Sta-Rite Pool Heater won't start

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Mauibob

Member
Jun 1, 2021
5
Maui Hawaii USA
I have a Sta-Rite pool heater that won't start and the Service System light is on. The heater is about 8 feet below the hot tub and the water is flowing when the pump is running. There are no other indications as to what might be wrong. When the pump is running it shows my set temperature reading of 104. The water is only 83 degrees in the hot tub. I believe it's getting gas and the ignition does not come on either. Any ideas?

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Mauibob said:
. When the pump is running it shows my set temperature reading of 104. The water is only 83 degrees in the hot tub.

View attachment 340063
Click to expand...

Welcome to TFP.

When the pump is running the display should show the water temperature and only show the set temperature for a few seconds after you press the up or down arrow.

You could have a bad thermistor temperature sensor. The heater is not going to turn on if it thinks the water temp is equal to your set point temp.

You could also have a bad keypad.

Or the main board could be bad.

The easiest and least expensive check is to put a 10K resistor in place of the thermistor. It should read 76 degrees +/- 1 degree. If it reads correctly with the 10K resistor in place then your main board is good and you need to replace the thermistor.

Only install the 10K resistor as a test.

Below are pic of doing the 10K resistor test on my Pentair MasterTemp which is internally identical to your Sta-Rite heater. I used some nails and alligator clips to connect the 10K resistor to the connectors.

10K Resistor Test Rig1.jpg

10K Resistor Test Rig1.jpg


Pentair MasterTemp with 10K Resistor Test.jpg

Pentair MasterTemp with 10K Resistor Test.jpg


Pentair MasterTemp with 10K Resistor Temp.jpg

Pentair MasterTemp with 10K Resistor Temp.jpg


You can also use a multimeter to check the resistance of the thermistor to determine what water temperature it is reading. See Temperature Sensors - Further Reading
 
Mauibob said:
the Service System light is on.
Click to expand...
Service System means that the pressure switch is not closing.
Mauibob said:
The heater is about 8 feet below the hot tub
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A pressure switch is not appropriate for a heater 8 feet below the water because the static pressure can close the pressure switch and cause the heater to fire with no flow.

8 feet is 3.5 psi, which is enough to close the 3 psi pressure switch.

A flow switch is what you should install instead of a pressure switch.

You should shut off the heater until you can install a flow switch.
 
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The water pressure switch, (see Figure 28). If the water flow is restricted, the water pressure switch may prevent the burner from firing and cause the “Service System” light to go on.

NOTICE: When the heater is mounted more than five feet (1.5M) above or four feet (1.2M) below the deck level, a Pressure Switch is no longer adequate. A Flow Switch must be installed instead.

If water pressure is outside of adjustment range that will open switch with pump off and close switch with pump on, replace with flow switch set above minimum flow requirement.

Model.... Minimum Flow

200...... 20 gal/min.

175..... 20 gal/min.

250..... 25 gal/min.

300..... 30 gal/min.

400..... 40 gal/min.

If the heater is installed more than 5’ above the pool or more than 4’ below the pool level, you will be beyond the limits of the pressure switch and a flow switch must be installed. Locate and install the flow switch externally on the outlet piping from the heater, as close as possible to the heater. Connect the flow switch wires in place of the water pressure switch wires.

The water pressure switch is set in the factory at 3.00 PSI (± 0.75 PSI). This setting is for a heater installed at pool level. If the heater is to be installed more than 1’ above or below, the water pressure switch must be adjusted by a qualified service technician.


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