How to Troubleshoot a Gas Hot Water System That Won’t Ignite

*Collaborative Post

There’s nothing worse than jumping in the shower on a cold Adelaide morning and getting hit with icy water. If your gas hot water system won’t ignite, you’re probably standing there wondering whether it’s something simple or something that’s about to cost you.

The good news is that ignition failure is one of the most common gas hot water problems around, and quite a few causes are things you can check yourself before picking up the phone.

It doesn’t matter whether your system’s brand new or been running for fifteen years, ignition faults crop up on both.

In this guide, we’ll go through why gas hot water systems fail to ignite, what you can safely check at home, and when it’s time to stop troubleshooting and call in a licensed professional.

Why Won’t My Gas Hot Water System Ignite?

Gas hot water systems ignite in slightly different ways depending on the type you’ve got. Knowing which one you own helps narrow down what’s actually gone wrong.

Continuous Flow (Instantaneous) Systems

Most Adelaide homes now run continuous flow units. These heat water on demand instead of storing it in a tank, using an electronic ignition system that sparks up when you turn on a hot tap.

They’ve become the go-to option for most new installations because they’re compact, never run out of hot water mid shower, and don’t need a bulky tank taking up space outside. If you’re weighing up your options, this comparison of heat pump vs instant hot water systems breaks down the differences.

Common reasons these fail to ignite include:

• Flat batteries in the ignition control, since many units run on AA batteries even though they’re gas powered
• Low water flow that isn’t enough to trigger the flow sensor
• A tripped safety switch or power interruption at the wall
• Wind interference, since these units usually sit outside and strong gusts can blow out the flame sensor
• A blocked or dirty igniter

Storage Systems with a Pilot Light

Older storage tank systems rely on a standing pilot light that has to stay burning all the time. If that pilot’s gone out, the whole system won’t fire up.

Wind and drafts are common culprits. So is a worn out thermocouple, which is the small safety sensor that cuts gas flow if it can’t detect a flame.

Troubleshooting Steps You Can Try Yourself

Before you assume the worst, run through a few checks most homeowners can safely do.

• Check your gas supply first. Try lighting the stove or another gas appliance. If nothing else is working either, the problem is your gas supply, not the hot water unit.
• Look at the isolation valve. Make sure it hasn’t been knocked or turned off, especially if you’ve had any work done near the unit lately.
• Check for an error code. Most continuous flow systems have a small digital display that flashes a fault code when something’s wrong. Jot it down and check your manufacturer’s manual, since it’ll usually point straight to the cause.
• Swap the batteries. If your unit runs on batteries for ignition, this is one of the cheapest and most common fixes going.
• Check the power point and switchboard. A tripped safety switch will stop the unit igniting even if gas is flowing just fine.
• Turn the tap on fully. A partially open tap sometimes doesn’t create enough flow to trigger ignition, especially on units with a minimum flow requirement.
• Check your LPG bottle if you’re not on mains gas. It’s an easy one to overlook. If the bottle’s empty or running low, that’s your answer right there.
• Look at the unit itself. If it’s mounted outside, check nothing’s blocking the air intake or flue, and take note if it’s a particularly windy day.

If you’ve worked through this list and it’s still not igniting, chances are it’s something inside the unit that needs a proper look.

How to Prevent Ignition Problems in the Future

A bit of regular upkeep goes a long way with gas hot water systems.

Get your system serviced every year or two, especially once it’s ten years old or more. A standard service usually checks the burner, ignition components and flue, which happen to be exactly the parts that cause ignition trouble when they’re left unchecked.

Keep the area around your unit clear of leaves, spiderwebs and general debris, particularly heading into windier months. Spiderwebs building up inside the burner assembly are a surprisingly common cause of ignition faults in Adelaide homes.

If your system’s getting on in years and you’re facing repeat call outs, it might be worth thinking longer term. According to Sharpe Services, it pays to weigh up the gas hot water pros & cons before deciding between a repair and a full replacement.

When to Call a Professional

Some things are fine to check yourself. Others aren’t, and gas is one area where it genuinely pays to be careful.

If you smell gas at any point, stop what you’re doing, don’t try to light anything, and call 1800 GAS LEAK straight away.

Beyond the basic checks above, anything involving the pilot assembly, thermocouple, gas valve or internal wiring needs a licensed gasfitter.

This isn’t just a recommendation either. Based on South Australian gas safety regulations, a licensed gasfitter must handle any work between the gas meter and a faulty appliance, including situations where it won’t stay alight or is burning incorrectly.

Before you call, jot down the model number of your unit and any error code showing on the display.

It sounds like a small thing, but it often means a technician can bring the right part with them on the first visit instead of having to come back a second time.

A licensed tradie can also tell you fairly quickly whether it’s a small part that needs replacing or whether the system’s reaching the end of its working life.

Conclusion

A gas hot water system that won’t ignite is frustrating, but it’s rarely a mystery. Most of the time it comes down to something fairly straightforward, like a flat battery, a tripped switch, low water flow or a bit of wind interference on an outdoor unit.

Run through the basic checks first. If everything looks fine on your end and it’s still not firing up, that’s your cue to bring in someone licensed to look at what’s happening inside the unit.

Either way, a cold shower on a Tuesday morning doesn’t have to turn into a week without hot water once you know what to check.

*This is a collaborative post. For further information please refer to my disclosure page.