P-K Storm
TM
Gas Fired Boiler
Technical Service 1.877.728.5351
Revised: June 26, 2020
Released: June 26, 2020
©
Patterson-Kelley 2020
All Rights Reserved.
2691000273 P-K Storm ST2500-ST4000
Installation and Owners Manual Rev A.docx
Page 7
Category II/IV Flue Gas Exhaust Vent Planning
Several codes and standards have categorized appliances in accordance with the flue gas temperature
and pressure produced by the appliance. The applicable categories are defined as follows:
•
Category II:
An appliance that operates with a non-positive vent static pressure and with a vent
temperature that may cause excessive condensate production in the vent.
•
Category IV:
An appliance that operates with a positive vent static pressure and with a vent
temperature that may cause excessive condensate production in the vent.
•
Direct Vent:
An appliance that is constructed and installed so that all air for combustion is
derived directly from outdoors and all flue gases are discharged to the outdoors.
All P-K STORM
™
boilers are dual-certified as
Category II or IV
appliances,
as defined in ANSI
Z21.13/CSA 4.9, latest edition. The P-K STORM
™
series boilers are capable of operating with slightly
negative to slightly positive exhaust pressure. It is critical to ensure the flue vent material is certified for
Category II or IV
operation.
N
OTE
:
For
Category II
installations, ensure the flue venting system is designed to maintain a
slightly negative exhaust pressure
between -
0.01” W.C. and -0.05” W.C.
N
OTE
:
For
Category IV
installations, ensure the flue venting system is designed to maintain a
slightly positive exhaust pressure which
MUST
BE
in the following ranges:
•
+0.01” W.C. and +0.22” W.C. (Direct Vent / Sealed Combustion)
•
+0.01” W.C. and +0.4” W.C. (Exhaust Only)
The vent material to be used for US and Canada is listed in the Table of Acceptable Materials for
Venting Systems located in
Vent installations shall be in accordance with NFPA 54/ANSI Z223.1, the National Fuel Gas Code, or
CAN/CSA-B149.1, the Natural Gas and Propane Installation Code, or applicable provisions of the local
building codes.
Vent Sizing for Category II / IV Operation
The vent must be sized in accordance with the
ASHRAE
Systems and Equipment handbook (Chapter
30) or according to the vent manufacturer
’s recommendations. When using manufactured venting
systems, consult your vent supplier for correct sizing and structural support requirements.
P-K STORM
™
Boiler Model
Draft
Stack Temperature
CO
2
Natural Gas
ST-2500, ST-3000,
ST-3500, ST-4000
Category II
-
0.01” to -0.05” W.C.
220 °F (gross)
8.75%
ST-2500, ST-3000,
ST-3500, ST-4000
Category IV
(Sealed Combustion)
+0.01” to +0.22” W.C.
220 °F (gross)
8.75%
ST-2500, ST-3000,
ST-3500, ST-4000
Category IV
(Exhaust Only)
+0.01” to +0.4” W.C.
220 °F (gross)
8.75%
