Chapter SIX: SENSORS
TEMP/OH SENSORS:
HOW IT WORKS: Sensors work by reacting to temperature at the bulb. As the
temperature raises or lowers, the resistance inside the sensor bulb changes. The
board reads the resistance of the temperature and knows what the temperature
of the spa is. That is how is determines spa temp. Some spas have their
temperature sensor inserted into the actual spa. Others in a housing inserted into
the spa.
The second sensor is the Overheat or high limit sensor. If that sensor raises
above a certain threshold, usually 112-115 degrees, it shuts the spa down. It is
clipped against the heater.
Typical Resistance Values for Sensors and the water temperature.
Temperature
Resistance
59
55.0
65
40.0
77
30.0
84
25.5
94
20.2
99
18.1
101
17.2
104
16.2
106
15.4
108
14.7
110
14.1
115
12.7
23