Benchmark 2.0 LN Installation, Operation & Maintenance Manual
CHAPTER 2 – INSTALLATION
OMM-0046_0J
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
29
of
168
GF-123
Ph.: 800-526-0288
06/18/2015
NOTE
Both the Delayed Interlock and Remote Interlock MUST be in the closed
position to allow the unit to fire.
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
2.10.13. 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.
