Honeywell Heating System L8124A User Manual

L8124A,C,E,L and M  
Aquastat® Relays  
INSTALLATION INSTRUCTIONS  
APPLICATION  
SPECIFICATIONS  
These immersion type controllers are used with forced  
hydronic heating systems that include domestic hot water  
service. All models provide high limit, low limit and  
circulator control. Table 1 lists the various models and  
their applications.  
Low Limit:  
Setting: 110°F to 220°F (43°C to 104°C), adjustable.  
Differential: 10°F to 25°F (6°C to 14°C), adjustable.  
High Limit:  
Setting: 130°F to 240°F (54°C to 116°C), adjustable.  
Differential: 10°F (6°C), fixed.  
These Aquastat® relays have a diaphragm powerhead  
and MicroSwitch™ assembly that respond to  
temperature changes in the boiler water. L8124 can  
provide multizone control by using a separate circulator  
and R845 Relay for each zone. L8124E and L have large  
transformers and extra terminals for supplying power to  
low voltage valves. L8124L includes a large transformer  
and extra terminals for low voltage zone valves. L8124M  
is for use in a wood-coal/gas-oil multifuel heating system.  
Circulator is independently controlled by the thermostat.  
WARNING  
Can cause serious injury, death or property  
damage.  
Use this product only in systems with a pressure  
relief valve.  
Explosion Hazard.  
Do not use these Aquastat® Relays where the pressure  
can exceed 100 psi (690 kPa) on the bulb if inserted  
directly or 200 psi (1380 kPa) when using an immersion  
well, or where the ambient temperature can exceed  
150°F (66°C) at the case or 265°F (129°C) at the sensing  
element.  
Table 1. Model Descriptions.  
No. of V8043 Zone  
Electrical Ratings  
Can Be Used For  
Multizone With  
Burner  
Control  
Number Circuit  
L8124A 120V  
L8124C  
Valves Powered  
Without Additional  
Transformer  
Model  
a
Circulators  
Burner Circuit  
Circulator Circuit  
Yes  
Same as L8124A,C,L  
circulator rating.  
120 Vac: 7.4A (full load),  
44.4A (locked rotor).  
240 Vac: 3.7A (full load),  
22.2A (locked rotor).  
L8124L  
3
2
L8124E 24V  
1.25A at 24 Vac; 30 VA  
(total load) B -B , T -Z.  
1
2
v
L8124M 120V  
Same as L8124A.  
None.  
a
Multizone control can be provided by using a separate circulator and R845 Relay for each zone.  
® U.S. Registered Trademark  
Copyright © 2001 Honeywell • All Rights Reserved  
95- 6571- 11  
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
BACK OF  
CONTROLLER  
CASE  
IMMERSION  
WELL CLAMP  
CONTROLLER  
CASE  
BOILER  
IMMERSION  
WELL CLAMP  
1
IMMERSION  
WELL SPUD  
ADAPTER  
IMMERSION  
WELL CLAMP  
SCREW  
ADAPTER  
OLD IMMERSION  
WELL ASSEMBLY  
SENSING  
BULB  
(A)  
(D)  
)
(B)  
2
HEAT-CONDUCTIVE COMPOUND  
1
2
BEND THE CAPILLARY TUBE TO HOLD THE SENSING BULB IN GOOD  
THERMAL CONTACT WITH THE IMMERSION WELL AT POINTS (A) AND (B).  
CAPILLARY  
TUBE  
ASSURE THAT CAPILLARY TUBE FITS FREELY IN THE ADAPTER SO THE  
TENSION OF THE CAPILLARY TUBE AT POINT (C) HOLDS THE SENSING  
BULB IN GOOD THERMAL CONTACT WITH THE IMMERSION WELL AT POINT (D  
SETSCREW  
SHORT TUBE  
FITS IN CENTRAL  
RECESS OF ADAPTER  
IMMERSION  
WELL CLAMP SCREW  
Fig. 2. Position of bulb in immersion well and use of well adapter when required.  
LOW VOLTAGE  
THERMOSTAT  
LOW VOLTAGE  
THERMOSTAT  
L8124A,C  
G
L8124E  
2
2
G
T
Z
TV  
L1  
(HOT)  
L1  
(HOT)  
T
T
1
2
1
2
1K  
L2  
1
L2  
1
1K  
1K2  
W
R
W
R
B
B
1K1  
1K1  
LOW LIMIT/  
CIRCULATOR  
LOW LIMIT/  
CIRCULATOR  
ZR  
ZC  
LINE VOLTAGE  
CIRCULATOR  
R
B
HIGH  
LIMIT  
C1  
C2  
LINE VOLTAGE  
OIL BURNER  
RELAY OR  
B
HIGH  
LIMIT  
1K2  
GAS VALVE  
3
3
R
B1  
TR  
TH  
B1  
B2  
B2  
C1  
LOW VOLTAGE  
GAS VALVE  
(eg, VR8300)  
C2  
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
2
3
LINE VOLTAGE  
CIRCULATOR  
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND.  
USE GROUNDING SCREW PROVIDED.  
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
M8803  
B1 IS 1/4 IN. TAB TERMINAL.  
2
3
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND.  
USE GROUNDING SCREW PROVIDED.  
Fig. 4. L8124E single zone connections  
and internal schematic.  
M8802  
B1 IS 1/4 IN. TAB TERMINAL.  
Fig. 3. L8124A,C single zone connections  
and internal schematic.  
3
95-6571—11  
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
T87F  
T87F  
T87F  
L8124A  
R845 RELAY  
R845 RELAY  
ZC  
ZR  
B1  
T
T
T
1
T
2
T
1
T
2
3
2
G
C1  
3
6
3
6
C2 B2  
4
5
4
5
L1  
L2  
L2  
L1  
(HOT)  
1
PUMP  
PUMP  
PUMP  
R8184  
T
F
C554  
T
F
ORANGE  
BURNER  
AND  
IGNITION  
BLACK  
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND. USE GROUNDING SCREW PROVIDED.  
B1 IS 1/4 IN. TAB TERMINAL.  
2
M8822  
3
Fig. 5. L8124A in an oil-fired, forced hot water, tankless, zoned, pump system.  
TO ADDITIONAL  
R845A RELAYS  
FOR OTHER ZONES  
L2  
L1  
(HOT)  
LOW VOLTAGE  
THERMOSTAT  
1
2
L8124A,C  
G
R845A RELAY ZONE 2  
ZONE 2  
CIRCULATOR  
T
T
1
2
6
5
3
1K  
W
R
B
1K1  
LOW LIMIT/  
CIRCULATOR  
4
1
ZR  
ZC  
LINE VOLTAGE  
OIL BURNER  
RELAY OR  
B
2
HIGH  
LIMIT  
1K2  
GAS VALVE  
3
ZONE 2  
LOW VOLTAGE  
THERMOSTAT  
R
B1  
B2  
C1  
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
2
3
CONTROL CASE MUST BE CONNECTED TO EARTH  
GROUND. USE GROUNDING SCREW PROVIDED.  
C2  
LINE VOLTAGE  
CIRCULATOR  
B1 IS 1/4 IN. TAB TERMINAL.  
M8827  
Fig. 6. L8124A,C multizone system with circulator connections and internal schematic.  
95-6571—11  
4
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
1
ZONE 1  
THERMOSTAT  
ZONE 2  
THERMOSTAT  
L1  
(HOT)  
T87F  
V8043F  
V8043F  
L2  
2
TH  
TR  
TH  
TR  
G
L8124E  
L2 L1  
C1 C2  
T
T
3
TH  
TR  
TH  
TR  
2
B2 B1  
L8124G,L  
3
G
1
T
Z
TV  
TH  
TR  
L1  
(HOT)  
1K  
CIRCULATOR  
LOW VOLTAGE  
GAS VALVE  
(eg, VR8300)  
2
1
L2  
1K1  
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
W
R
B
ZR  
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND.  
USE GROUNDING SCREW PROVIDED.  
LOW LIMIT/  
CIRCULATOR  
ZC  
B1 IS 1/4 IN. TAB TERMINAL.  
M1796A  
LINE VOLTAGE  
OIL BURNER  
RELAY OR  
B
R
1K2  
HIGH  
LIMIT  
Fig. 8. L8124E in a 24Vac, gas-fired,  
forced hot water, tankless system.  
GAS VALVE  
4
B1  
B2  
C2  
C1  
LINE VOLTAGE  
CIRCULATOR  
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
2
UP TO TWO V8043F ZONE VALVES CAN BE POWERED WITH  
L8124G,L. ADD ADDITIONAL TRANSFORMER FOR EVERY  
TWO OR LESS VALVES.  
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND.  
USE GROUNDING SCREW PROVIDED.  
3
4
M1795B  
B1 IS 1/4 IN. TAB TERMINAL.  
Fig. 7. L8124 multizone system with zone valve  
connections and internal schematic.  
5
95-6571—11  
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
T87F  
T87F  
T87F  
R845 RELAY  
R845 RELAY  
R845 RELAY  
T
1
T
2
T
1
T
2
T
1
T
2
3
6
3
6
3
6
4
5
4
5
4
5
1
L1  
(HOT)  
PUMP  
PUMP  
PUMP  
L2  
2
G
L2 L1  
C1 C2  
T
T
LOW VOLTAGE  
GAS VALVE  
(eg, VR8300)  
TH  
TR  
B2 B1  
3
L8124E  
AQUASTAT RELAY  
®
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
CONTROL CASE MUST BE CONNECTED TO EARTH GROUND. USE GROUNDING SCREW PROVIDED.  
B1 IS 1/4 IN. TAB TERMINAL.  
M1794A  
Fig. 9. L8124E in a 24 Vac, gas-fired, forced hot water, tankless, zoned pump system.  
1
TO ADDITIONAL  
R845A RELAYS  
FOR OTHER ZONES  
L1  
(HOT)  
L2  
R845A RELAY ZONE 1  
6
5
3
L8124E  
2
G
T
Z
TV  
4
1
1
2
1K  
2
1K2  
ZONE 1  
LOW VOLTAGE  
THERMOSTAT  
W
R
B
1K1  
LOW LIMIT/  
CIRCULATOR  
R
B
ZONE 1  
CIRCULATOR  
HIGH  
LIMIT  
C1  
C2  
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
2
3
TR  
B1  
B2  
THTR  
TH  
CONTROL CASE MUST BE CONNECTED TO EARTH  
GROUND. USE GROUNDING SCREW PROVIDED.  
LOW VOLTAGE  
GAS VALVE (eg, VR8300)  
B1 IS 1/4 IN. TAB TERMINAL.  
M8828  
Fig. 10. L8124E multizone system with circulator connections and internal schematic.  
95-6571—11  
6
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
LOW VOLTAGE  
THERMOSTAT  
ZONE 1  
1
TO ADDITIONAL  
R845A RELAYS  
FOR OTHER ZONES  
L2  
L1  
(HOT)  
L8124L  
2
G
T
Z
TV  
R845A RELAY ZONE 2  
ZONE 2  
CIRCULATOR  
1
2
1K  
6
5
3
1K1  
W
R
B
ZR  
ZC  
LOW LIMIT/  
CIRCULATOR  
4
1
B
R
1K2  
HIGH  
LIMIT  
3
2
B1  
LINE VOLTAGE  
OIL BURNER  
RELAY OR  
ZONE 2  
LOW VOLTAGE  
THERMOSTAT  
B2  
C2  
GAS VALVE  
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND  
OVERLOAD PROTECTION AS REQUIRED.  
1
2
3
C1  
LINE VOLTAGE  
CIRCULATOR  
ZONE 1  
CONTROL CASE MUST BE CONNECTED TO EARTH  
GROUND. USE GROUNDING SCREW PROVIDED.  
B1 IS 1/4 IN. TAB TERMINAL.  
M8829  
Fig. 11. L8124L multizone system with circulator connections and internal schematic.  
EXAMPLE: Setpoint of 140°F (60°C), differential set  
at 25°F (14°C). On a temperature rise, R-B breaks  
and R-W makes at 155°F (68°C). On a temperature  
fall, R-B makes and R-W breaks at 130°F (54°C).  
OPERATION  
High Limit Controller  
The high limit opens and turns off the burner when the  
water temperature reaches the setpoint. The high limit  
automatically resets after the water temperature drops  
past the setpoint and through the 10°F (6°C) differential.  
SWITCH BREAKS ON  
TEMPERATURE RISE.  
BURNER TURNS OFF.  
CIRCULATOR OPERATES  
ON A CALL FOR HEAT.  
HIGH LIMIT  
SETTING  
WARNING  
Can cause serious injury, death or equipment  
damage.  
SWITCH MAKES ON  
TEMPERATURE FALL.  
BURNER OPERATES ON A  
CALL FOR HEAT.  
Explosion Hazard.  
Use this product only in systems with a pressure  
relief valve.  
SWITCH MAKES R-W  
AND BREAKS R-B ON  
TEMPERATURE RISE.  
1
LOW LIMIT  
AND  
CIRCULATOR  
SETTING  
Low Limit and Circulator Controllers  
SWITCH MAKES R-W  
AND BREAKS R-B ON  
TEMPERATURE RISE.  
On a temperature rise, with the adjustable differential at  
the minimum setting of 10°F (6°C), the burner circuit  
(R-B) breaks and the circulator circuit (R-W) makes at  
the control setpoint. On a temperature drop of 10°F (6°C)  
below the setpoint, the R-B circuit makes and the R-W  
circuit breaks. See Fig. 12.  
SWITCH MAKES R-B AND  
BREAKS R-W ON  
TEMPERATURE FALL.  
BURNER IS ON TO  
MAINTAIN MINIMUM  
WATER TEMPERATURE.  
CIRCULATOR IS OFF.  
At any differential setting greater than 10°F (6°C), the  
R-B make temperature and the R-W break temperature  
remain the same (control setting minus 10°F [6°C]). The  
R-B break and R-W make temperature are the setpoint  
temperature plus the difference between the differential  
setting and 10°F (6°C).  
1
WHEN WATER REACHES PROPER TEMPERATURE, THE BURNER  
SHUTS OFF OR THE CIRCULATOR PUMP STARTS (WHEN CALLING  
FOR HEAT).  
M1523  
Fig. 12. Relationship of setpoints and differential.  
7
95-6571—11  
 
L8124A,C,E,L AND M AQUASTAT® RELAYS  
On the L8124M, the burner and circulator circuits are  
separately controlled; the low limit controls the burner  
circuit (R-B) as described above, while the low voltage  
thermostat directly controls the circulator circuit.  
See Fig. 13.  
SETTING  
Follow the boiler manufacturer recommendations when  
making the L8124 settings. The high limit setting must be  
at least 20°F (11°C) higher than the low limit setting. Set  
the indicators over the selected temperature marks. The  
low limit differential is set by turning the differential  
adjustment knob to the desired amount of differential.  
The thermostat heat anticipator should be set at 2.0A.  
LOW VOLTAGE  
THERMOSTAT  
2
L8124M  
G
CHECKOUT  
L1  
(HOT)  
T
T
L1  
L2  
Put the system into operation and observe each function  
through at least one complete cycle. Be sure the control  
operates as intended.  
L2  
1
1K  
ZC  
1K1  
LINE VOLTAGE  
CIRCULATOR  
W
R
B
C1  
C2  
LOW LIMIT  
LINE VOLTAGE  
OIL BURNER  
RELAY OR  
B
R
HIGH  
LIMIT  
3
GAS VALVE  
B1  
B2  
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
1
2
CONTROL CASE MUST BE CONNECTED TO EARTH  
GROUND. USE GROUNDING SCREW PROVIDED.  
M8804  
3
B1 IS 1/4 IN. TAB TERMINAL.  
Fig. 13. L8124M single zone connections  
and internal schematic.  
Automation and Control SolutionsAutomation and Control Solutions  
Honeywell  
Honeywell Limited-Honeywell Limitée  
1985 Douglas Drive North  
Golden Valley, MN 55422  
35 Dynamic Drive  
Scarborough, Ontario  
M1V 4Z9  
95-6571—11 G.R. Rev. 12-01  
 

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