Model CFC
ClearFire Commercial Boilers
56
Rev. 05-2012
suppliers, and any local codes having jurisdiction. Refer to vent manufacturer’s
specifications for applicability.
Proper installation of flue gas exhaust venting is critical to efficient and safe
operation of the Clearfire Boiler. The vent should be supported to maintain proper
clearances from combustible materials. Use insulated vent pipe spacers where the
vent passes through combustible roofs and walls.
The design of the stack and breeching must provide the required draft at each boiler
flue gas connection; proper draft is critical to burner performance.
Although constant pressure at the flue gas outlet is not required, it is necessary to
size the breeching and stack to limit flue gas pressure variation. Consideration of
the draft must be given whenever direct vent combustion is utilized and lengthy runs
of breeching are employed. Please note: The allowable pressure range for design of
the stack, breeching and if used, direct vent combustion pipe, is negative 0.25"
W.C. (- 62 Pa) to positive 0.25" W.C. (+62 Pa) for proper combustion and light offs.
Whenever two or more boilers are connected to a common breeching/stack, a draft
control system may be required to ensure proper draft.
Vent Termination
To avoid the possibility of property damage or personal injury, special attention to
the location of the vent termination must be considered.
1. Combustion gases can form a white vapor plume in the winter. The plume could
obstruct a window view if the termination is installed in close proximity to
windows.
2. Prevailing winds could cause freezing of Condensate and water/ice buildup on
building, plants, or roof.
3. The bottom of the vent termination and the air intake shall be located at least
12 inches above grade, including the normal snow line.
4. Non-insulated single-wall metal vent pipe shall not be used outside in cold
climates for venting combustion gases.
5. Through the wall vents for Category II and Category IV appliances shall not
terminate over public walkways or over an area where Condensate or vapor
could create a nuisance or hazard or could be detrimental to the operation of
other equipment.
6. To prevent accidental contact by people or pets, the vent termination shall be
guarded.
7. DO NOT terminate vent in window well, alcove, stairwell or other recessed area,
unless approved by local authority.
8. DO NOT terminate above any door, window, or gravity air intake as Condensate
can freeze causing ice formation.
9. Locate or guard vent to prevent Condensate from damaging exterior finishes.
Use a 2' x 2' rust resistant sheet metal backing plate against brick or masonry
surfaces.
10. Multiple direct stack installations require four feet clearance between the stack
caps, center to center.
U.S. Installations
Refer to the latest edition of the National Fuel Gas Code/NFPA 54. Vent
termination requirements are:
1. Vent must terminate at least four feet below and four feet horizontally or one foot
above any door, window or gravity air inlet to the building.
