At the time of removal of an existing boiler, the follow-
ing steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances remain-
ing connected to the common venting system are not
in operation:
31
Fig. 26: Typical Common Venting
Horizontal Through-the-Wall Direct
Venting (Category IV)
Note: Heaters rotated to show venting connections. An extractor is required for this configuration.
Fig. 27: Horizontal Through-the-Wall Venting
Refer to Table F and local codes.
Fig. 28: Horizontal Through-the-Wall Direct Venting
Refer to Table F and local codes.
(a) Seal any unused openings in the common venting
system.
(b) Visually inspect the venting system for proper size
and horizontal pitch and make sure there is no
blockage or restriction, leakage, corrosion and
other deficiencies which could cause an unsafe
condition.
(c) Place in operation the appliance being inspected.
Follow the lighting instructions. Adjust thermostat
so appliance will operate continuously.
NOTE:
For extractor sizing, typical CO
2
levels are
8.5% for natural gas and 9.5% for propane gas and
flue temperatures of less than 220°F.
