34
34
Example 4: Initial Call For High Heat, Subsequent Call To Low Heat
Example 3: Initial Call For Low Heat, Change In Call To High Heat
0 10 30 33 34 64 94 0 15 30 60, 90 90, 120,
120, or 150, or
180 210
Circulator
Blower
Gas Valve
Igniter
Pressure
Switches
Induced Draft
Blower
Thermostat
High
Low
Off
High
Low
Off
On
Off
PS2 Closed
PS1 Closed
Open
High
Low
Off
High
Low
Off
0 10 30 33 34 64 94 0 15 60, 90 90, 120,
120, or 150, or
180 210
Circulator
Blower
Gas Valve
Igniter
Pressure
Switches
Induced Draft
Blower
Thermostat
High
Low
Off
High
Low
Off
On
Off
PS2 Closed
PS1 Closed
Open
High
Low
Off
High
Low
Off
Call Change to High Heat
Call Change to Low Heat
30 Seconds After Call Change to Low Heat
Time (sec)
Time (sec)
(Call For Heat)
(Call For Heat)
4-second
maximum trial
for ignition
period
{
4-second
maximum trial
for ignition
period
{
Timing Charts for Normal Heating Operation