Water Heater Repair Tutorial: Initial Troubleshooting Tips

In the first article in this four-part series, the author goes through how to approach the troubleshooting process upon arrival at the customer’s home

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One of the most basic skills a plumber should have is repairing a tank-type water heater.

Older models of tank-type water heaters have a simple control package with a standing pilot. However, newer models have electronic spark ignition packages with additional sensors that can seem confusing to the untrained plumber. When faced with a gas control issue with a water heater, many plumbers go directly to the stage of selling the homeowner a new unit. In many cases this is the correct step considering the cost of replacement gas control packages, the time to disassemble and reassemble them, and the time it takes to diagnose the problem. In most cases a technician will find a small problem with the ignition system, order a part, wait for it to arrive, and re-dispatch to install it only to find another problem that was the cause or the result of the first problem. At around $100 per hour it is cheaper to replace the tank. 

Where the replacement route has its issues is when the tank is under warranty and the customer expects it to be repaired. It is also a necessary skill to have in your arsenal to be able to perform routine diagnostics on a newer tank-type water heater. It will make you a better troubleshooter, give you an excellent understanding of how gas controls work, and help you work on larger and more confusing equipment in the future.

This four-part series is for the plumber who needs a quick and simple test method for the different controls that are used for this type of water heater, as well as some practical advice on common noncontrol troubleshooting.

On Arrival

As with every troubleshooting session, simple solutions should be explored first. Listen to what the customer is saying and start going over the basics.

By basics I don’t mean get your manometer and multimeter out. The first thing to do is simply think. Is there gas pressure at all? Is the gas meter locked out or red tagged? Is the flue pipe clogged with soot? Feel the chimney wall upstairs. Is it smoking hot? Is the gas valve showing a blinking code? What does it say that code means? Have any valves been turned off? Does the entire house have no hot water or is it only a certain room or fixture? Is the flue installed properly? Does the unit exhaust into a chimney or through plastic piping outdoors? Is it pitched and installed correctly? Check the bird screen outside. Is it plugged? Is it cold enough outside to freeze up the exhaust condensate coming out of the side of the building?

Never just assume it is a control failure. Think outside the box and think bigger picture when approaching a troubleshooting session. Even if you find a bad control, you may still find the cause or the result of that control failing. You may even sell a re-pipe, new valves, re-piping of the flue, or a bunch of other preventive maintenance items that the customer might appreciate. Do a thorough job. 

Now that you have gone through the basics and they all check out, it’s time to get on the ground and watch the burn process. Watch what happens and think. Where in the startup process does it stop? Can you get a spark? Does it spark but won’t light? Does it light but won’t stay lit? Does it stay lit but won’t bring on the big burner? Does the big burner come on but won’t stay on? Does the big burner come on but get too hot and shut off the unit? Just watch and let it tell you what’s going on.

Begin Advanced Troubleshooting

Now it is time to decide whether it is an issue with the water tank itself, its function, its flow, or the second track which would be the gas controls. Pay attention to what the customer is complaining about, pay attention to your surroundings, and pay close attention to the order of operations of the water heater.

If the unit heats the water and the flame stays on during the entire burn cycle without going off on high limit, then the problem is more than likely with the tank and its nongas control components. If the problem is with the combustion or the gas controls, then cut straight to diagnosing the control package.

In the next article in the series I will cover the specifics of how to test both kinds of issues along with real numbers to follow to successfully diagnose this type of unit.

About the Author

Anthony Pacilla is a registered master plumber for McVehil Plumbing in Washington, Pennsylvania. He has 22 years of experience in the plumbing and HVAC trades, and has a bachelor’s in business and economics from Thiel College. 


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