AERCO BMK 3.0 LN Nat. Gas Jan 2011 - Manual (Page 21)

INSTALLATION
2-9
While it is possible to c ontrol a bo iler or boilers
using one of the previously described modes of
operation, it m ay not be the method best suited
for the appl ication. Prior to s electing o ne of
these m odes of oper ation, it is r ecommended
that y ou consult w ith y our local AER CO
representative or the f actory f or the m ode of
operation th at will work bes t with your
application. F or more information on wiring the
4 to 20 mA / 1to 5VDC or the 0 to 20 mA / 0 to 5
VDC, see paragraph 2.9.3.
2.9.5 Combination Mode
NOTE
Only BMS M odel 16 8 c an be ut ilized f or
the Com bination Mode, n ot the B MS II
(Model 5R5-384).
With a Com bination Mode un it, f ield wiring is
between the unit’s I/O Box wiring terminals, the
CCP (Combination Control Panel), and the BMS
Model 1 68 ( Boiler Ma nagement S ystem). The
wiring m ust be ac complished us ing t wisted-
shielded pair wire from 18 to 22 A WG. Polarity
must be m aintained. For further instructions and
wiring di agrams, r efer to the G F-108 Bo iler
Management System Operations Guide and the
CCP-1 data sheet.
2.10 I/O BOX CONNECTIONS
The t ypes of input and output s ignals and
devices to be connected to the I/O Box terminals
shown in F igure 2- 11 a re des cribed i n t he
following paragraphs.
CAUTION
DO NOT make any connections to the
I/O Box t erminals labeled “ NOT
USED”. A ttempting to d o so ma y
cause equipment damage.
2.10.1 OUTDOOR SENSOR IN
An outdoor air temperature sensor (AERCO Part
No. 12 2790) will be r equired pr imarily f or th e
Indoor/Outdoor reset mode of operation. It c an
also be used with another mode if it is desired to
use th e o utdoor s ensor e nable/disable f eature.
This f eature a llows the b oiler to be enabled or
disabled based on the outdoor air temperature.
The f actory def ault f or th e out door s ensor is
DISABLED. T o enable the sensor and/or select
an enable/disable outdoor temperature, see the
Configuration menu in Chapter 3.
The outdoor sensor may be wired up to 200 feet
from the boiler. It is connected to the OUTDOOR
SENSOR IN and SENSOR COMMON terminals
in the I/O Box (see Figures 2-10 and 2-11). Wire
the s ensor us ing a t wisted s hielded pair wire
from 18 to 22 A WG. There is no po larity t o
observe when ter minating th ese wires. T he
shield is to be c onnected only t o t he terminals
labeled SHIELD in t he I/O Box. The sensor end
of the shield must be left free and ungrounded.
When mounting th e s ensor, it m ust be loc ated
on t he N orth s ide of th e bu ilding where an
average outs ide air tem perature is ex pected.
The sensor must be shielded from direct sunlight
as wel l as impingement b y the e lements. If a
shield is us ed, it m ust allo w f or f ree air
circulation.
2.10.2 AIR SENSOR IN
The AIR S ENSOR IN is c onnected t o the AUX
SENSOR IN and SENSOR COMMON terminals
on the I /O boar d. T he AI R SEN SOR m easures
the tem perature of the air inp ut to t he Air/Fuel
Valve. T his te mperature r eading is one of the
components us ed t o c alculate t he r otational
speed of the bl ower us ed in the c ombustion
Calibration process (Chapter 4).
The AUX SENSOR IN terminals can be used to
add a n ad ditional temperature s ensor f or
monitoring pur poses. T his in put is always
enabled a nd is a view-only input th at c an be
seen i n th e O perating M enu. T he s ensor m ust
be wired to the AUX SENSOR IN and SENSOR
COMMON t erminals a nd m ust be s imilar to
AERCO BALCO wire sensor Part No. 12449. A
resistance c hart f or this s ensor is pr ovided in
Appendix C.
2.10.3 ANALOG IN
The ANALO G IN + and – ter minals ar e us ed
when an ex ternal s ignal i s us ed t o dr ive t he
firing r ate ( Direct Dr ive Mode) or c hange th e
setpoint (Remote Setpoint Mode) of the Boiler.
Either a 4 to 20 mA /1 to 5 VDC or a 0 to 20 mA
/ 0 to 5 VDC s ignal m ay be us ed to vary t he
setpoint or firing rate. The factory default setting
is for 4 to 20 mA / 1 to 5 V DC, however this may
be changed to 0 to 20 mA / 0 to 5 VDC using the
Configuration Me nu des cribed i n Cha pter 3. If
voltage r ather t han c urrent is s elected as t he
drive s ignal, a DI P s witch must be s et on t he
PMC Board l ocated i nside th e Co ntrol B ox.
Contact the A ERCO f actory f or inf ormation o n
setting DIP switches.
All of the s upplied s ignals must be floating
(ungrounded) signals. Connections between the
signal s ource and the B oiler’s I/O Box must be
made using twisted shielded pair wire from 18 to