Hot water is a modern luxury that we often take for granted until it’s not there. If you have an instant gas hot water system, you’re accustomed to the convenience of on-demand hot water. However, like any appliance, these systems can encounter problems. Fear not! In this guide, we’ll explore common issues and provide practical tips on how to troubleshoot and solve them.

1. No Hot Water Flow

You turn on the tap, but there’s no hot water flowing.

Start by checking the gas supply. Ensure that the gas valve is open and that the pilot light is on. If the pilot light is out, relight it according to the manufacturer’s instructions. Additionally, check for any obstructions in the water filter or the unit’s water inlet.

2. Inconsistent Water Temperature

The water temperature fluctuates, making it challenging to enjoy a consistent shower.

This issue may stem from a faulty thermostat. Adjust the thermostat settings following the manufacturer’s guidelines. If the problem persists, there could be sediment buildup in the heat exchanger. Flushing the system can help resolve this. Refer to your unit’s manual for instructions on flushing and maintaining the heat exchanger.

3. Strange Noises

Unusual sounds, such as banging or gurgling, are coming from the water heater.

Noises could indicate air in the gas line or sediment buildup in the tank. Bleed the air from the gas line according to the manufacturer’s instructions. For sediment, flushing the tank may eliminate the noise. If the issue persists, consult a professional to inspect the unit for potential mechanical problems.

4. Water Leaks

There’s water pooling around the base of the water heater.

Inspect all connections, including the pressure relief valve, for leaks. Tighten any loose connections and replace faulty valves. If the leak persists, it could be a sign of a more severe issue, such as a corroded tank. In such cases, it’s best to contact a professional plumber or technician.

5. Pilot Light Issues

The pilot light won’t stay lit.

Check for a faulty thermocouple, which is a safety device that detects whether the pilot light is on. If it’s malfunctioning, it may shut off the gas supply. Replace the thermocouple if necessary, following the manufacturer’s instructions. Ensure that the pilot light flame is steady and blue. If it’s flickering or a different color, it might indicate a combustion issue, and you should seek professional help.

6. Low Water Pressure

The hot water pressure is lower than usual.

Low water pressure can be caused by various factors, including a clogged filter, sediment buildup, or issues with the water supply. Begin by checking and cleaning the water filter. If the problem persists, consult your unit’s manual for guidance on flushing the system and maintaining optimal water flow.

7. Foul Odors

The hot water has a strange, unpleasant odor.

Foul odors are often a result of bacteria in the tank. Disinfect the tank by flushing it with a hydrogen peroxide solution. Follow the manufacturer’s instructions on tank maintenance. If the odor persists, consider consulting a professional for a thorough inspection.

8. Ignition Problems

The ignition is not working correctly, leading to intermittent hot water supply.

Inspect the ignition system for dirt or damage. Clean the igniter and check for loose connections. If the problem persists, it may be a more complex issue requiring professional attention.


Maintaining your instant gas hot water system is crucial for ensuring a continuous and reliable supply of hot water. Regular inspections, cleaning, and following manufacturer guidelines for maintenance are key steps in preventing and addressing common issues. By understanding these tips and troubleshooting techniques, you can keep your hot water flowing efficiently and enjoy the comfort of a well-functioning gas hot water system.