MFC Series Boiler Vent and Combustion Air Guide
TAG-0080_OG
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GF-148-V
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3/29/2023
Technical Support
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(800) 526-0288
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1.
General
The AERCO MFC gas-fired
or fuel oil-fired (backup)
boiler is a high efficiency, forced draft,
hydronic-heating unit with unique venting capabilities. All MFC 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 MFC
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.
MFC
’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 MFC
model is fitted with a condensate removal trap, as indicated in Figure 1, which illustrates the
vent connection and condensate removal connection for the MFC 3000, MFC 4000, MFC 5000,
MFC 6000, MFC 8000, and MFC 10000 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 MFC boiler is a Category II, III, 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:
The MFC 3000, 4000, 5000, 6000, 8000, and 10000 boilers can use only AL29-4C venting
materials.
Polypropylene,
PVC, and CPVC
are NOT allowed
.
TABLE 1: Flue System Requirements
– Minimum Thickness for AL29-4C
DIAMETER
WALL
THICKNESS
DIAM.
WALL
THICKNESS
DIAMETER
WALL
THICKNESS
3"
0.015"
9"
0.020"
20"
0.024"
4"
0.015"
10"
0.020"
22"
0.024"
5"
0.015"
12"
0.020"
24"
0.024"
6"
0.015"
14"
0.020"
26"
0.034"
7"
0.015"
16"
0.020"
28"
0.034"
8"
0.015"
18"
0.024"
30"
0.034"
Proper clearances to combustibles must be maintained per UL and the vent manufacturer
requirements. The UL, National Fuel Gas Code (ANSI Z223.1/ NFPA54)
1
, NFPA 31 Standard for
the Installation of Oil-Burning Equipment,
and CSA B149.1-10 guidelines are often the basis for state
and local codes. AERCO's recommendations follow the guidelines of these agencies, unless
more stringent codes govern the installation site. The venting and combustion air systems must
meet all applicable code requirements. AERCO will not be responsible for failure of the system
design to meet code requirements.
All Canada installations must comply with CSA B149.1 installation code.
MFC Series boilers have the capability to condense on #2 fuel oil if the fuel oil has a low sulfur
content (<15 ppm) and return temperatures are no less than 140 degrees Fahrenheit. For
applications which shall take advantage of this capability, please be sure to utilize the appropriate
venting specified above that has been approved for oil fired equipment and condensing on fuel
oil.
