A.O. Smith Water Heater Troubleshooting Guide

A.O. Smith water heaters have been around since 1939. These water heaters are considered some of the best that homeowners can get their hands on for their outstanding quality and durability. 

But that does not mean that these magnificent water heaters are perfect. Various things can suddenly go wrong with an A.O Smith water heater.

Whether your A.O. Smither water heater smells strange, has a leak, or has stopped working altogether, this guide will provide steps for fixing it—including how to check the pilot light and clear the vents.

AO smith water heater

If you are looking for troubleshooting tips for your A.O. water heater, you came to the right place.

A.O Smith Water Heater Has Stopped Working

The primary purpose of an A.O. Smith water heater is to raise water temperature, but it is not as simple as that. Life without a water heater can make the whole family uncomfortable, especially during winter.

These heaters are very popular because they are economical yet top-notch performers known to last. However, issues can arise with these water heaters and other A.O. Smith models. Common problems include odor, sooting, leaks, and pilot light issues.

As an essential component in your home, it can be frustrating when your A.O Smith water heater malfunctions or stops working altogether. Being aware of common issues and tips to troubleshoot it can help.

Gas Odor from Soot Build-Up

One of the issues that A.O. Smith water heater owners sometimes report is the smell of gas where the water heater is or in another part of the house. This situation can be alarming since smelling gas in your home can lead you to believe that there’s a combustible gas leak.

The most likely issue here is obstructed vents. This can result in soot buildup, which in turn can heighten fuel costs. Soot can prevent a lot of generated heat from transferring into your system’s water.

Other operating problems and possibly even fire safety issues can ensue if this is not taken care of as quickly as possible:

  • Check your A.O. Smith water heater’s venting path to ensure that dirt, grime, or anything else is not obstructing it. 
  • If the vent is blocked in a way you cannot fix, you might need to turn to professionals for help.
AO Smith Water Heater

Leaking Water from Loose Connections

Misfitted plumbing connections cause most water leaks, not the tank. A loosely threaded connection on your A.O. Smith water heater can leak water, driving up water bills and causing water damage.

To find and fix these leaks on your water heater:

  • Find the water lines on top and the drain valve at the bottom right side of the unit. Check these to see if any escaping water is evident. 
  • After that, check the thermostat connections in the front. 
  • Although these are the points where water might usually leak, you should also check the rest of the unit. 
  • If you come across leaking connections, carefully tighten them until they are secure and no longer leaking.

Bad Smell from Mineral Buildup

A foul odor might lead you to believe that the tank in your A.O. Smith water heater is corroded or impaired in another way, but that is probably not the case. 

Foul smells from a water heater can be attributed to your water supply having a high concentration of sulfate or minerals. To prevent this, you have to flush the water tank regularly.

Of course, there is not much that you can do about your town or city’s water supply, but you can get rid of a sour smell from your own A.O. Smith heater. 

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Pilot Light Problems

Lack of any hot water at all might indicate that the pilot light on your A.O. Smith gas water heater is not on.

The pilot light is the flame in your unit that fires up the gas burner to heat the water in your home. It might be small, but it is vital, so you are sure to notice when it goes out. 

  • Ensure that your gas has not turned off. 
  • Check for hot water. If the main burner on your A.O. Smith water heater fails to ignite, you will not have any hot water. 
  • Check for a clogged igniter, blocked gas line, or damaged thermostat.

A common issue with gas lines for water heaters is dirt and other debris, which blocks it. In this case, you have to:

  • Turn the gas off.
  • Clean out the gas line.
  • Once you have cleaned out your gas line, you should do the same with the pilot light line. You can find the pilot light on your A.O. Smith Proline water heater close to the main burner.
  • You can clean these lines using tweezers or compressed air.

While doing this, it is also necessary to check everywhere for signs of corrosion since this can hinder the system and keep it from lighting. Have a good look at the gas control valves, as that is where corrosion typically occurs.

If you still experience issues with the pilot light, you can try changing the thermostat.

Safety When Troubleshooting an A.O. Smith Water Heater

All A.O. Smith water heaters require regular maintenance, but the company itself does not recommend anyone who is not qualified to do so themselves. Remember that you can always turn to professionals for help.

Having said that, keep safety in mind if you choose to do maintenance on your A.O. Smith Proline water heater yourself. 

Various dangerous situations can arise when working on a water heater, including third-degree burns from scalding water and explosions from steam buildup. Extinguish the pilot light and employ other safety steps before continuing.


You now have important information about common troubleshooting steps for A.O Smith water heaters. If an issue persists after trying these steps, we suggest hiring a technician for help.