A Siebe thermostat for water tanks is a simple device that can be adjusted for your specific situation with very little effort. You can easily adjust the thermostat to a specific temperature to maintain the water at or simply set the heater to be always on or off. Before you can adjust the thermostat effectively you will have make sure that the unit is positioned properly on the tank.
Release the spring clip that is holding the thermostat in place. Pull the hook and the eye toward each other until the hook can be lifted up and out of the eye.
Measure the height of the tank and divide it by three to find the positioning for the unit. So if your tank if your tank is 12 feet tall and you divide it by three you would get 4 feet and you should place your unit at 4 feet.
Place the unit at the height you calculated and reattach the spring clip. Make sure the line on the spring clip rests firmly in the horizontal groove on the front of the Siebe unit.
Insert the tip of the flat head screwdriver into the groove in the arrow shaped dial. Make sure you use a screwdriver that fits properly into the groove or the dial will not move.
Turn the dial clockwise as far as it will go to set the thermostat to be constantly on. If you turn the dial all the way to the left, you will turn off the thermostat.
Move the dial until the point of the arrow is pointing at the number you want to adjust the temperature to. This will allow the thermostat feature to function properly.
Siebe recommends 15.6 degrees Celsius as a popular thermostat temperature setting.
Do not leave the thermostat fully on or off if you will not be around to monitor the temperature of the water carefully.