Scope
This document applies to HC heaters (Fig. 1) and HCS heaters. It provides instructions for checking devices that can open the 3-to-P limit circuit and initiate a shutdown of the heater.

Figure 1. Heatec HC heater with side pumps.

Intended users
Instructions in this document are intended for use by qualified asphalt plant operators and maintenance personnel. Qualified persons are those who understand electrical shock hazards and how to avoid them. Such persons are also familiar with the burn hazards of working with liquid asphalt and thermal fluids heated to temperatures in excess of 300 degrees F.

Some procedures require setting and testing parts inside the heater electrical control panel while it is open and electrical power is turned on. This should be done only by qualified persons using electrical testers to make sure wires and terminals they may accidentally touch are deenergized so that no electrical power is present.