If the light on the control panel on top of your Sta-Rite pool and spa heater labeled “service system” is on, the following should be done to diagnose why your Sta-Rite heater is not working. A systematic approach will help narrow down the problem and possibly resolve it without having to call a repair person. There are many things that can go wrong, but many of the problems are simply fixed with the use of a few basic tools. For this first segment you will only need a 5/16 screwdriver or nut driver and a basic multimeter. Additional segments will go into other aspects of systematic problem solving.

Before beginning any diagnosis, there are a few things that need to be checked. These items are the first two things to check on any gas heater. This is a gas heater so you first turn on the gas to the heater and have plenty of fuel in the tank. Next up is the electrical for the heater. Make sure all circuit breakers and/or switches in the heater circuit are turned on. (By the way, this last item should be the first thing you check on any non-functioning pool or spa equipment.)

Now start with the basics. Without proper water flow, the heater will not work.

1. Does the pool pump work? It doesn’t work, there is NO water flow.

2. Does the system filter need to be cleaned? Again, if the water flow is compromised, the heater will not work. In a sand filter, this is usually accomplished with a simple backwash to remove dirt and debris. A DE filter can help with a backwash or it may need a more thorough cleaning. The cartridge may need to be removed from a cartridge filter and thoroughly cleaned or replaced if it is old and cleaning does not increase water flow.

3. Are all system valves in the correct positions? The flow to the heater may have been cut off. And again the result is NO heat. Or some of the flow may be diverted from the heater or restricted and the heater does not have enough flow to operate.

4. The last item under the water flow would be a faulty water pressure switch. To get to the water pressure switch so you can test it, you must first remove the 2 piece outer cover from the heater. You will need to remove the four screws that hold the sides together. The screws can be removed with a regular screwdriver or a 5/16 socket or nut driver. The pressure switch is located on the upper right hand side of the water trap, facing it. With your electrical ohm meter, the pressure switch should indicate a full short. The meter will read 0 or beep. This is the same result you’ll get if you set your meter to ohms and touch the 2 leads of the meter. If it reads open, you have a problem. Open is a meter reading of nothing or a meter reading like you have a meter that is on and switched to ohms and the leads are not touching anything. If you have verified that you have a good flow of water; I’m sure your pressure switch is bad. You will need to get a new pressure switch and install it. If you get anything on your meter other than a dead (closed) short or a solid open, you have a problem. Anything in between means you could have a bad switch or dirty contacts. Make sure you have good contacts. Clean the contacts and retry your readings.

To replace the pressure switch if it is necessary to do so. First turn off the pool pump. Then disconnect power to the heater. Remove the wires from the switch and unscrew the switch by turning it counterclockwise. Screw in the new pressure switch clockwise, being careful to set it up straight. It is plastic and has fine threads and can be easily damaged. Then connect the cables. I would recommend that if you have the ability to put new connectors on the cables, but if they are clean and intact it is not an absolute necessity. Turn on the pool pump and then turn on the power. Now you can close the heater with its four screws and in a short time enjoy your heated pool.

This segment has only dealt with one of the most common reasons for a pool and spa heater not working and heating your pool or spa. Come back to follow the steps to go further.