Page 7 American Metal Ware Hot Water Boiler
II)
III) Quick Service Check of Dual Level Control System:
Description and Operation of Dual Level Control System (continued)
B. Operation
W
ater Level Action
1) Below both electrodes 1)
2) Rises to low electrode 2)
above heater coils
3) Rises to high electrode 3)
4) Falls below high electrode only 4)
5) Falls below low electrode 5)
(Same as condition no. 1)
1)
2)
3)
Both “HI” and “XL” electrode circuits open.
Dual Level Control turns power on to fill
valve and keeps power off to thermostat.
“XL” electrode circuit closes. Power to
thermostat turned on. Power to fill valve
remains on.
“HI” electrode circuit closes. Dual Level
Control turns power off to fill valve and
continues power to thermostat.
“HI” electrode circuit opens. “XL” circuit
stays closed. After a few seconds delay,
power to fill valve is turned on.
“XL” electrode circuit now opens. Power to
thermostat is turned off. Power to fill valve
remains on.
All
wire secure and properly connected.
Clean the electrodes. Lime (mineral scale) build-up can interfere with the operation of any
liquid level control system.
Check the common (ground) connection. A little looseness or dirt can cause erratic
operation.
Thermostat
Fill Solenoid
Valve
OFF
ON
O
Thermostat
Fill Solenoid
Valve
ON
ON
O
O
O
Thermostat
Fill Solenoid
Valve
ON
OFF
Thermostat
Fill Solenoid
Valve
ON
ON