The secondary components include removable panels, a control panel, a control box, a fuel hose
assembly, an electrical power cable assembly, a water hose assembly, a boiler assembly, a combustor
assembly, two electrical motors, a magneto, a filter, and tools.
The controls located on the M2 water heater are the HEATER-ON/PURGE-ON switch, the temperature
selector control, the water and fuel pressure gages, and the water temperature gage. These controls are
shown in Figure 11 and are described in the following paragraphs.
HEATER-ON/PURGE-ON Switch. The HEATER-ON/PURGE-ON switch in the PURGE-ON position
applies operating voltage to relays that energize the fuel and ignition drive motor. Placing the switch in
the HEATER-ON position closes the fuel pump solenoid valve, admits fuel into the combustion
chamber, and fires the boiler.
Temperature Selector Control. The temperature selector control (Figure 11) is used to manually set the
desired operating water temperature. Turning the knob clockwise will raise the water temperature;
turning the knob counterclockwise will lower the water temperature. Increasing water temperature will
increase fuel pressure.
Water Pressure Gage. The water pressure gage indicates the pressure of water being circulated through
the boiler. Normal water pressure indications are from 60 to 155 psi. When the water pressure
indication exceeds 200 psi, the pressure relief valve on the boiler opens and relieves excess pressure.
Fuel Pressure Gage. The fuel pressure gage (Figure 11) indicates the pressure of the fuel being supplied
to the fuel nozzle for atomizing and burning. Since the M2 water heater has a multifuel capacity,
different fuel atomizing pressures are required. The pressures required for various fuels are indicated in
Figure 12. Pressure for various fuels used in the M2 water heater.