If the light on the control panel on top of your Sta-Rite pool and spa heater that is labeled “service system” is on, the following should be done to diagnose why your Sta-Rite heater is not working. running. 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 some 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 starting 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 the gas is turned on to the heater first and it has enough fuel in the tank. Next 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 malfunctioning pool or spa equipment.)

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

1. Does the pool pump work? Doesn’t work, NO water flow.

2. Is it necessary to clean the system filter? 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 may help with a backwash or 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 valves in the system in the correct positions? Perhaps the flow to the heater has been cut off. And again the result is NO heat. Or some of the flow may be bypassing the heater or restricted and the heater does not have enough flow to operate.

4. The last item under the flow of water would be a faulty water pressure switch. To get to the water pressure switch so you can test it, you must first remove the outer 2-piece cover from the heater. You will need to remove the four screws holding the sides. 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 towards it. With your electric meter in ohms, the pressure switch should indicate a full short. The meter will read 0 or beep. This is the same result you will get if you set your meter to ohms and touch both leads on the meter. If it reads open, you have a problem. Open is a meter reading of nothing or a meter that reads 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; Surely 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 malfunctioning switch or dirty contacts. Make sure you have good contacts. Clean the contacts and try your readings again.

To replace the pressure switch if it is necessary to do so. First turn off the pool pump. Next, turn off the power to the heater. Remove the wires from the switch and unscrew the switch by turning it counterclockwise. Screw in the new pressure switch in a clockwise direction, being careful to position it 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. You can now close the heater with its four screws and in a short time enjoy your heated pool.

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