through a refrigeration unit unless the unit is specifically approved for such service.
Generally, a six-inch clearance between the air conditioning evaporator coil and the heat exchanger will provide adequate airflow through the evaporator coil.
The blower speed must be checked and adjusted to compensate for the pressure drop caused by the evaporator coil. Refer to Appendix B for recommended wiring and electrical connections of the air conditioning controls.
COMBUSTION AIR
When a furnace is installed in the full basement of a typical frame or brick house, infiltration is normally adequate to provide air for combustion and draft operation. If the furnace is installed in a closet or utility room, two (2) ventilation openings must be provided connecting to a well ventilated space (full basement, living room or other room opening thereto, but not a bedroom or bathroom). One opening shall be located 6" from the top and bottom of the enclosure at the front of the furnace. For furnaces located in buildings of unusually tight construction, such as those with high quality weather stripping, caulking, windows and doors, or storm sashed windows, or where basement windows are well sealed, a permanent opening communicating with a well ventilated attic or with the outdoors shall be provided, using a duct if necessary. Size all of the openings and associated ductwork by the standards provided in the latest Oil Installation Code editions; NFPA 31 in the United States, CAN/CSA B139 in Canada. Take all fuel burning appliances in the area into consideration when calculating combustion and ventilation air requirements.
The Model CAS-2B-90E Furnace Boot manufactured by Field Controls, Inc. may be used with the furnace to obtain combustion air from outdoors. Use of this device does not alter the need for ventilation air; however, it does provide a good source of combustion air and is connected to the oil burner.
CHIMNEY VENTING
The chimney must be sized correctly and be in good repair. If the chimney is oversized, there is a high risk of the flue gases condensing resulting in damage to the chimney and other venting parts. This problem may be corrected by the use of an appropriately sized chimney liner.
If the chimney serves the WML-C furnace only, the vent should be sized at 5-inch minimum. The MPL-B should be 6-inch minimum. The data provided in Table 3 is based on dedicated venting. If the furnace is to be co-vented with other appliances, refer to NFPA 211, Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, NFPA 31, Standard for the Installation of Oil Burning Equipment or CAN/CSA B139, Installation Code For Oil Burning Equipment for correct sizing information.
NOTE: This furnace is approved for use with L-Vent.
NOTE: Maximum temperature for L- Vent is 575°F (300°C).
IMPORTANT: The chimney must be capable of providing sufficient draft at all times for the safe removal of the products of combustion.
The chimney should be tested under “winter” conditions; doors and windows closed, all other fossil fuel burning appliances on, clothes dryer on, bathroom fans on, etc. If the chimney cannot overcome the competition for air, it will be necessary to access the reason for it, and take corrective action. If the chimney is found to be sized correctly and in good repair, it will probably be necessary to re-evaluate the availability of combustion and ventilation air, and take corrective action.
The flue pipe should be as short as possible with horizontal pipes sloping upward toward the chimney at a rate of one-quarter inch to the foot. The flue pipe should not be smaller in cross sectional area than the flue collar on the furnace. The flue pipe should connect to the chimney such that the flue pipe extends into, and terminates flush with the inside surface of the chimney liner. Seal the joint between the pipe and the lining. The chimney outlet should be at least two feet above the highest point of a peaked roof. All unused chimney openings should be closed. Chimneys must conform to local, provincial or state codes, or in the absence of local regulations, to the requirements of the National Building Code.
See Figure 2 and Table 2 for common chimney problems and their remedies.
THE FURNACE MUST BE CONNECTED TO A FLUE HAVING SUFFICIENT DRAFT AT ALL TIMES TO ENSURE SAFE AND PROPER OPERATION OF THE APPLIANCE.
The flue pipe must not be routed through concealed space, because it must be visually checked for signs of deterioration during the annual inspection and servicing. The flue pipe must not pass through any floor or ceiling, but may pass through a wall where suitable fire protection provisions have been installed. In the United States, refer to the latest edition of NFPA 31 for regulations governing the installation of oil burning equipment. In Canada, refer to the latest edition of CAN/CSA B139 for rules governing the installation of oil burning equipment.
NOTE: THE RECOMMENDED FLUE DRAFT PRESSURE IS -0.02 IN. W.C.
(AS MEASURED UPSTREAM OF THE BAROMETRIC DRAFT REGULATOR). SHOWN IN FIGURE 1.
DRAFT REGULATOR CONTROL
This device is used in conjunction with conventional chimney venting. This control (or draft regulator) automatically maintains a constant negative pressure in the furnace to obtain maximum efficiency. It ensures that proper pressures are not exceeded. If the chimney does not develop sufficient draft, the draft control cannot function properly. The draft regulator, must be installed within the same room or enclosure as the furnace, and should not interfere with the combustion air supplied to the burner. The control should be located a minimum of 3 flue pipe diameters from the furnace breeching and installed in accordance to the instructions supplied with the regulator.
