Bryan Boilers AB Series, Installation, Operation & Service Manual

FIG. 1.8.6D: SUGGESTED BAFFLE 

DIMENSIONS 

Fig. 1.8.6C: BAROMETRIC CONTROL WITH BAFFLE 

FOR CONTROL OF EXCESSIVE DRAFT

1.8.7 ACCEPTABLE VENT TYPES

 
TYPE B GAS VENTS 
Type B gas vents may be used with listed water 
boilers and low pressure (15 psig) steam boilers 
when provided with a factory supplied draft 
diverter. Type B gas vents may also be used 
(subject to local approvals) with UL listed and 
labelled, atmospheric gas-fired CL series water 
boilers and low pressure steam boilers and K-
series water boilers when equipped with a 
correctly installed barometric draft control. Type B 
gas vents may not be used on high pressure 
steam boilers (over 15 psig) or any other Bryan 
boilers not specified above. Type B gas vents 
should preferably bear the U.L. label. Installation 
of these vents must comply with the vent listing, 
with the vent manufacturer's instructions and with 
complete adherence to the codes and clearances 
as outlined previously. 
 
SINGLE-WALL METAL PIPE 
Single-wall metal pipe must be of galvanized 
sheet or other approved noncombustible 
corrosion resistant material, with minimum 
thickness per Table 1.8.7, from the National Fuel 
Gas Code. Single-wall metal pipe should be 
insulated to prevent excessive heat in the boiler 
room and to avoid ignition and spillage problems 
as well as corrosion from excessive 
condensation. 
 
MASONRY, METAL AND FACTORY BUILT 
CHIMNEYS 
Installation of factory built vents and chimneys 
must comply with the vent listing, with the vent  

 
manufacturer's instructions and with adherence to 
the codes and clearances as outlined herein. 
Masonry or metal chimneys must be built and 
installed in accordance with nationally recognized  
building codes or standards. 
MASONRY CHIMNEYS FOR RESIDENTIAL 
APPLICATIONS MUST BE LINED WITH FIRE-
CLAY FLUE LINING (KX C315) OR THE 
EQUIVALENT WITH THICKNESS NOT LESS 
THAN 5/16 INCH OR WITH A LINER OF OTHER 
APPROVED MATERIAL THAT WILL RESIST 
CORROSION, SOFTENING OR CRACKING 
FROM FLUE GASES AT TEMPERATURES UP 
TO 1800 F. 
EXISTING CHIMNEYS SHOULD BE 
INSPECTED FOR UNSAFE CONDITIONS, 
SUCH AS DETERIORATED MASONRY AND 
EXCESSIVE SOOT OR OTHER BLOCKAGE OR 
POTENTIAL BLOCKAGE. SEE ALSO SECTION 
1.8.9. 
 
EXISTING CHIMNEYS MUST BE PROPERLY 
SIZED FOR THE FLUE GAS LOADING TO BE 
USED. THAT IS, IF AN EXISTING CHIMNEY IS 
USED FOR A SMALLER TOTAL INPUT THAN 
ITS ORIGINAL DESIGN, A LINER OR VENT IS 
REQUIRED. THE USE OF A PROPERLY SIZED 
GAS VENT OR LINER WILL PREVENT 
DETERIORATION OF THE CHIMNEY DUE TO 
THE EXCESSIVE CONDENSATION WHICH 
RESULTS ON OVERSIZED SYSTEMS.