We will continue our systematic approach to diagnosing a pool heater by looking at what to do when the light in the control pad on the top of your Sta-Rite pool and spa heater that is labeled “service heater” is lit. (We will proceed with the assumption that you know everything from segment one.) This time you will need to remove the sides from the heater before disconnecting power to the heater so that you can read the codes on the board attached to the topside. After removing the sides, you will see the big topside that is still connected to the heater. Below the topside is a metal panel that keeps the topside in place. Under this panel there are two locking pins (cotter pins). Carefully remove the two pins and store them somewhere safe until reassembly. Gently remove the top and turn it upside down. You will see a light lit on the board you are looking at when you turn the topside over. The light will be next to a code that is written on the board.
The first code that you’ll see on the left side of the board will be PS. This is the code for the pressure switch. We covered the pressure switch in segment one. If this light is lit go back to segment one and review that segment. If necessary follow the instructions to replace the pressure switch.
The next code you’ll see on the board is HLS. If you have a controller on the system you will need to bypass it at this time. You will need to carefully disconnect the power from the heater. After you are sure that the power is disconnected, you will need to find and open the high-voltage cabinet. This cabinet is a metal box in the middle of the heater. If you are looking at the cabinet, there is usually a screw on the top right side. Loosen the screw and the door will swing down toward you. You need to be extremely careful when working in this box and only do so when you are sure that the power to the heater is OFF.
You will need to bypass the firewall safety interface. To do this you will need a short wire with stab-tab connectors. If you have a controller and it was properly installed the wire may have been left in the box by the tech who installed the controller. If not you will need to make this jumper wire. At this point look in your owner’s manual to locate the two proper pins to connect to. If you have a controller or are using a fireman’s switch this is where your control should be connected. If you have a controller and it is not connected here, it could be the source of your problems and either have a certified tech correct the problem or correct it yourself.
You must be careful not to put the jumper wire on the power terminals or you will destroy your heater by burning up the electronic system. Use your manual to locate where the fireman’s switch is supposed to be attached and carefully attach your jumper between these terminals. If you now turn on the power and the heater works without any problems, your problem lies in the controller or the wiring going to the controller. You will need to trouble shoot this system.
If you still have the same problem with your heater. (“service heater” light comes on), leave the jumper in place and verify that the pump is on and that you have good water flow. Make sure again with your meter that the pressure switch is not cycling. It should read as a dead short. (See segment one) With good water flow verified and the “service heater” light on, your problem could be one of the thermo-regulators in the safety system.
Since we started this with the indicator light on the board lit next to HLS, the first thing we are going to check are the wires going to the high limit switch. The high limit switch is located near the bottom on the left side of the water manifold as you face it. To see it you need to remove the side cover on the water manifold. The screw that holds the cover is on the top of it. You need to make sure that the orange wires going to the switch are intact, attached and not corroded. If the wiring is good, use your multi-meter to check that the high limit switch reads as a dead short. If it reads open and the water is not above 104 F, replace the high limit switch. If this does not fix your problem you may have a bad control board and it will need to be replaced. Testing the control board is a very involved process and will be dealt with in a later segment.
This is the end of segment two and has taken you through part of the safety circuit in the heater and 2 of the indicator lights on the board. We will continue on with our systematic diagnose of problems on the Sta-Rite pool and spa heater in the next segment.