Cleaning sludge from expansion tank
(A, Fig. 9)

Confirm that tank has sludge and needs cleaning. To do this, run a wooden stick through the filler all way to bottom of tank and try to move its tip back and forth in the fluid. If you detect resistance to its movement the tank has sludge. Withdraw stick and inspect its tip for further evidence of sludge. If sludge is present, clean the tank as follows:

1. Set switch HEATER CONTROL (Fig. 5) to OFF. Allow the circulation pump (and auxiliary pumps on HC heaters) to continue operating for approximately 10 minutes.

2. Set switch CIRC. PUMP to OFF. For HC heaters, set all switches labeled AUX. PUMP to OFF. Let the system cool.

3. Close Valves No. 1, 2 and 4 (K, E, and N, Fig. 9).

4. Place a container under the drain valve (Fig. 6). You will probably have to empty the container several times as you drain thermal fluid from the expansion tank.

   NOTE: Wear chemical and heat resistant gloves as shown in Fig. 6.

5. Open drain valve to drain thermal fluid from expansion tank. Some sludge will drain out with the thermal fluid. Do not re-use this fluid. Dispose of it properly.

6. Remove the drain valve, the square flange, and the strainer basket from the strainer (M, Fig. 9).

   NOTE: Sludge will exit the strainer. Make provisions to capture the sludge so you can dispose of it properly.

7. Insert a long spray nozzle from a pressure washer into the tank through the fill opening (A, Fig. 9). Wash until clean. Allow as much washing solution as possible to drain from the expansion tank.

8. Clean the strainer basket with fuel oil, then dry completely with compressed air.

9. Re-install strainer basket, square flange, and drain valve.

10. Refill tank with clean thermal fluid.

11. Purge system as instructed in OPERATION section.

12. After purge, set valves for RUN as indicated in Fig. 3.

Figure 15. Removing fuel pump coupling.

Removing fuel pump coupling

1. Shut down heater per previous instructions.

2. Turn off main circuit breaker (Fig. 12) and lock it off.

3. Remove the nuts from around the burner fan motor (O, Fig. 9).

4. Pull the burner fan motor out of the burner housing.

5. The fuel pump coupling will either come out with the burner motor or remain on the fuel pump. Pull off the coupling. (See Fig. 15.)

6. Re-install burner fan motor.

7. Unlock main circuit breaker (Fig. 12) and turn it on.

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