SEQUENCE OF OPERATION
Residentialand light duty commercial electric water heaters are designed to operateusing several different operating
modes. The common modes and sequence of operation are as follows:
1.Single Element Operation.
2.Double Element Non-Simultaneous Operation (single phase).
3.Double Element Non-Simultaneous Operation (3 phase).
4. Double Element Simultaneous Operation (single phase).
5. Double Element Simultaneous Operation (3 phase).
Sequence of Operation- Single Element Operation.
Line voltageis applied across terminals
L1 &L3 of the thermostat. ECO is
closed, so there is voltage at terminal L4
and to one side of the element.
1
2
When the thermostat is satisfied,it opens at
terminal T2 interrupting current flow through the
element. System is now in stand-bymode, waiting
for the next call forheat.
3
1
ECO
Closed
2
Thermostat closed
at terminal T2
3
Thermostat opens
at terminal T2
Tank is cold therefore thermostat
is closed at terminal T2 (calling for heat).
This completes the circuit and allows
current to flow through the element.
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