Bradford White MII50A-SF Service Manual page 11

Sequence of Operation:
Surface Mounted Thermostats.
Line voltage is applied across terminals of fuse block or a
1
terminal block. Line voltage continues down and connects
to surface mounted thermostats at terminals L1 & L3.
ECO (high limit) in
2
thermostat is closed, so
there is line voltage present
at terminal L4 of thermostats
and to one side of each
element.
Water in tank is cold, so
3
all thermostats are
closed at terminal T2
(calling For heat). This
completes the circuit and
allows current to flow
through heating elements.
As each thermostat is
4
satisfied, it opens at
terminal T2 interrupting
current flow through the
respective element. The
system is now in stand-by
mode, waiting for the next
call for heat.
2
ECO Closed
Power to one
side of element
3
Thermostat closed
at terminal T2
4
Thermostat open
at terminal T2
Page 11
SEQUENCE OF OPERATION
Line Voltage
1
OR
Fuse Block
Terminal Block
Surface Mounted
Thermostat
Heating Element
11