A.O. Smith 1500, 200 Procedure for Setting Pump Delay, Last Error Mode, Display Stage Cycle Count

Procedure for Setting Pump Delay

The Controller is factory set with a 45 second post circulate function. With the Display Board, the user has the capability to choose between a 45, 90, or 180 second post circulate time period, or turn the pump on continuously. This provides flexibility in selecting the post circulate time to meet specific installation requirements, and improves the efficiency of the circulating pump operation.

To change or view the current programmed post-circulating time:

1.Press the SELECT push-button on the display board until the LED display reads "OP" (Options). See Figure 16.

2.To enter into the options mode, press the ENTER/RESET push-button.

3.The display will illustrate "Crcu". Enter this mode by pressing the ENTER/RESET push-button.

4.The display will now illustrate the current post circulate time. Press the ADJUST push-button to select the desired post circulate time (45, 90, 180, "con").

5.When you have selected the desired post circulate time mode, press the ENTER/RESET push-button once, this enters the selected post circulate time into controller memory.

6.The display will automatically return to illustrating the controlling probe temperature after five (5) seconds.

Last Error Mode

In this mode, the Display Board will illustrate the last error which caused the unit to "lock-out". When this mode is entered the three digit failure code that was in memory last will be displayed. (See table 19 for error codes.) For example, if the appliance "locked-out" due to insufficient air on stage one, the display will show 041. To enter into this mode, perform the following steps:

1.Press the SELECT push-button on the display board until the LED display reads "OP" (Options). See Figure 16.

2.To enter into the options mode, press the ENTER/RESET push-button.

3.The display will illustrate "Crcu". Press the SELECT push-button until the display illustrates "Ler". Enter this mode by pressing the ENTER/RESET push-button.

4.The display will illustrate the last error detected by the control.

5.The display will automatically resort to illustrating the controlling probe temperature after five (5) seconds.

Display Stage Cycle Count

The Central Control Board counts the number of cycles each stage of the appliance has operated by counting how many times the gas valve(s) are energized. To check the cycle count for each stage, perform the following procedure:

1.Press the SELECT push-button on the display board until the LED display reads "OP" (Options). See Figure 16.

2.To enter into the options mode, press the ENTER/RESET push-button.

3.The display will illustrate "Crcu". Press the SELECT push-button until the display illustrates "CC". Enter this mode by pressing the ENTER/RESET push-button.

4.The display will now illustrate the current number of cycles stage one has fired. Notice that the green Stage One LED is illuminated. Pressing the ENTER/RESET button again will cause the green Stage Two LED to illuminate and the cycle

count for stage two will be displayed on the screen. Cycle counts for the other stages can be viewed in a similar fashion.

5.To reset the cycle count to zero, press the ADJUST push- button. Press the ENTER/RESET push-button to successfully reset the cycle count. If the ENTER push- button is not pressed, the reset function will not be saved and the original cycle count will continue to increment on each gas valve operation.

6.The display will automatically return to illustrating the controlling probe temperature after five (5) seconds.

Appliance Operating Sequence

1.When power is applied to the control system, the Display Board will initially run through a self-diagnostic routine, and then go into its operating mode, displaying the temperature sensed at the Inlet probe.

2.If the Central Control Board determines the actual water temperature at the controlling temperature probe is below the programmed temperature set-point minus the switching differential, and the thermostat circuit or tank probe circuit is closed, a call for heat is activated.

3.The control then performs selected system diagnostic checks. This includes confirming the proper state of the ECO/High Limit device, flow switch*, and pressure switches.

*Note: Correct water flow is vital to the operation of the boiler. See table 4 in the Installation manual for requirements on flow, head loss and heat exchanger pressure drop.

4.If all checks are successfully passed, the circulating pump circuit is energized. Once the flow switch has closed, all combustion blowers will energize for a 30 second pre-purge cycle.

5.When the pre-purge cycle is complete, all blowers except stage 1 will drop out. Power is applied to the stage 1 ignitor element for the ignitor warm-up period.

6.The control will verify ignitor current. After the verification, the gas valve will open, allowing gas to enter the burner.

7.After an additional 1 second, the control will monitor the flame sense probe to confirm a flame is present. If a flame is not verified within 4 seconds, the gas valve is immediately closed. The control will initiate an 15 second inter-purge period and return to step 2, unless dip switch "B" is in the "ON" position, see fig. 14, in which case it will proceed to "lock-out".

8.If a flame is confirmed, stage two will be activated. The blower associated with stage two will start. Once the blower has been proven, igniter two will begin its warm-up period. (This is true on all units except the 1000 which has only one igniter.) After the igniter current has been proven, stage two will begin a trial for ignition.

9.Stage three will activate after flame is proven on stage two. If applicable, the blower associated with stage three will begin. Once the blower has been proven, a trial for ignition will begin on stage three. If flame is not proven, there will be a 15 second interpurge on stages with an associated blower. The boiler will then begin additional trials for ignition. On stages without an associated blower, a five second delay will occur before the gas valves are opened for additional trials for ignition.

Note: Stages on which no blower or igniter is present will bypass the blower and igniter proving periods. The gas valves will open five seconds after a call for heat is initiated on the stage.

10.All stages will remain running until the set point for a given stage is satisfied. If all stages are initiated, stage four will

30