Thermostat Connection; Field Wiring - Modine Manufacturing MRL Series Installation And Service Manual

MRL Series

Thermostat Connection

NOTE: Different thermostats operate according to their particular features. Refer to thermostat
specifications for details.
MRL Series heaters may be controlled by a thermostat or switch. The control voltage is 24 VAC (supplied by
internal transformer) and the burner control box is equipped with a 60" black 24 VAC control wire. Do not
supply 120 VAC to the 24 VAC connection.
Figure 3.17 • Field Wiring Diagram - Controlling a single heater with a single control device
Starting Amp Draw: 4.8 Amps
Running Amp Draw: 1.1 Amps
CONTROL DEVICE
TYP. TWO-STAGE T-STAT OR
SWITCH
R
W1
BR
W2
C
Figure 3.18 • Field Wiring Diagram - Controlling multiple heaters with a single control device
Starting Amp Draw: 4.8 Amps
Running Amp Draw: 1.1 Amps
CONTROL DEVICE
TYP. TWO STAGE T-STAT OR
SWITCH
R
W1
W2
C
TRANSFORMER
–
L2
+
L1

Field Wiring:

When controlling multiple heaters with a single control device, one ERK or ERK-HE per heater is required.
1
An external 24 VAC transformer (0.2 Amp) per heater is required (supplied by installer).
2
Maintain electrical polarity when hooking up multiple heaters.
3
Allow heaters to be switched by zones for heating flexibility.
4
Do not attempt to install transformer inside of heater.
5
BL
BK
G/Y
G/Y
NOT REQUIRED
WHEN USING ERK.
BL BR BK
OPTIONAL 24V COMMON
CHECK THERMOSTAT
INSTRUCTIONS TO SEE
IF NEEDED
RELAY BOX
P/N: ERK
(1 PER HEATER)
C W1 W2
3.0 Installation • Thermostat Connection
G/Y
NOT REQUIRED
WHEN USING ERK.
BL BR BK
RELAY BOX
P/N: ERK
(1 PER HEATER)
C W1 W2
27
• Thermostat Location
G/Y
NOT REQUIRED
WHEN USING ERK.
BL BR BK
RELAY BOX
P/N: ERK
(1 PER HEATER)
C W1 W2