Pressure differentials on HC heaters
Pressure differentials for HC heaters (Figure 3), which are heaters with side pumps, vary according to the size of the heater. Appropriate settings for the pressure differential switches must be determined during initial startup of the heater.

Our experience indicates that most HC-120 heaters in normal operation typically produce the values shown in Figure 5. However, other sizes of HC heaters will have different pressure differentials.

Pressure differentials on HCS heaters
Pressure differentials for HCS heaters (Figure 2), which are heaters without side pumps) vary according to the installation and according to size of the heater. Appropriate settings for the pressure differential switches must be determined during initial startup of the heater.

Procedure for setting switches
This procedure applies to all current Heatec thermal fluid heaters, including those used in industrial facilities as well as those used in the HMA industry.

The system should be filled with thermal fluid and purged of air according to instructions in applicable Heatec documents. Bleed the two gauges (Figure 4) to remove air. Make sure the strainer is clean and there are no signs of leaks.

It’s not necessary to run the burner to purge the system of water or moisture at this point. Accordingly, you can disregard current settings of the differential pressure switches.

Note: This procedure is for an initial startup of the heater, before the thermal fluid has been heated higher than ambient air temperature. After you make the initial settings of the differential switches, you will need to repeat this procedure while the burner is operating and while the thermal fluid is heating up. You may also need to repeat the procedure again after the thermal fluid has reached its normal operating temperature.