Spark Ignition Pool Heater Troubleshooting Guide

Sparker

Welcome to our guide on troubleshooting spark ignition pool heaters. In this article, we will focus on electronic pool heaters from the mid-1980s to the late 1990s.

A spark ignition is similar to an electronic gas stovetop. Instead of a pilot light, it uses a spark to ignite the burner, quickly igniting the burner orifices. The same principle applies to gas pool heaters.

These new generation gas pool heaters are a whole new game. They no longer have a pilot generator or mechanical thermostat. Electronic heaters are wired with 110V or 220V power directly to a transformer, which steps the power down to 24V. The transformer powers the entire ignition and safety system, controlled electronically by the ignition controller (PCB).

However, aside from the IID controller, transformer, redesigned electronic thermostat, gas valve, and pilot, electronic heaters still function the same way as millivolt heaters. Once the safety system is approved, the gas valve opens, releasing gas into the burners. The pilot light ignites the first burner, and the others follow suit - whoosh!

To troubleshoot a pool heater, you will need a multimeter that can measure low voltage levels like 24 volts. You can find them at Walmart, Home Depot, or Radio Shack for less than $20. You don't need an expensive meter to inspect a pool heater.

Troubleshooting Lane for Electronic Pool Heaters

For our example heater, we'll use the Teledyne Laars Series I Series II Spark Ignition Heaters, manufactured from 1986-1997. However, the concepts apply to electronic heaters made by Raypak, Hayward, or Purex - RP2100, H-Series, or Minimax Plus heaters.

The diagram below is from the Teledyne Laars Series One heater, model EPS/EPC, and Laars Series 2 ESC. The dual thermostats shown here allow you to maintain two pre-set temperatures, and you can select between Spa or Pool mode using a 3-position switch. That's all there is to it. In fact, if your Pool Thermostat (potentiometer) fails, you can use the Spa thermostat to heat the pool.

What we have here is a schematic diagram of the safety system in an electronic gas pool heater. The transformer (1) steps down the incoming power to 24 volts and creates a circuit loop from one side of the gas valve to the other.

When the power successfully passes through all the components (fuse, fusible link, high limits, pressure switch, thermistor), and returns to the ignition controller (6), the gas valve (8) should open, allowing gas to flow into the pilot, which is ignited by a small spark (7A) created by the spark ignition wire. The pilot (7B) is temporarily ignited, which ignites the burners. Whoosh!

Let's take it step by step...

Step 1: Transformer Inspection

If your heater has no power at all, check for a tripped circuit breaker or a popped GFCI outlet. Then verify that you have incoming and outgoing 24 volts from the transformer. Set your multimeter to VAC (AC Volts), on a low range of 100 or 200 volts. Place each probe on the metal spot contacts of the transformer to verify 22-26 volts, not more - not less.

Also, inspect the wires for any signs of damage due to heat or rodents. If you're not getting 24 volts at the transformer, replace the transformer (pn R0061100), as they can sometimes go bad.

Steps 2 3: Fusible Link Inspection

With the black or common lead of your multimeter remaining on the yellow wire side of the transformer, slide the red lead to different heater components, starting with the fusible link, a small white part located near the burners to detect flame roll-out. Slide your red meter lead to both sides of the fusible link. If you find power coming in (2) but not going out (3), you have either a bad inline fuse (pn 10480000) or a bad fusible link (pn R0012200).

The cause of a failed fusible link must be investigated. It could be material on the burners, leaves or nests on top of the heat exchanger, high winds blowing in, or soot or scale deposits between the copper heat exchanger fins.

Steps 4 5: Pressure Switch / High Limit Inspection

With the black wire attached to the transformer (an alligator clip adapter for a test probe is useful), slide the test probe to the pressure switch (R0011300) and check for 24 volts at each pressure switch spade terminal. Make sure you're touching the brass metal of the terminal. If there is no power going into the pressure switch, make a jumper and test each high limit (4B, 4C) and the Fireman's Switch terminal (which bypasses the heater for 15 minutes before the pump's timer turns it off, for a cool-down period). Remember - the problem lies where the power is dead!

If the high limits (R0023200 and R0022700) trip or are the cause of the problem, inspect the internal bypass assembly (pn R0054900) in the front header for broken, missing, or improperly placed parts. A temperature rise can be done with a special thermometer inserted into the drain plug hole (pn R0336000) to see how high the temperature rises inside the header.

If you find no voltage or less than 24 volts on the black wire (outgoing) of the pressure switch, check for a dirty filter, dirty pump or skimmer baskets, or closed or partially closed valves or broken check valves. Also, check for an external bypass, a valve outside the heater that allows too much water to bypass the heater.

Step 6: Thermostat Inspection

For this step, slide your red lead over to the black/yellow striped wire on the Ignition Control Box, to the terminal labeled 24V. Again, make sure you're touching the metal connector on the controller without removing the wire, although you can disconnect it if needed. Turn the thermostat up, and the On/Off switch in the correct position.

If there is no 24V at this terminal, replace the Temperature Board (pn R0011700), and if there is 24V but no heat, it is likely the Thermistor (pn R0011800).

Step 7: Spark Inspection

For Step 7A, check if there is a spark at the gap by removing the Spark Ignition wire, pulling back the rubber boot, and holding it close to the connector. With the thermostat turned up, the call for heat should send a small visible electrical spark across the gap from the end of the rubber-insulated wire to the connector. If there is no spark, check the stainless steel wire running from the Ceramic Insulator to the Pilot (R0099000) to make sure the power is not grounding to the burner tray or any other metal piece. Also, check and clean where the SS wire attaches at the bottom of the pilot. Perform a visual inspection of the position of the pilot and spark ignition to ensure there are no nests, insects, or debris and that everything is intact. If you have followed the steps so far and have 24V up to the Spark Ignition wire but no spark is jumping, the problem might be the Ignition Controller or IID (Intermittent Ignition Device) (R0011900).

Step 7B, the pilot (7B) lights, but you have no ignition or burner light-up; using your multimeter in the same settings and position as mentioned above, check for 24V on the Orange Wire on the Gas Valve. If yes, look for blockages in the pilot or burner orifices, or in the gas supply. You may also suspect the volume and pressure of the gas supply at this point, as propane tanks may be low, or other high-demand natural gas appliances may be in use. First, consider and inspect the wires, looking for sharp bends or kinks in the wire insulation, and make sure wire nuts, screws or connectors are clean (not rusty) and secure. If damage is found, replace the wire harness (pn R0058100), and it is possible that the Ignition Controller is still the problem. Plate boards in the good old outdoors tend to fall off in 8-10 years.

Step 8: Gas Valve Inspection

If you've made it this far, with a burning pilot and 24V on the Orange wire of the Gas Valve, now look for 24V on the Brown wire on the gas valve. If not, your brown wire is highly suspect, or the Power Board (Ignition Control) is scrambled. If you have power, at 24V (or at least 22V) on the Brown wire, and the heater still won't ignite - give the gas valve a little tap with a hammer (seriously!). If it still doesn't ignite, the electronic components inside the valve have failed, replace the gas valve (R0095900 and Nat pn R0099400). Be cautious of a clogged inlet screen as you remove it.

Before you go and spend several hundred dollars on a new gas valve or ignition controller, go through the steps again to make sure - I hate for you to buy pool heater parts that don't fix the problem!

And... I almost forgot - here's the link for over 150 pool heater parts schematics! Support your local pool blog!

Thank you for reading!
Mark Garcia

Frequently Asked Questions

What is a spark ignition pool heater?
A spark ignition pool heater is an electronic heater that uses spark ignition technology instead of a pilot burner. It uses a spark to ignite the heaters' burners.
How does the spark ignition system work?
The spark ignition system consists of a transformer, ignition controller, spark ignition wire, and gas valve. When the ignition controller sends power to the spark ignition wire, it creates a spark that ignites the pilot and lights the burners.
What is the process for troubleshooting a spark ignition pool heater?
The following steps can be taken to troubleshoot a spark ignition pool heater:

Step 1: Transformer inspection
Steps 2 3: Fusible link inspection
Steps 4 5: Pressure switch / high limit inspection
Step 6: Thermostat inspection
Step 7: Spark inspection
Step 8: Gas valve inspection

For full details on each step, refer to the complete troubleshooting guide.

What are the most common causes of problems with a spark ignition pool heater?
The most common causes of problems with a spark ignition pool heater include:

Defective transformer
Fusible link or inline fuse issues
Problems with the pressure switch or high limit switch
Faults in the thermostat or thermistor
Issues with the spark ignition or pilot
Problems with the gas valve or power board

However, it is important to go through all the steps in the troubleshooting guide to identify the specific cause of your problem.

Is it difficult to troubleshoot a spark ignition pool heater?
Troubleshooting a spark ignition pool heater can be somewhat technical but can be done with the right knowledge and tools. However, if you are unsure or not an experienced pool technician, it may be advisable to seek professional help to resolve the issue.
Where can I get replacement parts for my spark ignition pool heater?
Replacement parts for spark ignition pool heaters are available from pool suppliers, online retailers, or through the manufacturer's technical support team. It is important to obtain the correct part numbers for your specific heater model and to purchase from a reliable source.