National Products BW3 - Manual (Page 9)

For boilers with connections to gas vents or chimneys, vent installations shall be in accordance with Part 7 NFGC, Venting of Equipment, in the
United States or Part 7 NSCNGPUC, Venting System and Air Supply for Appliances in Canada, and applicable provisions of local building codes.
Vent connectors serving appliances vented by natural draft shall not be connected into any portion of mechanical draft systems operating under
positive pressure.
PROCEDURE 3—REMOVING EXISTING BOILER FROM COMMON VENTING SYSTEM
When an existing boiler is removed from a common venting system, the common venting system is likely to be too large for proper venting of
the appliances remaining connected to it.
At the time of removal of an existing boiler, the following items shall be followed with each appliance remaining connected to the common venting
system placed in operation, while the other appliances remaining connected to the common venting system are not in operation.
1. Seal any unused openings in the common venting system.
2. 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.
3. 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 appliances 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.
Do not operate a summer exhaust fan. Close fireplace dampers.
4. Place in operation the appliance being inspected. Follow the lighting instructions. Adjust thermostat so appliance will operate continuously.
5. Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of a match or candle, or smoke
from a cigarette, cigar, or pipe.
6. 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.
7. Any improper operation of the common venting system should be corrected so the installation conforms with the NFGC. 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 Part 11 of the NFGC in the United States or Appendix B or the NSCNGPIC in Canada.
NOTE: It is recommended that existing gas vents be checked to be sure they meet local codes.
OPTIONAL HORIZONTAL VENTING WITH POWER VENTER
Horizontal venting with a power venter is an alternate method of sidewall venting. This boiler is A.G.A. and C.G.A. listed for sidewall venting
with standard single wall galvanized or Type-B vent pipe when using 1 of the power venter kits listed in Table 4. These kits are specifically sized
for these boilers.
Some possible reasons for using a power venter for sidewall venting:
1. May be preferred by local codes
2. Need a vent piping run beyond 30 ft (but not more than 50 ft)
Fig. 5—Type-B Gas Vent
A95196
SHEET METAL
FIRESTOP
THE VENT PIPE MUST BE AT
LEAST 2 FT HIGHER THAN
ANY PART OF THE ROOF
WITHIN A 10 FT RADIUS
OF THE VENT.
3' MIN
2' MIN
10'
CHIMNEY
VENT SYSTEM
THIMBLE
CLEANOUT
LINER
Table 4—Boiler and Power Venter
BOILER SIZE (SEC-
TIONS)
FIELD CONTROLS
POWER VENTER KIT
2, 3, 4, 5 SWG-4D
6, 7 SWG-5D
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