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Automatic Fill/Low Water Heat Protection
Dual Float Switches
Each tank contains a dual oat switch.
The part consists of an angled stem containing two reed
switches. Two stainless steel ball oats, containing magnets,
slide over the stem and are free to move up and down. When
the oat moves on the stem, it opens and closes the
associated reed switch inside the stem. The reed switches
control relays. The relays control the automatic ll and heat for
different parts of the machine. The oat switch(es) and their
relay(s) operate on a 120VAC circuit.
Operation Sequence
Bottom Float and Reed Switch
• The bottom float controls the heat.
• When the bottom float is down, the bottom reed switch contacts are open.
• When the bottom float is up, the bottom reed switch contacts are closed.
Top Float and Reed Switch
• The top float controls a fill valve, which controls the water level.
• When the top float is down, the top reed switch contacts are open.
• When the top float is up, the top reed switch contacts are closed.
Initial Fill
• When the tank is empty, both floats are down and their reed switch
contacts are open.
• The control relay for the float switch is de-energized.
• The fill valve for the tank is energized and the tank begins to fill with water.
• As the water level in the tank rises, the bottom float begins to move up.
• When the bottom float is completely up, its reed switch contacts close.
• This prepares the heat circuit, but the heat DOES NOT energize at this time.
• The tank continues to fill until the top float is completely up.
• The top float’s reed switch contacts close. Its control relay energizes.
• The fill valve de-energizes.
• The heat circuit energizes through the contacts of the control relay.
Electrical • Basic Service
Electrical Service (continued)
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