AERCO BMK 2.0 LN Natural Gas (SN G-11-1861 and above) - Manual (Page 29)

GF-123
Benchmark 2.0LN Low NOx Boiler
Chapter 2
OMM-0046_0E Installation, Operation and Maintenance Manual Installation
PR1 08/20/12 AERCO International Inc.● 100 Oritani Dr. ● Blauvelt, NY 10913. ● Ph: 800-526-0288 Page 29 of 170
2.10.11.1 REMOTE INTERLOCK IN (10)
The remote interlock circuit is provided to remotely start (enable) and stop (disable) the Boiler, if
desired. The circuit is labeled REMOTE INTL’K IN and is located inside the I/O Box on the front
panel. The circuit is 24 VAC and is factory pre-wired in the closed (jumpered) position.
2.10.11.2 DELAYED INTERLOCK IN
(12)
The delayed interlock is typically used in conjunction with the auxiliary relay described in
paragraph 2.11. This interlock circuit is located in the purge section of the start string. It can be
connected to the proving device (end switch, flow switch etc.) of an auxiliary piece of equipment
started by the Boiler’s auxiliary relay. The delayed interlock must be closed for the boiler to fire.
If the delayed interlock is connected to a proving device that requires time to close (make), a
time delay (Aux Start On Dly) that holds the start sequence of the boiler long enough for a
proving switch to make can be programmed. Should the proving switch not prove within the
programmed time frame, the boiler will shut down. The Aux Start On Dly can be programmed
from 0 to 120 seconds. This option is locate in the Configuration Menu (Chapter 3, Table 3-4).
2.10.12 FAULT RELAY
(13)
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 2-10.
2.10.13 AUXILIARY RELAY CONTACTS
(14)
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 2-10 to locate the AUX RELAY terminals for wiring connections.
2.11 FLUE GAS VENT INSTALLATION
The minimum allowable vent diameter for a single Benchmark 2.0LN 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 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 are as follows: