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When it comes to hot water in your home, you’ve likely taken it for granted on more than one occasion (we know we have!).

But what happens when your gas hot water isn’t working like it should and may need some repairs? We have put together some of the more common instant gas hot water system problems that can arise if you have an instantaneous gas hot water system.

What is an instant gas hot water system?

An instant gas hot water system has a range of names, including:

  • Tankless gas hot water system
  • Instantaneous gas hot water system
  • Continuous flow gas hot water system
  • On-demand gas hot water system

They are generally quite small and are located on the wall, heating water as needed instead of heating and then storing it. They are also one of the most efficient, if not the most efficient, hot water systems available.

How does an instant gas hot water system work?

Instantaneous gas hot water systems, as their name suggests, run on gas and function by propelling cold water through a pipe made of copper – known as a heat exchanger – that has heat applied to it directly.

energy rating gas instantaneous system

Instant gas hot water system. Image courtesy of Energy Rating.

When you turn on a hot water tap, a flow sensor is set off in your instant gas hot water system and the heating commences. This triggers a gas burner and the required amount of water is heated to the temperature that is needed and flows to your tap. Then, when you turn your tap off, your hot water system turns off too!

The most common instant gas hot water system problems

The pilot light won’t ignite

If you are finding that your water heater pilot light won’t ignite, remember that instant systems need moderate to high water flow to ignite the pilot light. Therefore, run your tap on high for a few minutes and see if this ignites the pilot light.

Sporadic hot and cold water

Having intermittent hot and cold water is quite a common problem with instantaneous systems. This can be caused by a range of things including:

  • The diaphragm on the gas meter could be faulty.
  • Not enough gas may be getting to your hot water system (which can be caused by an under-sized gas bottle).
  • You may have a faulty showerhead or a restrictor which may be affecting a taps’ ability to be registered as a ‘hot water’ tap.
  • Your system might be suffering from low hot water pressure.

Lukewarm water

Another issue that can arise is that of lukewarm water coming through the pipes, instead of hot water. This can be caused by a faulty thermostat or the diaphragm may need replacing.

Less water production

If you are finding that your hot water system is producing less water than it should, or at a lower water pressure than before, this can be caused by:

  • The strainer valve on the cold inlet may be blocked.
  • The thermostat may be broken or faulty

If water is also coming out at a lower pressure, this can be related to the pilot light. Remember though, instantaneous units supply hot water at a lower pressure than storage systems do!

No hot water at all

Finally, if you do not have any hot water there are a few things you can check before calling in a hot water plumber.

  1. Check a stovetop or other gas appliance to see if this still has gas flowing to it. If it does, the gas supply isn’t the problem – if it doesn’t, you’ve hopefully found your issue. If you find that there isn’t any gas flowing to other appliances, check your gas valve meter and call your local utility provider for more assistance.
  2. Double-check that the continuous flow is plugged into its electrical socket.
  3. If your system has a controller, check it is on and the temperature is set to the appropriate level.

Who does see about instant gas hot water system problems?

A qualified professional! Ensuring that you speak to an experienced gas fitter is crucial to receiving the best outcome for everyone – it also ensures that your insurance/warranty isn’t voided (which can happen if you complete the works yourself) and the job will get done right the first time. Give Brisbane Plumbing and Drainage a call on 1300 616 203 and we can help.