Harsco Industrial C1500H Installation & Owner's Manual page 18

combustion air damper relay will energize and drive the damper open. Once the damper reaches the fully-open
position, the end limit switch makes contact and closes the external interlock circuit allowing the boiler to fire. The
diagram below shows the wiring necessary to install the normally-closed motorized damper.
be negative from the barometric to the vent termination (Category II) at all times to prevent leakage of harmful flue
gases into the room. Leakage of flue gases can cause serious injury or death. Note: this applies to Category II
venting only.
3.5.1.1 Gas Vent Categories
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.
3.5.1.2 Venting Materials for Flue/Exhaust Systems
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The MACH C1500H/C2000H/C2500/C3000/C4000 boilers are dual certified as a Category II and Category IV
appliance, which vents with a temperature that is likely to cause condensation in the vent. Therefore, any venting
system used with the MACH
systems as specified 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.
appliances only. Do not use these venting materials for venting liquid or solid fuel (such as oil, kerosene, 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.
Use caution if installing a barometric damper in the exhaust vent. The vent pressure must
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boiler must comply with the requirements for either Category II or Category IV venting
The venting materials listed below are intended for the venting of gas burning
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MACH Gas Fired Boiler