes that are present in the combustion,
ventilation or ambient air can cause such damage.
Do not store products of this sort near the water heater. Air which is brought in contact with the water
heater should not contain any of these chemicals. If necessary, uncontaminated air should be obtained from
remote or outdoor sources. The limited warranty is voided when failure of water heater is due to a corrosive
atmosphere. (See limited warranty for complete terms and conditions).