Benchmark Series Pre-Installation Venting & Combustion Air
TAG-0022_0Z AERCO International, Inc. •100 Oritani Dr. •Blauvelt, New York 10913 Page 3of 51
GF-2050 Phone: 800-526-0288 9/14/2018
1. General
The AERCO Benchmark gas-fired boiler is a high efficiency, forced draft, hydronic-heating unit
with unique venting capabilities. All Benchmark venting options (which include horizontal and
vertical discharges, direct vent, and manifolded vent breeching), typically exceed the
capabilities of competing combustion equipment. These and other features enable Benchmark
boilers to provide extremely high thermal efficiencies and optimum temperature control under
widely varying conditions. It is therefore critical that the flue gas vent and combustion air
system be designed to maintain these objectives.
Benchmark’s high efficiency is achieved through air/fuel modulation and the release of energy
from the moisture condensing in the combustion products. Because condensation can occur
in the exhaust vent system, means must be provided to remove the moisture accumulation.
Each Benchmark model is fitted with a condensate removal trap, as indicated in Figures 1a –
1d, which illustrate the air inlet, vent connections and condensate removal connections for the
BMK 750 (0.75 MMBTU), BMK 1000 (1.0 MMBTU), BMK 1500 (1.5 MMBTU), BMK 2000
(2.0 MMBTU), BMK 2500 (2.5 MMBTU), BMK 3000 (3.0 MMBTU), BMK 5000 (5.0 MMBTU)
and BMK 6000 (6.0 MMBTU) models.
The design guidelines in this bulletin provide broad latitude while meeting the objectives of
safety, longevity and optimum performance.
2. Approved Vent Materials
The Benchmark boiler is a Category II and IV appliance, which requires special attention to
exhaust venting and combustion air details. The exhaust vent MUST be UL listed for use with
Category II and IV appliances. The following materials are allowed:
•BMK 1500 to BMK 6000 boilers can use polypropylene, AL29-4C, and other stainless
steel* vent venting materials. PVC and CPVC are NOT allowed.
•BMK 750 and BMK 1000 boilers can use PVC, CPVC, polypropylene, AL29-4C, and
other stainless steel* vent materials. This is due to the smaller size producing lower
exhaust operating temperatures.
* NOTICE: UL1738 listed material is a minimum requirement for stainless steel vent to be used
with AERCO Benchmark boilers.
DISCLAIMER: It is the responsibility of the design engineer and installing contractor to ensure
all vent system designs and installations follow industry best practices with proper pitch,
support, and drainage to prevent failure. While UL1738 is the industry standard guideline for
venting, it is highly recommended that exhaust vent passing through confined or enclosed
horizontal building spaces be made of AL29-4C as the most corrosion resistant vent material
currently available.
Flue System Requirements – Minimum Thickness for AL29-4C
Diameter Wall Thickness Diameter Wall Thickness Diameter Wall Thickness
3" (7.6 cm) 0.015" (0.38 mm) 9" (22.9 cm) 0.020" (0.51 mm) 20" (50.8 cm) 0.024" (0.61 mm)
4" (10.2 cm) 0.015" (0.38 mm) 10" (25.4 cm) 0.020" (0.51 mm)
22" (55.9 cm) 0.024" (0.61 mm)
5" (12.7 cm) 0.015" (0.38 mm) 12" (30.5 cm) 0.020" (0.51 mm)
24" (61.0 cm) 0.024" (0.61 mm)
6" (15.2 cm) 0.015" (0.38 mm) 14" (35.6 cm) 0.020" (0.51 mm)
26" (66.0 cm) 0.034" (0.86 mm)
7" (17.8 cm) 0.015" (0.38 mm) 16" (40.6 cm) 0.020" (0.51 mm)
28" (71.1 cm) 0.034" (0.86 mm)
8" (20.3 cm) 0.015" (0.38 mm) 18" (45.7 cm) 0.024" (0.61 mm) 30" (76.2 cm) 0.034" (0.86 mm)
