20VAC
24 VAC
E.C.O.
R1 (N.C.)
2M
FUSE
On Appliance Call for Heat - Stage 1
The thermostat contacts close and they relay coil is energized.
Relay contacts R1 (N.C.) now open, and the motor is
Relay contacts R2 (N.O.) now close.
R2 (N.O.)
SS2 (N.O.)
3 | 1 |
TH.E.S.(N.O.) 4
VENT DAMPER
VALVE
GND.
20VAC
24 VAC
E.C.O.
R1 (N.C.)
2M
FUSE
On Appliance Call for Heat - Stage 2
The flue damper spring begins to operate to return the damper blade to the open position to permit operation of the appliance.
During this damper blade movement, the mechanically operated switches (SS1, SS2, and E.S.) change their operating positions, which results in the following:
R2 (N.O.)
SS2 (N.O.)
3 | 1 |
TH.E.S.(N.O.) 4
VENT DAMPER
VALVE
GND.
Page 8
When the switch SS2 opens, it causes the SS1 switch to close. When the damper blade reaches the full open position, the switch contacts ES close and the electrical circuit energizes the igni- tion system.
