Thermo Products MO-425 manual Ii. Installation, Make-Upair, A. Chimney, Proper Chimney Size

All installations and services must be performed by qualified service personnel.

If the "entire" building is unusually tightly constructed and/or has an exhaust fan installed, a low pressure zone could be created within the structure. Air for combustion and draft control operation must be supplied from the outdoors or from spaces freely communicating with the outdoors. Under these conditions, a permanent opening or openings having total free area of not less than 1 square inch per 5,000 BTUH of the total input rating of all the appliances located in the same proximity of the furnace should be provided. These openings must remain free and unobstructed.

Example: 100,000 BTUH input furnace plus a 40,000 BTUH input water heater require an opening or openings totaling 28 square inches of free area.

MAKE-UP AIR:

Today's emphasis on home insulation increases the probability of inadequate air supply to the furnace. Heavy insulation cuts off infiltration of outside air, which previously replaced inside air removed by bathroom, kitchen and laundry vent fans, and air escaping up chimneys. This causes a negative pressure differential within the home that reduces the supply of air available to the furnace for combustion and ventilation.

The Thermo Pride Make-Up-Air Control, installs quickly and easily on any warm air heating system, delivers controlled, fresh air automatically during the winter and a constant supply of clean, fresh air for comfortable summer living. It resolves the negative pressure differential problem.

II. INSTALLATION

A. CHIMNEY:

The furnace must be connected to an adequate chimney or an approved vent in accordance with these instructions. An adequate chimney is one that is sealed and lined with the capability of producing a (-).04" WC flue draft and having the capacity to handle the amount of stack gases that are introduced into it. A chimney with an internal construction of corrosion resistant tile, stainless steel, or some other material that will withstand flue gas temperatures up to 900°F is required.

Qualified service personnel must perform all installations and services.

The following are common chimney requirements necessary for the furnace to operate correctly:

A masonry chimney serving a Thermo Pride oil fired furnace must comply with local codes and NFPA Standard for Chimneys, Fireplaces, Vents, and Solid Fuel Burning Appliances (NFPA211-1996 or latest edition).

1. PROPER CHIMNEY SIZE:

The inside area of the chimney liner should equal, at minimum, the area of the vent pipe exiting the furnace-

EXAMPLE: F x r2 = Area of Pipe (sq. in.)

r= radius of pipe F = 3.1417

Flue Pipe Diameter = 6" [Radius of pipe = ½ diameter of pipe = ½ (6 in.) = 3in.] F x 32 = 28 sq. in.

NOTE: This formula calculates the minimum inside area of the chimney. If more than one appliance vent connector pipe is connected to the chimney, the minimum inside area of the chimney should be equal to the area of the largest vent pipe plus one half the area of any additional vent pipes. If the chimney is too large or condensation has been a problem in the past refer to the NFPA Standard for the Installation of Oil Burning Equipment (NFPA31-1997 or latest edition) Appendix E for proper liner sizing.

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