TM 5-3895-374-24-2HEATEROPERATIONALSAFEGUARDSCEI heaters are equipped with numerous safety controls to ensure a safe and reliable operating environment. Abrief discussion of each of these safeguards follows.LOWLEVELCONTROL-ensures that the circulating pump and the burner will not operate if the heat transfer fluidlevel in the. expansion tank is too low. The LOW OIL light on the panel will also be lit.PUMPPRESSURESWITCH-ensures positive circulation of the heat transfer fluid before the burner will operate.For example, if there is water in the heat transfer fluid, then as the temperature of the fluid approaches 2120F, thewater will be converted to steam and will expand. This is potentially an extremely dangerous situation. When thesteam reaches the pump, the pump will lose pressure and the safety switch will prevent the burner from operating.FLAMESAFEGUARDSYSTEM-consists of the mini peeper, the flame amplifier module, program module and theheater operation programmer. The main fuel supply is shut off and the FLAME FAILURE light on the panel box islit if burner ignition fails. Also, the normal operating cycle of the programmer includes a pre-purge and post-purgephase to ensure that no combustible gases remain in the firebox when burner ignition is attempted.PROOF-OF-CLOSURESWITCH-on gas operation, ensures that the electric gas valve closed properly following thelast burner cycle. If the electric gas valve failed to close properly, the burner will not attempt to ignite.AIRFLOWSWITCH-on gas operation, ensures that the burner blower is mixing air in the firebox with the gas beingsupplied to the burner. If not, the burner will not ignite and the programmer will continue to cycle.LOWFIRESTARTINTERLOCK-ensures that the burner is low-fire mode during ignition. If not, ignition will not beattempted.HIGHTEMPERATURELIMITSWITCH-shuts off the heater if the heat transfer fluid temperature reaches 450°F(575°F for heaters set for high temperature operation). This switch works in conjunction with the temperaturecontroller which has a set point limit of 450°F programmed in it at the factory. The two devices provide atemperature limit at two locations on the heater.TEMPERATURECONTROLLER-uses a thermocouple to indicate the heat transfer fluid temperature in thecirculating pump's pressure line. If a thermocouple failure was to occur, the temperature controller would read thefalse signal as an infinite temperature and prevent operation of the heater.BY-PASSVALVE-ensures that heat transfer fluid will continue to circulate through the heater even if all externalvalves are closed. This valve must remain open when the heater is operating.page 3-915
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
