Aiko CTH3-80, CTH3-150, CTH3-200, CTH3-115 service manual Analog Control Signal Wiring Diagram

SECTION 10: WIRING

For 4-20mA control of the heater(s) firing rate, the following control conditions apply:

ON/OFF relay at the external controller or BMS must be wired to R and W terminals on the heater control board to turn the heater ON and OFF.

(Open Circuit = OFF, Closed Circuit = ON). Minimum rated input at 1% of signal (0-4 mA). Full rated input at 90% of signal (18 mA). Input varies linearly between 4 mA and 18 mA.

BMS controllers often offer PID loop control that can optimize output signal and rate of change of the output signal. Common analog application is defined as follows:

1.BMS sensors that monitor zone air

temperatures are located in the heating space.

FIGURE 27: Analog Control Signal Wiring Diagram

2.Based on sensed temperatures, the BMS will

output an analog signal for the desired heater(s) firing rate.

3.As heater(s) receive the analog signal from the BMS, the heater(s) modulate to the correspond- ing firing rate.

4.As sensed air temperature rises closer to the desired temperature setpoint, the BMS will reduce the output signal, in turn reducing heater firing rate.

5.Upon satisfying temperature setpoint, the BMS will either:

a.Turn off the heater.

b.Reduce the signal so that the minimum heater firing rate is maintained until the sensed temperature rises above the setpoint to a cut-off limit temperature when the BMS turns off the heater.

ON/OFF SWITCH	CENTRAL HEATER CONTROL
REQUIRED
	*OPTIONAL
	SWITCH
	THERMOSTAT
	T24
	R
	T25
	W

SATELLITE HEATER CONTROL

THERMOSTAT

T24

R

T25

W

+	T26	INPUT + -		ANALOG
	T27
-
				THERMISTOR
REMOTE ANALOG	T13
CONTROL
SIGNAL FROM SEPARATE
CONTROLLER	T14
0-10Vdc OR 4-20mA		GN
		D					ANALOG INPUT CONTROL IS
	T15
		BAR	SLIDE				USED TO SELECT ANALOG
							SIGNAL TYPE 0-10Vdc OR 4-20mA
	T16
		GN					(4-20mA POSITION SHOWN).
		D
	T17
		HIGH
	T18	WIPER		EXT. POT
					J9
	T19	GN
		D
	T28
		+		FIRING
		RATE IN				J10 JUMPER POSITION
	T29
						SHOWS "CENTRAL"
		-
						DESIGNATION AND

T26

T27

T13

T14

T15

T16

T17

T18

T19

T28

T29

INPUT + -		ANALOG
GN		THERMISTOR
D
BAR	SLIDE
GN
D
HIGH
WIPER		EXT. POT
GN
D
+		FIRING
IN	RATE
-

J9

FOR SATELITTE

CONTROLLERS, J9 JUMPER CAN BE LEFT IN ORIGINAL POSITION REGARDLESS OF CONTROL METHOD.

	T30						"ANALOG" CONTROL METHOD.
		+	RATE	FIRING
		OUT				A B
	T31
		-
					J10
MODULATION CONTROL WIRING
TO SATELLITE HEATERS

T30				J10 JUMPER POSITION
	+	FIRING		SHOWS "SATELLITE" DESIGNATION.
	RATE OUT		A B
T31
	-

J10

MODULATION CONTROL WIRING

TO ADDITIONAL SATELLITE

HEATER CONTROL TERMINALS

T28 and T29.

*Separate on/off switch is optional for "satellite" heaters (install at user level). On/Off switch is used to disable heater operation or reset a heater that is in "lockout" mode. If on/off switch is not desired, leave jumper wire between R and W terminals in place.

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