Setting Barksdale pressure switches
The Barksdale switches (Fig. 4) should be set after the system has been filled with thermal fluid and air has been purged from the system. However, they should be set before the burner is operated to purge water from the system.

Purging water from the system
This procedure requires firing the burner and heating the thermal fluid.

The burner has been factory tested. Factory settings should be adequate for all operations covered in this procedure. However, burner tuning can be affected by local altitude or other atmospheric conditions and should be re-tuned after initial operation. See Tec-Note entitled “How to recognize an out-of-tune burner.” Only a thoroughly qualified burner technician should re-tune the burner.

At some point after step 12 of this purge procedure you should check limit circuit devices for proper operation. Instructions for checking limit devices are provided in a separate Tec-Note.

Note: Purging the system can take from two hours to two days or longer, depending on the amount of thermal fluid in the system and the amount of moisture in the thermal fluid.

1. Set the power disconnect switch (the handle) on the control panel (Fig. 2) to ON.

2. Make sure the MODULATING CONTROLLER and the HIGH MEDIA TEMP. CONTROLLER are set per previous instructions.

3. Make sure thermal fluid circuits are filled per previous instructions. Thermal fluid level should be 3 inches in the sight gauge (Fig. 5.)

4. Make sure drain valve (Fig. 6) is closed.

5. Make sure valves are set as indicated in Fig. 8 for purge.

6. For HC heater, make sure the auxiliary valves on the manifold are open.

7. Set the switch labeled FUEL SELECTOR (Fig. 2), to either OIL or GAS, depending on the fuel you are using.

   For GAS:

   Open the main gas manual shutoff valve (Fig. 7).
   Open the secondary gas manual shutoff valve (Fig. 7).
   Open the pilot gas manual shutoff valve (Fig. 7).
   Make sure fuel oil supply valve (not furnished with heater) is shut off.

   For OIL:

   Open fuel oil supply valve (not furnished with heater).
   Open the pilot gas manual shutoff valve (Fig. 7).
   Make sure the main gas manual shutoff valve (Fig. 7) is closed.
   Make sure the secondary gas manual shutoff valve (Fig. 7) is closed.

8. Set the switch labeled CIRC. PUMP to ON (Fig. 2).

9. For HC heaters, set all switches labeled AUX. PUMP to ON.

10. Set the MODULATING CONTROLLER (Fig. 2) to manual. The message MAN should appear in the upper portion of the display.

    The message OUT (burner output) should appear in the lower portion of the display. Adjust the burner output to 0.0%.

    Note: The output’s lowest setting is -5.0%, not 0.0%. Make sure you set it at 0.0%.

    You may have to increase output (using the LOWER DISPLAY key) to achieve enough heat to reach the desired set point of 200 degrees F. Likewise, as you increase the set point in the following steps, you may need to increase the output. Increase the output in increments of about 10 percent.

11. Momentarily set the switch labeled HEATER CONTROL to ON (Fig. 2). and make sure rotation of blower motor is in the direction marked on the motor.

12. Set the switch labeled HEATER CONTROL to ON (Fig. 2). After about 2 minutes the Fireye flame monitor should display the message AUTO FLAME SIGNAL. This indicates that the burner has ignited properly.

13. Observe the MODULATING CONTROLLER (Fig. 2.) The temperature of the thermal fluid should rise to the set point of 200 degrees F. Water and steam will exit the overflow pipe. Operate the heater at this temperature until no water or steam exits the overflow pipe.

    Note: This can take from 45 minutes to several hours, depending on the amount of moisture in the system.

14. On the HIGH MEDIA TEMP. CONTROLLER, reset the set point to 260 degrees F.

15. On the MODULATING CONTROLLER, reset the set point to 210 degrees F.

    Observe the MODULATING CONTROLLER. The temperature of the thermal fluid should rise to its new set point of 210 degrees F. Operate the heater at this temperature until no water or steam exits the overflow pipe. This can take from 45 minutes to several hours.

16. On the HIGH MEDIA TEMP. CONTROLLER, reset the set point to 270 degrees F.

17. Reset the MODULATING CONTROLLER to 220 degrees F. Operate the heater until no steam or water exits the overflow pipe.

18. Set valve No. 1 (K, Fig. 3) to half open.

19. Continue this cycle of raising the set point on the HIGH MEDIA TEMP. CONTROLLER and the MODULATING CONTROLLER in increments of 10 degrees. Each time you raise the set point, operate the heater until no steam or water exits the overflow pipe. Continue this cycle until you reach the set point of 320 degrees F on the MODULATING CONTROLLER.

    Note: 320 degrees F is a typical set point for heater operation at an asphalt plant. The desired set point at your facility may be higher.

    Note: if you attempt to save time by increasing the temperatures in increments larger than 10 degrees there is a risk of boiling over the expansion tank. Likewise, if you do not wait until all steam has exited the overflow pipe, there is risk of boiling over the expansion tank.

20. Adjust the set point on the HIGH MEDIA TEMP. CONTROLLER (Fig. 2.) See Fig. 9 for suggested settings. Note that the desired settings at your facility may differ from those shown.

21. Set the MODULATING CONTROLLER (Fig. 2) to auto. The letter A should appear in the upper portion of the display.

22. Set valves as indicated in Fig. 8 for Run.

23. Reset the pressure differential switches according to separate Tec-Note on setting Barksdale pressure switch.