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Drain water from the fuel tank
Before you fill the preheater with fuel, drain all water from the fuel tank. Some fuels may contain up to 2% of water. Therefore a 10,000 gallon tank filled with fuel could include up to 200 gallons of water. Water is heavier than fuel, so it will settle at the bottom of the fuel tank. You must drain water from the fuel tank to avoid filling the preheater with water. If the preheater contains water when hot thermal fluid enters the heating coils, the water can suddenly turn to steam. This results in excess pressure, forcing steam to exit from the pressure relief valve (B, Fig. 3). You should drain water from the fuel tank weekly, or whenever you expect excess water to be in the tank. After all water is drained from the fuel tank, the preheater is ready for startup.

Startup
The very first time you start up the preheater, let it operate for several hours, then shut it down. Let the preheater cool down overnight. Then use a torque wrench to make sure the 7/8-inch nuts at the heating coil assembly flange are tightened to a torque of 520 ft-lbs. Tighten the 1/2-inch nuts at the thermal fluid pipe connections to a torque of 75 ft-lbs.

Note: The torque values cited here for the coil flanges and pipe flanges are for unlubricated or dry threads. These values are different from the values cited in the Maintenance Tec-Note, because you should lubricate the threads when you reassemble the preheater.

1. Before normal daily startups, drain all water that may have condensed overnight from the preheater as follows:

   1. Make sure fuel pump is turned off and preheater has cooled.

   2. Place bucket or suitable container under fuel drain (Q, Fig. 3). The preheater could contain up to 1 gallon of water before startup.

   3. Open the fuel drain shutoff valve (P, Fig. 3) to release water. Water is heavier than fuel, so it will settle at the bottom of the preheater. Therefore, water will drain out before fuel.

   4. When you first see fuel flowing from the drain, close the valve.

   5. Dispose of the collected water and fuel properly according to environmental regulations.

2. Make sure the shutoff valves for the preheater fuel inlet and outlet are open.

3. Activate power to the preheater at the plant breaker panel.

4. Set the main power disconnect switch on the preheater control panel (Fig. 4) to ON.

5. For skid-mounted systems with HFP preheater, set the main power disconnect switch on the power panel for the fuel pump motor starter (Fig. 5) to ON.

6. If you have installed a bypass circuit in the thermal fluid piping to the preheater, make sure the circuit is open to allow thermal fluid to circulate through the preheater.

7. Turn on the fuel pump. If the circulating fuel is cold, the modulating actuator (K, Fig. 3) will immediately open the thermal fluid inlet valve (I, Fig. 3) fully.

Figure 4. Control panel on HFP model preheater.

Figure 5. Power panel for fuel pump motor starter on skid-mounted system with HFP preheater.