Benchmark 750-3000 Installation & Startup Manual
SECTION 2
– INSTALLATION
OMM-115_D
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GF-200
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5/9/2019
Technical Support
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2.11.14 Auxiliary Relay Contacts (NC, COM, & NO)
Each unit 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
unit status indictor (firing or not firing). Its contacts are rated for 120 VAC @ 5 amps. Refer to
Figure 2-11 to locate the AUXILIARY RELAY terminals for wiring connections.
2.12 FLUE GAS VENT INSTALLATION
AERCO
’s
Benchmark Venting and Combustion Air Guide,
TAG-0022 (GF-2050) must be
consulted before any flue or combustion air venting is designed or installed. Suitable, U/L
approved, positive pressure, watertight vent materials MUST be used for safety and UL
certification. Because the unit is capable of discharging low temperature exhaust gases,
the
flue must be pitched back towards the unit a minimum of 1/4" per foot (0.64 cm per 0.3 m)
to avoid any condensate pooling and to allow for proper drainage.
While there is a positive flue pressure during operation, the combined pressure drop of vent and
combustion air systems
must not exceed 140 equivalent feet (42.7m)
or 0.8” W.C. (199 Pa)
.
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” W.C. (-62 Pa)
. 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.
2.12.1 MASSACHUSETTS INSTALLATIONS
For Massachusetts installations, the following companies provide vent systems which conform
to all applicable requirements for installations within the Commonwealth of Massachusetts.
Contact information is as follows:
Selkirk Corporation - Heatfab Division
130 Industrial Blvd.
Turners Falls, MA 01376
Phone: 1-800-772-0739
Watertown Supply
33 Grove St.
Watertown, MA 02472
Phone: (617) 924-2840
Glover Sheet Metal, Inc.
44 Riverdale Ave.
Newton, MA 02485
Phone: (617) 527-8178
www.gloversheetmetal.com
Emerson Swan Co
Engineering Products Department
300 Pond St.
Randolph, MA 02368
Phone 781-986-2555
Fax 781-986-2027
www.emersonswan.com
