AERCO BMK 3.0 LN Nat. Gas June 2010 - Manual (Page 23)

INSTALLATION
2-11
2.10.11 FAULT RELAY
The fault relay is a single pole double throw
(SPDT) relay having a normally open and
normally closed set of relay contacts that are
rated for 5 amps at 120 VAC and 5 amps at 30
VDC. The relay energizes when any fault
condition occurs and remains energized until the
fault is cleared and the CLEAR button is
depressed. The fault relay connections are
shown in Figure 2-11.
2.11 AUXILIARY RELAY CONTACTS
Each Boiler is equipped with a single pole
double throw (SPDT) relay that is energized
when there is a demand for heat and de-
energized after the demand for heat is satisfied.
The relay is provided for the control of auxiliary
equipment, such as pumps and louvers, or can
be used as a Boiler status indictor (firing or not
firing). Its contacts are rated for 120 VAC @ 5
amps. Refer to Figure 2-11 to locate the AUX
RELAY terminals for wiring connections.
2.12 FLUE GAS VENT INSTALLATION
The minimum allowable vent diameter for a
single Benchmark 3.0 Boiler is 8 inches.
The AERCO Benchmark Venting and
Combustion Air Guide, GF-2050, must be
consulted before any flue gas vent or inlet air
venting is designed or installed. U/L listed,
positive pressure, watertight vent materials as
specified in AERCO’s GF-2050, must be used
for safety and code compliance. Since the unit is
capable of discharging low temperature exhaust
gases, horizontal sections of the flue vent
system must be pitched back to the unit a
minimum of 1/4 inch per foot to avoid
condensate pooling and allow for proper
drainage.
The combined pressure drop of vent and
combustion air systems must not exceed 140
equivalent feet of 8 inch ducting. Fittings as well
as pipe lengths must be calculated as part of the
equivalent length.
For a natural draft installation the draft must not
exceed ±0.25 inch W.C. These factors must be
planned into the vent installation. If the
maximum allowable equivalent lengths of piping
are exceeded, the unit will not operate properly
or reliably.
For Massachusetts boiler installations, the
Heatfab Division of the Selkirk Corporation
provides vent systems which conform to all
applicable requirements for installations within
the Commonwealth of Massachusetts. Contact
information for this supplier is as follows:
Selkirk Corporation
Heatfab Division
130 Industrial Blvd.
Turners Falls, MA 01376
Phone: 1-800-772-0739
www.heat-fab.com
2.13 COMBUSTION AIR
The AERCO Benchmark Venting and Combus-
tion Air Guide, GF-2050 MUST be consulted
before any flue or combustion supply air venting
is designed or implemented. Combustion air
supply is a direct requirement of ANSI 223.1,
NFPA-54, and local codes. These codes should
be consulted before a permanent design is
determined.
The combustion air must be free of chlorine,
halogenated hydrocarbons, or other chemicals
that can become hazardous when used in gas-
fired equipment. Common sources of these
compounds are swimming pools, degreasing
compounds, plastic processing and refrigerants.
Whenever the environment contains these types
of chemicals, combustion air must be supplied
from a clean area outdoors for the protection
and longevity of the equipment.
The AERCO Benchmark 3.0 Boiler is UL listed
for 100% sealed combustion. It can also be
installed using room air, provided there is an
adequate supply. (See paragraph 2.13.3 for
more information concerning sealed combustion
air). If the sealed combustion air option is not
being used, an inlet screen will be attached at
the air inlet on the top of the unit
The more common methods of supplying
combustion air are outlined below. For more
information concerning combustion air, consult
the AERCO Benchmark Venting and
Combustion Air Guide, GF-2050.
2.13.1 Combustion Air From Outside the
Building
Air supplied from outside the building must be
provided through two permanent openings. Each
opening must have a free area of not less than
one square inch for each 4000 BTU/H boiler
input. The free area must take into account
restrictions such as louvers and bird screens.