Specifications

Page 6 of 40 12/03/2013
Benchmark Series Boilers
Venting and Combustion Application Guide
GF-2050
TAG-0022_0S
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
The bottom of the vent termination should be at least 12 inches above both finished grade and
any maximum snow accumulation level to avoid blocking the vent or air intake. The vent
termination should be least 3 feet above any forced-air building inlet within 10 feet. Design must
prevent flue gases from recirculating through the boiler air intake.
Vents should not terminate over public walkways or areas where condensate or vapor could
create a nuisance or be detrimental to the operation of regulators, meters or related equipment.
Discharges should not be located in high wind, wind-blocked areas or corners, or be located
directly behind vegetation. Discharges in these locations may cause the flue pressures to
fluctuate and result in flame instability. As a general rule, designs should minimize wind effects.
Wall and roof penetrations should follow all applicable codes and the vent manufacturer's
instructions. Vents should never be installed at less than required clearances to combustible
materials, as enumerated in UL, NFPA, CSA B149.1-10 or local codes "Double-wall" or
'Thimble" assemblies are required when vents penetrate combustible walls or roofs.
Vertical discharges should extend at least 3 feet above the roof through properly flashed
penetrations, and at least 2 feet above any object within a 10-foot horizontal distance.
Vertical and horizontal discharges should be designed to prevent rain from entering the vent.
Large-mesh screens can be applied to protect against the entry of foreign objects but the 'free
area' should be at least twice the flue cross-sectional area.
If the vent system is to be connected to an existing stack, the stack must be UL listed for
Category II, III, and IV appliances (capable of 480°F, positive pressure and condensing flue gas
operation). Masonry stacks must be lined, and the vent penetration must terminate flush with,
and be sealed to, this liner. Vents may enter the stack through the bottom or side. All side
connections must enter at a 45-degree connection in the direction of flow and must enter at
different elevations, with the smallest vent connection at the highest elevation. Benchmark vents
must not be connected to other manufacturer’s equipment.
The exhaust vent must be pitched upward toward the termination by a minimum of ¼ inch per
foot of length. Condensate must flow back to the Benchmark unit freely, without accumulating in
the vent.
1.4 Combustion Air Supply
The Benchmark boilers require the following combustion air volumes when operated at full
capacity.
• BMK 750 165 SCFM
• BMK 1000 200 SCFM
• BMK 1500 325 SCFM
• BMK 2000 500 SCFM
• BMK 2500 600 SCFM
• BMK 3000 700 SCFM
• BMK 6000 1400 SCFM
These flows MUST be accommodated. Air supply is a direct requirement of NFPA, CSA B149.1-
10 (Canada) and local codes that should be consulted for correct design implementation.
In equipment rooms containing other air-consuming equipment ― including air compressors