Building materials must not come in contact with combustion products from stack or chimney, due to the degradating properties of flue products.
Flue products must have a minimum clearance of 4 feet (1.22m) horizontally from, and in no case above or below, unless a
CAN/CSA B149.1, Installation Code specifies a 6 foot horizontal vent terminal clearance to gas and electric meters and relief devices (this clearance is specified as 4 feet in the U.S. under the National Fuel Gas Code, ANSI/Z223.1). Therefore instruction, which specifies compliance with the 4 foot clearance, as applies in the U.S. only, and the CAN/CSA B149.1 Installation Code applies in Canada.
1.DRAFT HOOD
The draft hood furnished with this boiler must be installed without alteration. Provision must be made if the boiler is installed in confined space or a small boiler room to accommodate draft hood spillage and avoid risks described above. The upper air opening called for in the AIR REQUIREMENTS section of this manual is for this purpose.
2.VENT CONNECTION
Size and install proper size vent pipe. Do not reduce pipe size to less than that of the draft hood outlet.
Horizontal runs of vent pipe shall be securely supported by adequately placed (approximately every 4 feet or 1 meter), non- combustible hangers and/or slip joints suitable for the weight and design of the materials employed to prevent sagging and to maintain a minimum upward slope of 1/4" (21mm/m) per foot from the boiler to the vent terminals, see Figure 8. Dampers or other obstructions must not be installed in the vent. Be sure that the vent pipe does not extend beyond the inside wall of the chimney.
VENT PIPE INSTALLATION
FIGURE 8.
Where a continuous or intermittent back draft is found to exist the cause must be determined and corrected. A special vent cap may be required. If the back draft cannot be corrected by the normal methods or if a suitable draft cannot be obtained, a blower type flue gas exhauster may be employed to ensure proper venting and correct combustion if permitted by local codes.
WARNING
FAILURE TO CORRECT BACK DRAFTS WILL CAUSE AIR CONTAMINATION AND UNSAFE CONDITIONS.
Vent connectors serving appliances vented by natural draft shall not be connected into any portion of mechanical draft systems operating under positive pressure.
3. CONNECTING BOILER TO A COMMON VENT
Do not connect the boiler to a common vent or chimney with solid fuel burning equipment. This practice is prohibited by many local building codes as is the practice of venting gas fired equipment to the duct work of ventilation systems.
Where a separate vent connection is not available and the vent pipe from the boiler must be connected to a common vent with oil burning equipment, the vent pipe should enter the common vent or chimney at a point ABOVE the flue pipe from the oil fired unit.
Where two or more appliances vent into a common vent connector or manifold, the area of the common vent or vent connector should at least equal the area of the largest vent connector plus 50% of the areas of the additional draft hood outlets.
When removing a boiler from a system with a common vent, use the following steps:
Be sure the other appliances connected to the common vent are not in operation.
Seal any unused openings in the common venting system.
Visually inspect the venting system for proper size and horizontal pitch and determine there is no blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
WARNING
Ensure sufficient supply and ventilation air. Under no circumstances should the equipment room where the boiler is installed ever be under negative pressure. Insufficient air supply can interfere with combustion and ventilation of this boiler resulting in unsafe conditions.
Insofar as is practical, close all building doors and windows and all doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Close fireplace dampers.
Place in operation the appliance being inspected. Follow the lighting instructions. Adjust thermostat so appliance will operate continuously.
Test for spillage at the draft hood relief opening after five minutes of main burner operation. Use the flame of a match or candle.
After it has been determined that each appliance remaining connected to the common venting system properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas burning appliance to their previous conditions of use.
Any improper operation of the common venting system should be corrected so the installation conforms with the current edition of CAN/CSA B149.1 (current edition). When resizing any portion of the common venting system, the common venting system should be resized to approach the minimum size as determined using the appropriate tables in CAN/CSA B149.1.
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