Bradford White DB-80R3DS - Manual (Page 6)

SEQUENCE OF OPERATION
Residential and light duty commercial electric water heaters are designed to operate using 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 voltage is 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-by mode, waiting
for the next call for heat.
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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