Grindmaster 850, 815, 830 service manual Onoff

II) Description and Operation of Dual Level Control System (continued)

B. Operation
Water Level	Action
1) Below both electrodes	1) Both “HI” and “XL” electrode circuits open.
	Dual Level Control turns power on to fill
	valve and keeps power off to thermostat.
	Fill Solenoid	Thermostat
	Valve
		O

ONOFF

2)Rises to low electrode above heater coils

2)“XL” electrode circuit closes. Power to thermostat turned on. Power to fill valve remains on.

	Fill Solenoid				Thermostat
	Valve	O
		ON		ON
3) Rises to high electrode	3) “HI”	electrode	circuit	closes.	Dual Level
	Control turns power off to fill valve and
	continues power to thermostat.
	Fill Solenoid				Thermostat
	Valve	O
		OFF		ON
4) Falls below high electrode only	4) “HI” electrode		circuit	opens.	“XL” circuit
	stays closed. After a few seconds delay,
	power to fill valve is turned on.
	Fill Solenoid			Thermostat
	Valve	O
		ON		ON
5) Falls below low electrode	5) “XL” electrode circuit now opens. Power to
(Same as condition no. 1)	thermostat is turned off. Power to fill valve
	remains on.

III)Quick Service Check of Dual Level Control System:

1)All wire secure and properly connected.

2)Clean the electrodes. Lime (mineral scale) build-up can interfere with the operation of any liquid level control system.

3)Check the common (ground) connection. A little looseness or dirt can cause erratic operation.

Page 7 American Metal Ware Hot Water Boiler