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ECH16-20/25kW Y VOLTAGE
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ECH16-20 / 25kW Y VOLTAGE SEQUENCE OF OPERATION
NOTE - Call for heat is first stage heat for CHA16 units and second stage heat for CHP16/20 units.
1- On a call for second stage heat, relay K43 is energized.
K43-1 closes immediately.
2- When K43-1 closes, heat relay K15 and time delay
relay DL2 are energized. K15-1 closes immediately.
DL2 begins 30 second countdown before closing.
When K43-2 closes nothing happens as indoor blower
is already energized from first stage heat call.
3- When K15-1 closes, heating elements HE1, HE2 and
HE3 are energized. HE1, HE2 and HE3 are connected
in a delta" configuration for three-phase operation.
4- After 30 second count, time-delay DL2 closes and enĆ
ergizes heating contactor K16. K16-1 closes immediĆ
ately.
5- When K16-1 closes, heating elements HE4, HE5 and
HE6 are energized. HE4, HE5 and HE6 are connected
in a delta" configuration for three-phase operation.
6- When heating demand is satisfied, heat relay K43 and
all heating elements connected to K15 are de-enerĆ
gized. All heating elements connected to K16 are de-
energized when DL2 contacts open (about one second
later).
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