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 running. A systematic approach will help narrow down the problem and possibly resolve it without calling a technician. There are many things that can go wrong, but many of the problems are solved simply with the use of a few basic tools. For this first segment you will only need a screwdriver or a 5/16 spanner and a basic multimeter. Additional segments will address 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 the heater gas is turned on first and you have enough gas in the tank. Next is the electricity to start the heater. Make sure all breakers and / or heater circuit breakers are turned on. (By the way, this last item should be the first thing you check on any non-working pool or spa equipment.)
Now start with the basics. Without adequate water flow, the heater will not work.
1. Is the pool pump running? It does not work, there is 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 can help with a backwash or it may need a more thorough cleaning. It may be necessary to remove the cartridge from a cartridge filter and clean it thoroughly or replace it if it is old and cleaning does not increase water flow.
3. Are all valves in the system in the correct positions? Flow to heater may have been cut off. And again, the result is NO heat. Or maybe some of the flow is bypassing the heater or is 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 and be able to test it, you must first remove the 2-piece outer shell of 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 5/16 nut driver or socket wrench. The pressure switch is located in the upper right-hand side of the water trap, when looking at it from the front. With your electric meter in ohms, the pressure switch should read as a 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 the 2 meter leads together. If it says open, you have a problem. Open is a meter reading of nothing or a meter that reads like you have a meter turned on and switched to ohms and the wires are not touching anything. If you have verified that you have a good flow of water; your pressure switch is probably bad. You will need to obtain a new pressure switch and install it. If you find anything on your meter other than a short (closed) or 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 try your readings again.
Replace the pressure switch if necessary. First turn off the pool pump. Then 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 clockwise, taking care to position it straight. It is made of plastic and has fine threads and can be easily damaged. Then connect the cables. I would recommend that if you have the capacity you 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 while enjoy your heated pool.
This segment has only addressed one of the most common reasons why a pool and spa heater does not work and heats up your pool or spa. Go back to follow the steps to get further.