SUPPLY
RETURN
DUAL AQUASTAT
(#1 SET AT 170F, #2 SET AT 175F)
SINGLE AQUASTAT
(#3 SET AT 180F)
OUTDOOR THERMOSTAT
(SYSTEM STARTER)
H
24V TRANSFORMER
ELECTRONIC
LOW WATER
CUTOFF
MANUAL RESET
HI-LIMIT
SAFETY
HI-LIMIT
CIRCULATOR
NOTE: CONTROLS (THERMOSTATS, LOW WATER
CUT-OFFS, AQUASTATS) ARE RATED AT 8 AMP.-120V,
5.1 AMP.-240V (1/2 HP). WHEN CIRCUIT POWER
EXCEEDS THIS, CONTACTORS MUST BE USED. 24V
TRANSFORMER MUST HAVE 60VA MINIMUM RATING.
OUTDOOR BULB
(LOCATED ON NORTH WALL)
SUNSHIELD
GAS VALVE
FIGURE C2: EXAMPLE OF LEVEL I CONTROL FOR SPACE HEATING ONLY
When outdoor temperature falls below setting of outdoor thermostat, transformer and circulator are energized. All modules will fire until tempera-
ture in return header reaches setting of modulating aquastats. Aquastats will then shut off modules until a point is reached where modules still fir-
ing are just able to satisfy heat load. Example (3-module system), as return temperature rises, dual aquastat "steps-out" module #1 (i.e. at 170F),
then module #2 (i.e., at 175F). Single aquastat "steps out" module #3 at maximum return temperature (i.e., at 180F).
N
115V
L1
L2
B
B
NO C
IN COM COM 24
VAC
HI-LIMIT AQUATAT
RETURN
H2A
115/24V
TRANSFORMER
LOW WATER CUTOFF
GAS VALVE
N
#4
#3
#2
#1
SUPPLY
MANUAL RESET
HI-LIMIT
TO CONTROL
PANEL
SUPPLY WATER
TEMP. SENSOR
NOTE: CONTROLS (THERMOSTATS, LOW WATER CUT-OFFS,
AQUASTATS) ARE RATED AT 8 AMP.-120V, 5.1 AMP.-240V (1/2 HP).
WHEN CIRCUIT POWER EXCEEDS THIS, CONTACTORS MUST BE
USED. 24V TRANSFORMER MUST HAVE 60VA MINIMUM RATING.
AA
HEAT STARTER
240
VAC
COM
120
VAC
Y
TRANSFORMER
AR
RESET
S
STAGE
S
STAGE
240
NC COM NO
NC COM NO
AC
COM 120 NC
C
NO
SENSOR
SUPPLY
SENSOR
D.A.
SENSOR
COM
OUTSIDE AIR SENSOR
SUPPLY WATER SENSOR
OUTSIDE
AIR SENSOR
L1
L2
B
B
N H H
#1
DISPLAY
MODULE
(OPTIONAL)
BOILER
ROOM
SWITCH
H2A
SINGLE POLE
RELAY WITH
115 COIL
MANUAL
RESET
HIGH LIMIT
LOW WATER CUTOFF
TO CIRCULATOR
CONTROL COIL
#2
#3
#4
115V LINES FROM
FUSED DISCONNECTS
POWER DISTRIBUTION WIRING
GATE VALVE (2)
D
DISPLAY
PRESS FOR SETPOINT
180
S
STAGE
NC COM NO
REQUIRED:
AA HEAT STARTER
OR
EQUIV. AUTOMATIC
CONTROL (T6031A)
OR
MANUAL SWITCH
(TO AVOID BOILERS
FIRING WITHOUT
CIRCULATOR
OPERATION)
FIGURE C3: EXAMPLE OF LEVEL II CONTROL FOR SPACE HEATING ONLY
When outdoor temperature falls below setting of heat starter module, transformer and circulator circuits are energized. Reset module regulates
supply water temperature in relation to outdoor temperature. Individual stage modules turn on more boiler modules as the outdoor temperature
falls below their settings.
28
Summary of Contents for MultiTemp MR Series
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