FIGURE 8.

Chemical Vapor Corrosion

Boiler corrosion and component failure can be caused by the heating and breakdown of airborne chemical vapors. Spray can propellants, cleaning sol­vents, refrigerator and air conditioning refrigerants,­ swimming pool chemicals, calcium and sodium

chloride (water softener salt), waxes, and process chemicals are

typical compounds which are potentially corrosive. These materials are corrosive at very low concentration­ levels with little or no odor to reveal their presence.

Products of this sort should not be stored near the boiler. Also, air which is brought in contact with the boiler should not contain any of these chemicals. If necessary, uncontaminated air should be obtained from remote or outside sources. Failure to observe this requirement will void the warranty.

Installtion Clearances

This boiler MUST NOT be installed on carpeted floors. This boiler is approved for installation on combustible­ flooring in an alcove with

minimum clearances to combustibles of:

4” (102mm) Rear; 0” (0mm) Top and Sides; 6” (152mm) Vent. 2” (51mm)

clearance is allowable from combustible construction for hot water pipes.

Sufficient areashouldbeprovidedatthefrontandrearoftheunitforprop­er servicing. Service clearances of 24” (610mm) in front, rear, top and sides

are recommended. In a utility room installa­tion, the door opening shall be wide enough to allow the boiler to enter or to permit the replacement of another appli­ance such as a boiler.

Leveling

Each unit should be checked after instal­lation­ to be certain that it is level.

If the unit is not level, obtain and insert shims under the feet at the frame base to correct this condition.

Air Requirements

Breathing Hazard - Carbon Monoxide Gas

Install appliance in accordance with the Instruction Manual and NFPA 54 or CAN/CSA-B149.1.

To avoid injury, combustion and ventilation air must be taken from outdoors.

Do not place chemical vapor emitting products near water heater.

Breathing carbon monoxide can cause brain damage or death. Always read and understand instruction manual.

Unconfined Space

In buildings of conventional frame, brick or stone construction, unconfined spaces may provide adequate air for com­bustion.

If the unconfined space is within a building­ of tight construction (buildings­ using the following construction: weather­ stripping,­ heavy insulation, caulking,­ vapor barrier, etc.), air for combus­tion,­

ventilation,­ and draft hood dilu­tion­ must be obtained from outdoors or spaces freely communicating with the outdoors. The installation

instructions for confined­ spaces in tightly constructed­ buildings

must be followed to ensure adequate air supply.

Unusually Tight Construction

In unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue gases. However, in buildings of unusually tight construction (for example, weather stripping, heavily insulated, caulked, vapor barrier, etc.)

additional air must be provided using the methods described in

the Confined Space section that follows.

Confined Space

A Confined Space is one whose volume is less than 50 cubic feet per 1,000 Btu/hr (4.8 cm per kW) of the total input rating of all

appliances installed in the space.

Openings must be installed to provide fresh air for combustion, ventilation and dilution in confined spaces. The required size for

the openings is dependent on the method used to provide fresh

air to the confined space and the total Btu/hr input rating of all

appliances installed in the space.

Direct Vent Appliances

Appliances installed in a Direct Vent configuration that derive all air for combustion from the outdoor atmosphere through sealed intake air piping are not factored in the total appliance input Btu/hr calculations used to determine the size of openings providing fresh air into confined spaces.

EXHAUST FANS

Where exhaust fans are installed, additional air should be provided to replace the exhausted air. When an exhaust fan is installed in

the same space with a water heater, sufficient openings to provide

fresh air must be provided that accommodate the requirements for all appliances in the room and the exhaust fan. Undersized openings will cause air to be drawn into the room through the appliance vent system causing poor combustion. Sooting, serious

damage to the appliance and the risk of fire or explosion may result.

It can also create a risk of asphyxiation.

LOUVERS AND GRILLES

The free areas of the fresh air openings in the instructions that follow do not take in to account the presence of louvers, grilles or screens in the openings.

The required size of openings for combustion, ventilation and dilution air should be based on the “net free area” of each opening. Where the free area through a design of louver or grille or screen is known, it should be used in calculating the size of opening required to provide the free area specified. Where the louver and grille design and free area are not known, it should be assumed that wood louvers will have 25% free area and metal louvers and grilles will have 75% free area. Non motorized louvers and grilles should be fixed in the open position.

Fresh Air Openings for Confined Spaces

The following instructions should be used to calculate the size, number and placement of openings providing fresh air for combustion, ventilation and dilution in confined spaces. The illustrations shown in this section of the manual are a reference

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A.O. Smith VB/VW- 750 Chemical Vapor Corrosion, Installtion Clearances, Leveling, Unconfined Space, Confined Space

VB/VW- 1000, VB/VW- 750 specifications

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