March 20

Troubleshooting Your Instant Gas Hot Water System

Like any appliance or system in your home – your gas hot water heater can experience issues from time to time. Knowing how to troubleshoot your water heater can help you determine if something is a minor fix or needs attention from a professional plumber.

Our troubleshooting guide will go over step-by-step solutions to the most common issues with instant gas hot water systems so you can get back to hot water on demand.

How Does an Instant Gas Hot Water System Work?

Instant gas water heaters warm up water as you need it instead of holding heated water in a storage tank. Cold water travels into the system so a gas burner can heat it as it flows through a coiled copper pipe called a heat exchanger. The heat is applied directly and results in instant hot water.

No heated water needs to be stored at any point, and the gas burner only activates when the hot tap is turned on. This means both energy and cost savings.

The Most Common Problems With Instant Gas Hot Water Heaters

Begin troubleshooting your system here. These are the most common issues our customers have with their instant gas hot water systems.

Cold water flowing through the tap

If you’re noticing that only cold water is coming through your tap, this may suggest an issue with the heat exchanger. Here are some things to investigate:

No electricity to the unit – Make sure power is turned on and is working.

No gas to the unit – Check that your gas is on and supplying gas to other gas appliances if applicable.

Low flow rate that won’t trigger the sensor – Have you recently installed “low flow” fixtures? Try running several taps to see if increased flow fixes the problem.

Pilot light turned off – See if the pilot light triggers when a hot water tap is turned on. Ensure there is enough flow to trigger the flow sensor. If you’ve checked the above, an issue with the pilot light or ECU should be addressed by a plumber/gas fitter.

Blocked gas vent – A blocked gas vent in the heat exchanger stops the exchanger from fully firing. This requires a call to a professional.

ECU not working properly – See if turning the hot water system on and off resets the ECU. If it doesn’t work, call a plumber/gas fitter.

Low hot water pressure

If the hot water pressure is low, check if the cold water has low pressure also. If both are low, the problem likely isn’t your gas hot water system.

Otherwise, you need to check:

Blocked strainer valve – The strainer valve that removes solids near the inlet valve might be blocked and need cleaning or replacement.

Mineral buildup – Try flushing your system per the manufacturer manual instructions.

Faulty thermostat – Call a plumber/gas fitter.

Intermittent hot water

If your hot water intermittently turns cold during use, check the following:

Insufficient flow of gas – Low gas flow can affect your heat exchanger. Call a professional if this seems to be the problem.

Low water flow – If the water flow is too low, this can affect the flow sensor and cause the ECU to turn the heat exchanger on and off intermittently.

An instant gas hot water system in Brisbane

Still Confused?

If your instant gas hot water system is giving you trouble, call S&J Plumbing and Gasfitting. Our experienced experts will get your system diagnosed and repaired fast, so you don’t have to go without hot water for longer than you need to! We work with top water heater brands like Rinnai, Dux, Awuamax, Vulcan, and more. Schedule now.

Contact us today!


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