HCS heaters—filling circuit
with thermal fluid
This procedure applies to HCS heaters used for heating systems with a single thermal fluid circuit.

The procedure assumes the use of a transfer pump to pump the thermal fluid from its shipping containers into the expansion tank of the heater. Consequently, after the circuit is filled, any excess fluid in the expansion tank can be pumped back into the containers. If you don’t have a transfer pump you must take extra care not to overfill the system. Otherwise, you may have difficulty removing excess fluid from the expansion tank.

This procedure can take 2 hours or longer, depending on the size of the system.

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

2. Set valves as indicated in Fig. 8 for purge.

3. Make sure all valves in the thermal fluid circuit that is connected to the heater are open.

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

5. Remove the cap from the expansion tank filler (B, Fig. 3). Pump thermal fluid from the shipping containers into the expansion tank until the tank is full.

   Leave the cap off of the expansion tank filler. Excess air will exit through this opening as you circulate fluid.

6. Momentarily set switch marked CIRC. PUMP to ON and check the circulating pump motor for proper rotation as marked on pump housing.

7. Set the switch labeled CIRC. PUMP to ON (Fig. 2). The circulating pump (P, Fig. 3) should begin to operate.

   The pump may cavitate intermittently as trapped air escapes from the system. Cavitation can be recognized by a rattling sound. Another indication of cavitation is oscillation of the pressure gauge at the inlet of the coil (Fig. 4). If cavitation does not stop after a few seconds, momentarily close and open valve #4 (N, Fig.3) until cavitation stops and pressure shown on the gauge at the coil inlet (Fig. 4) stabilizes.

   Note: If the circulation pump continues to cavitate, check the pressure gauge at the inlet of the coil. If the gauge indicates a continuing drop in pressure, the strainer may be clogged. In that case, shut off the circulating pump and clean the strainer. You may have to clean the strainer several times during start-up.

8. Observe fluid level in the sight gauge. When its level drops to about 3 inches, set the switch labeled CIRC. PUMP to OFF (Fig. 2). This is a precaution to avoid drawing air into the system.

9. Repeat the previous steps of filling the tank and operating the circulation pump until the system is full. You will know the system is full when the level in the sight gauge does not drop when the circulation pump is operated.

10. When the system is full make sure the fluid level in the expansion tank is 3 to 4 inches as indicated on the sight gauge. This is the normal “cold” fluid level. If the level is higher than 3 to 4 inches, pump excess fluid out of the tank back into the original containers.

11. Replace cap on the expansion tank filler.

    Note: At this point, all air should be out of the system. However, the system must be purged while the burner is operating to remove water and steam. Instructions are given later for purging water.

HC heaters—filling circuits
with thermal fluid
This procedure applies to HC heaters with auxiliary (side) pumps. Side pumps circulate thermal fluid in thermal fluid circuits that can be operated independently. Using this procedure you first fill the heater coil circuit and then each independent circuit, one at a time.

The procedure assumes the use of a transfer pump to pump the thermal fluid from its shipping containers into the expansion tank of the heater. Consequently, after all thermal fluid circuits have been filled, any excess fluid in the expansion tank can be pumped back into the containers. If you don’t have a transfer pump you must take extra care not to overfill the system. Otherwise, you may have difficulty removing excess fluid from the expansion tank.

This procedure can take 2 hours or longer, depending on the size of the circuits.

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

2. Set valves as indicated in Fig. 8 for purge.

3. Make sure all valves at the auxiliary pumps are closed.

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

5. Remove the cap from the expansion tank filler (B, Fig. 3). Pump thermal fluid from the shipping containers into the expansion tank until the tank is full.

   Leave the cap off of the expansion tank filler. Excess air will exit through this opening as you circulate fluid.

6. Momentarily set switch marked CIRC. PUMP to ON and check the circulating pump motor for proper rotation as marked on pump housing.

7. Set the switch labeled CIRC. PUMP to ON (Fig. 2). The circulating pump (P, Fig. 3) should begin to operate.

   The pump may cavitate intermittently as trapped air escapes from the system. Cavitation can be recognized by a rattling sound. Another indication of cavitation is oscillation of the pressure gauge at the inlet of the coil (Fig. 4).

   Note: If the cavitation continues, check the pressure gauge at the inlet of the coil. If the gauge indicates a continuing drop in pressure, the strainer may be clogged. In that case, shut off the circulating pump and clean the strainer. You may have to clean the strainer several times during start-up.

8. Observe fluid level in the sight gauge. When its level drops to about 3 inches, set the switch labeled CIRC. PUMP to OFF (Fig. 2). This is a precaution to avoid drawing air into the system.

9. Repeat the previous steps of filling the tank and operating the circulation pump until the coil circuit is full. You will know the circuit is full when the level in the sight gauge does not drop when the circulation pump is operated.

10. Open the valve at auxiliary pump #1. Make sure that all valves in the circuit connected to this pump are open.

11. Momentarily set switch marked AUX. PUMP #1 to ON and check auxiliary pump motor for proper rotation as marked on pump housing.

12. While the circulation pump is operating, set the switch labeled AUX. PUMP #1 to ON (Fig. 2). Auxiliary pump #1 at the manifold should begin to operate.

    The auxiliary pump may cavitate, producing the same rattling sound mentioned earlier. This may continue intermittently throughout the fill procedure. If cavitation does not stop after a few seconds, momentarily close and open the valve at the outlet of auxiliary pump #1 until cavitation stops and pressure at the outlet of the pump stabilizes.

13. Observe fluid level in the sight gauge. If fluid level drops to about 3 inches, set the switches labeled CIRC. PUMP and AUX. PUMP #1 to OFF (Fig. 2).

14. Repeat the cycle of filling the expansion tank and operating both the circulation pump and the auxiliary pump until the circuit is full. You will know the circuit is full when the level in the sight gauge does not drop when the two pumps are operated.

15. If you have additional auxiliary pumps, repeat steps 10 through 13 above for each additional auxiliary pump.

16. When all ciruits are full make sure the fluid level in the expansion tank is 3 to 4 inches as indicated on the sight gauge. This is the normal “cold” fluid level. If the level is higher than 3 to 4 inches, pump excess fluid out of the tank back into the original containers.

17. Replace cap on the expansion tank filler.

    Note: At this point, all air should be out of the system. However, the system must be purged while the burner is operating to remove water and steam. Instructions are given later for purging water.