Burner Temperature Limit Switch - This is a single-use switch which detects abnormal burner temperature.
It is a disc-type switch which is held against the burner plenum by a sheet metal bracket.
It has the appearance of an automatic reset switch in that it has no reset button.
However, it will reset only if cooled to -31o F, and therefore will not recycle.
The burner limit switch prevents or interrupts burner operation if the burner plenum becomes too hot.
You might have an airflow issue.
Check the Combustion Air Filter.
4B. Induced-Draft Combustion System.
The Hi-E2 pool heater has an advanced combustion system which makes it highly efficient and reliable.
This system is illustrated in Figure 30.
A special corrosion resistant high-speed blower pulls flow through the system and exhausts it to the outdoors.
Air is pulled into the system through a combustion air supply duct, when provided, and through an air filter into a venturi.
The venturi functions much like an automobile carburetor venturi -i.e. when air is forced through it, a “negative” pressure is created at the venturi throat.
This negative pressure pulls gas through a metering orifice, resulting in an optimal mixture of air and fuel gas.
The air and gas are thoroughly mixed in the venturi tailpipe, pulled through a special burner and ignited in the combustion chamber.
Hot combustion products are then pulled through a highly efficient downward-flow heat exchanger.
Combustion products are cooled below their dew point and condensate water is formed and drained away.
Flow then enters the blower, where it is forced out of the heater at the vent terminal or through a vent pipe to the outdoors.
