There’s nothing worse than jumping into the shower only to be hit with icy water. If your instant gas hot water system has suddenly stopped working, you’re probably wondering what went wrong – and how you can fix it fast.
These systems (aka continuous flow hot water) are designed to provide hot water on demand, so when they fail, it can be frustrating and disruptive. Fortunately, many issues are common and can be easily identified with a bit of basic troubleshooting. From a lack of gas supply to error codes or low water pressure, there are a few key things to check before calling in a professional.
In this guide, we’ll walk you through the most common reasons your instant gas hot water might not be working – and what steps you can take to get the hot water flowing again.
No Hot Water at All
If your instant gas hot water system isn’t producing any hot water, don’t panic – there are a few common causes worth checking:
- Gas supply issues: Make sure your gas meter or liquefied petroleum gas (LPG) cylinder hasn’t been turned off or run empty. Without gas, the unit can’t heat anything.
- Pilot light or ignition failure: If your system uses a pilot light, it may have gone out. Newer models use electronic ignition, which may fail if there’s a power issue.
- Water flow problems: Instant systems need a minimum water flow to activate. Clogged taps, showerheads, or filters can stop the system from turning on.
- System lockout: Some units shut down when they detect a fault. Reset the unit using the control panel or refer to the manual.
If none of these checks work, it’s best to call a licensed technician to inspect and repair the issue safely.
Water is Only Lukewarm
If your instant gas hot water system is delivering lukewarm water instead of piping hot, several issues might be at play.
First, check your water flow rate. These systems rely on a minimum flow to trigger the burner – too low, and the unit might not heat the water fully. A partially blocked showerhead or tap aerator could be the cause.
Another common culprit is a faulty temperature sensor or thermostat. If the system can’t accurately read the water temperature, it may shut off the burner too early. Similarly, mineral buildup on the heat exchanger can reduce heating efficiency, especially in hard water areas.
External temperatures can also affect performance. In winter, water entering the unit is colder and takes longer to heat, sometimes resulting in less-than-hot output.
If simple checks don’t solve it, call a licensed technician to inspect your unit – it could be a worn component that needs replacement.
Low or No Water Pressure
Low or no water pressure can prevent your instant gas hot water system from working properly. These systems rely on a steady flow to activate the burner and heat the water.
If pressure drops too low, here are a few things to check:
- Clogged filters or aerators: Built-up sediment or debris in your taps and showerheads can restrict water flow. Cleaning them may restore pressure.
- Partially closed valves: Check that the isolation valve on your hot water unit is fully open. Sometimes, it’s accidentally turned during maintenance.
- Pressure-reducing valve faults: If you have one installed, it may be malfunctioning and restricting flow more than it should.
- Leaks in the plumbing: A hidden leak can reduce pressure significantly. Look for damp spots, dripping pipes, or water stains.
- Municipal water supply issues: Occasionally, the issue is external and temporary – check with your water provider.
If pressure problems persist, contact a licensed plumber for a thorough inspection.
Error Codes Displayed on the Unit
Seeing error codes flash on your instant gas hot water system? These codes are the system’s way of telling you something’s wrong. While they can seem confusing, they often point directly to the issue.
Here are some common codes and what they might mean:
- Error 11 – Ignition failure: The system isn’t lighting the burner. Check the gas supply and power.
- Error 12 – Flame loss: The burner lit, then went out. Could be due to gas flow or venting problems.
- Error 29 – Blocked flue or heat exchanger: This may require cleaning or professional service.
- Error 61 – Fan failure: The fan may be blocked or damaged, affecting airflow.
- Error 99 – General system fault: This can mean several things and usually needs a technician’s help.
Always refer to your unit’s manual for code definitions, and if in doubt, call a licensed technician for expert support.
Strange Noises from the Unit
Hearing strange noises from your instant gas hot water system? Don’t ignore them – those sounds could be early warning signs of a problem.
A gurgling or bubbling sound may indicate a buildup of sediment or mineral deposits inside the heat exchanger. Over time, this can restrict water flow and reduce heating efficiency.
A banging or popping noise might point to delayed ignition, where gas builds up before lighting. This can be dangerous and should be checked by a professional right away. Whistling sounds could signal high water pressure or a partially blocked valve, both of which can strain the system.
Any unusual noise is worth investigating. While some sounds are relatively harmless, others may lead to serious damage if left unchecked.
Turn off the unit and book a technician to take a look. Catching these issues early can prevent bigger problems – and save you from an unexpected cold shower.
Gas Supply or Connection Problems
If your instant gas hot water system isn’t working at all, a problem with the gas supply or connections could be to blame. Here’s what to look for:
- Empty gas bottle (LPG systems): If you’re using bottled gas, check the gauge or try switching to a full cylinder.
- Gas meter turned off: Make sure the main gas meter valve is open. It may have been shut off during maintenance or an emergency.
- Gas leak detected: If you smell gas or suspect a leak, turn off the supply immediately and call a licensed gas fitter.
- Blocked gas line: Debris or damage in the gas line can stop fuel from reaching your hot water unit.
- Poor gas pressure: Low or inconsistent pressure can prevent proper ignition or heating.
Never try to repair gas issues yourself. For safety’s sake, always call a licensed professional to inspect and fix gas-related faults.
When to Call a Licensed Technician
Sometimes, a quick fix – like cleaning a showerhead or checking the gas supply – can get your hot water flowing again. But if you’ve tried the basics and still don’t have reliable hot water, it’s time to call in a licensed technician.
Persistent issues like error codes that keep coming back, lukewarm water despite high settings, or strange smells and noises from the unit are clear signs that something deeper is wrong.
A licensed plumber or gas fitter has the tools and training to safely diagnose and repair faults, whether it’s a faulty sensor, blocked burner, or gas pressure issue. Never attempt to fix internal components or gas connections yourself – it’s not only dangerous but could void your warranty.
If your system is older or hasn’t been serviced in a while, regular professional maintenance can also help prevent future issues. A trained technician ensures your unit runs safely, efficiently and reliably.
Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See our Terms & Conditions here.
FAQs About Instant Gas HWS Not Working
Do you have any questions about your instant gas hot water system not working? If so, we’ve got answers to the most commonly asked questions right here.
If you’re getting no hot water, the issue could be with the gas supply, ignition system, or water flow. Check that your gas meter or LPG bottle is on, the pilot light is working (if your system has one), and the water pressure is strong enough to activate the unit. If everything looks fine and it’s still not working, it’s best to call a licensed technician.
Lukewarm water can be caused by a partially blocked heat exchanger, a faulty thermostat, or insufficient flow rate. Start by checking taps and showerheads for blockages. If that doesn’t help, your system might need professional servicing.
Some error codes point to simple issues like low gas or water flow. Try resetting the unit and checking your manual. For persistent or serious codes, call a licensed plumber or gas fitter.
