DeDietrich GT 123 A Installation And Maintenance Manual page 22

4. Boiler Venting Gerneral
Caution & Warning:
It is advised and recommended that the heating contractor-professional apply vent materials that are approved and agency listed.
Installation of any venting must follow all local codes in conjunction with vent manufacturer instructions and appliance manufacturer
instructions.
All De Dietrich GT series oil-gas fired cast iron boilers are high performance boilers that could operate under all 4 vent
categories as established by ANSI Z21.13/CSA 4.9 Standard. To assist with application where the vent category is
unknown a graph 'A' has been provided to assist you in determining the vent category and what venting materials would
be acceptable. Although the gas vent categories were developed specifically for gas fired appliances, using this
information is helpful for oil fired boilers. It is very important the venting be selected according to the conditions that the
boiler will operate under, minimum and maximum firing conditions of the boiler must be respected. The venting installed
must comply and be certified to all applicable codes and standard for each jurisdiction.
Gas-Vent Category [4] Definitions:
Cat. I
A Boiler, which operates with a non-positive vent
(breech) pressure and flue gas temperatures which
avoids excessive condensation
chamber and venting.
Cat. II
A Boiler, which operates with a non-positive vent
(breech) pressure and flue gas temperatures that
produce condensation production in the chamber and
venting.
Chart created by Craig Holdforth
6
500
456
412
368
324
280
236
192
148
104
60
22
Venting
production
Gas-Fired Appliance Vent Categorization
[According to ANSI Z21.13/CSA 4.9 Gas Boiler Standard]
7 8 9 10
Category I
Typical Vent Types [A,B,C & L]
Category II
Typical Vent Types
[BH, AL294C®, 304-316L SS]
Negative
Cat. III
A Boiler, which operates with a positive vent (breech)
pressure and flue gas temperatures which avoids
in the excessive condensation production in the chamber and
venting.
Cat. IV
A Boiler, which operates with a positive vent (breech)
pressure and flue gas temperatures that produce
condensation production in the chamber and venting.
Chart A
Carbon Dioxide [CO ] Content %
2
11 12 11 10
Typical Vent Types
[BH, AL294C®, 304-316L SS]
[BH, AL294C®, 304-316L SS]
Chimney-Vent Pressure
[Inches w.c.]
GT 120 A - GT 1200 A
9 8 7
Category III
Category IV
Typical Vent Types
Positive
09/02/08 - 94863361 - 85784009D
6
260
236
211
187
162
138
113
89
64
40
15