MODU-FIRE® Forced Draft Gas-Fired Boiler
13
For correct installation of vent system, read all of these instructions and re-
fer to vent manufacturer’s instructions.
Failure to use a proper vent system (types and materials), as described in this manual will void the
boiler warranty and may result in rapid deterioration of the venting system, creating a health or life
safety hazard.
Faulty vent installation can allow toxic fumes to be released into living areas. This may cause proper-
ty damage, serious bodily injury or death.
3.5.1.1 Gas Vent Categories
Several codes and standards have categorized appliances in accordance with the flue gas temperature and pres-
sure produced by the appliance. Categories are defined as follows:
•
Category I
An appliance that operates with a non-positive vent static pressure and with a vent tempera-
ture that avoids excessive condensate production in the vent.
•
Category II
An appliance that operates with a non-positive vent static pressure and with a vent tempera-
ture that may cause excessive condensate production in the vent.
•
Category III
An appliance that operates with a positive vent static pressure and with a vent temperature
that avoids 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.
3.5.1.2 Venting Materials for Flue/Exhaust Systems
MODU-FIRE® Forced Draft boilers are Category IV appliances, which vent with a positive exhaust pressure and
with a temperature that is likely to cause condensation in the vent. Therefore, any venting system used with the
MODU-FIRE® Forced Draft boiler must comply with the requirements for Category IV venting systems as speci-
fied in the latest edition of NFPA 54/ANSI Z223.1 in the US or the latest edition of CAN/CSA B-149.1 in Canada.
The venting materials listed below are intended for the venting of gas burn-
ing appliances only. Do not use these venting materials for venting liquid or solid fuel (such as oil, ke-
rosene, wood or coal) appliances.
Maintain clearances to combustibles as listed in the vent manufacturer’s installation instructions or as
set forth in the codes and standards listed in this section.
Do not use these vent pipes for incinerators of any sort.
3.5.2 Combustion Air
Combustion air must be free from dust, lint, etc. The presence of such materials in the air supplied to the burner
could cause nuisance "Low Air" shutdowns or premature burner failure. The boiler should not be operated during
construction while the possibility of drywall dust, demolition dust, etc. exists.
The combustion air supply must be completely free of chemical fumes which may be corrosive when burned in the
boiler. Common chemicals which must be avoided are fluorocarbons and other halogenated compounds, most
commonly present as refrigerants or solvents, such as freon, trichloroethylene, perchlorethylene, chlorine, etc.