How Do Continuous Flow Hot Water Systems Work

  • William Demirdonder
  • December 26, 2020
  • No comments
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Continuous hot water systems heat the water as it is needed by passing cold water through a heat exchanger device, igniting a gas burner, or switching on an electric element heating the water. Continuous hot water systems are very economical because water is only heated as required which means there is no additional cost to ‘storing’ hot water.

When a hot water tap is turned on, an electronic sensor starts the heating element. In a continuous flow gas system, it triggers an actual burner and in an electric system it triggers an electric heating element. As water passes through the unit, it is heated to the preset temperature and then fed straight to your tap. When the tap is turned off, the unit stops the heating process.

Continuous flow hot water systems work by pushing cold water through copper piping and applying heat directly to these pipes. When a hot tap is turned on, a flow sensor triggers and starts the heating. In a continuous flow gas system, it triggers a burner and in an electric system it triggers a heating element. The water is heated to the necessary temperature and then fed straight to your tap. When the tap is turned off, the unit shuts off too.


As no water is stored, there is no heat loss from a tank or any need to keep a body of water at a consistent temperature. These units only operate when the hot tap is turned on and provide continuous hot water for as long as the tap is open.

Gas-based continuous flow hot water systems are among the most efficient domestic water heaters available. Electric continuous flow systems use less power than their storage tank counterparts, but still produce more greenhouse gas (CO2) than a gas storage system and because they operate on demand, this will often be during peak times.


Although they are called ‘instantaneous’ systems, current model continuous flow hot water systems are generally less efficient than tank storage hot water systems in terms of how much water they waste. This is mainly because the water needs to be running for the heater to start, but also because it takes some time for the water to reach its peak temperature.


Some water is also wasted while hot water travels from the water heater to the tap – although this problem is common to both tank storage and continuous flow water heaters and can be somewhat overcome using a cold water diverter. Studies are currently underway to decide if and how to include continuous flow water heaters in the Australian Water Efficiency Labelling and Standards scheme (WELS).



More and more these days people are switching to a continuous flow hot water system because of its efficiency and guarantee of all-day-and-night hot water.

There’s nothing worse than getting out of bed and into the shower only to discover that someone’s used up all the hot water – or maybe coming back from a weekend away and having to wait for hours for the hot water tank to heat itself back up again.

Continuous flow hot water is replacing traditional hot water storage systems all around the country because of situations just like this. Now you can install one simple system that offers continuous hot water, day in and day out.

Best of all, because a continuous hot water system only heats your water as and when you need it, you won’t waste money reheating a large storage tank again and again when you don’t need it. That means your energy bill is going to look a little lighter, and you’ll also be being a bit kinder to the environment


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