Posted by Luciana Lawe Davies 09/08/2022

Hot water is one of the finer luxuries in life we don’t miss until, suddenly, we are without it. It happens all the time, maybe you were the last one to jump in the shower, or someone in your house has decided to do the washing up just as you were running a bath. There’s nothing quite like the shock of the water running artic midstream, leaving you frozen with cold, and the realisation there’s no more hot water.

This is where instantaneous hot water systems come into play. By only heating the water you use, instantaneous hot water systems ensure you never run out of hot water. Even better, they eliminate the need for paying extra for hot water you don’t use and help cut down on the family energy budget. If you’re currently using a storage system or looking to change your hot water unit, you should consider an instantaneous hot water system. Canstar Blue has compiled a complete guide to instantaneous hot water systems, so you can understand why they may be a better choice for you.

Instantaneous hot water systems, also called continuous flow hot water systems, are tankless hot water systems that provide instant hot water through your taps. They function by using a heat exchanger, which is a coiled pipe heated either by gas flame or electricity, that heats the water as it flows through.

The water flows through the pipes cold, passes through the heat exchanger where it is warmed, and comes out the tap hot. An instantaneous hot water system can be installed inside or outside the home, depending on your existing setup.

Instantaneous hot water systems work differently to storage systems, which use hot water tanks.

A storage, or hot water tank, works by storing water in a reservoir and heating it either via a flame, or an electrical element. As water in the tank is used – like when someone has a shower – new, cold water passes in, is heated, and stored until needed. As hot water is lighter than cold water, it flows through the top of the tank into the hot water taps in your house, while cold water is topped up at the bottom of the tank. Each tank is equipped with a thermostat to ensure the water temperature remains consistent, and a pressure valve to prevent excess build-up. This system requires the water in the tank to be continually heated, even when it isn’t being used, which if you aren’t using a solar hot water system, can use a considerable amount of energy.

In comparison, instantaneous hot water isn’t stored anywhere. Instead, the water flows through the water pipes cold, is heated as it passes through a heat exchanger, and comes out through the tap as hot water. This system uses far less energy, as it only heats the water that is used.

Each system has its advantages and disadvantages, which we’ve outlined below.

Instantaneous gas hot water systems do need electricity, but not for heating the gas. Instead, electricity is used to power the thermostat which maintains the consistent temperature of the hot water, as well as the control panel, and any sensors related to appliance performance. This means if there is a power outage, your instant gas hot water system may not work, as it also relies on electricity to function.

Instant or continuous, hot water systems use less energy than storage hot water systems. This is because a storage hot water system uses high amounts of energy to keep large amounts of water hot over a long period of time.

Continuous hot water systems only heat water when the hot tap is turned on, which means they’re heating small amounts of water over a short period of time. This system saves a considerable amount of energy.

An instant hot water system only uses gas to heat water being used, so the amount of gas used is dependent on the amount of water flowing through the tap. While instantaneous hot water systems are the more energy-efficient alternative to storage systems, households who use a lot of hot water may incur higher-than-normal gas bills. To find out how much gas your hot water system is using, you will need to look at your gas bill.

The gift of instant hot water is a hard one to turn down, but before you rush out and buy the first system you see, there are a few things you need to take into account. Listed below are the top five considerations to have in mind when buying an instantaneous gas hot water system.

The cost of an instantaneous hot water system includes the price of the unit itself and the cost of installing it. If you’re replacing a hot water system that is already installed, you can expect to fork out anywhere upwards of $200. However, if you are installing a new system that requires additional equipment or repositioning your existing system, costs will be higher and depend on the installation location and suitability. Finally, if you are switching your system power from electric to gas, or vice versa, additional plumbing and electricity costs will also be incurred. Make sure to get a quote from your hot water system provider to understand the full cost of buying and installing an instantaneous hot water system.

Cost of instant hot water systems:

Instantaneous gas hot water systems have an excellent lifespan. Unlike their tank counterparts, they can last up to twenty years, which is nearly double that of a tank hot water system. An instant water system lasts longer because it uses a simple heating device and stores no water, which eliminates the build-up of rust and corrosion.

If you’re able to foot the buying and installation costs, investing in an instant hot water system is worth the price. Throughout its possible twenty-year lifetime, an instant hot water system will not only provide you with hot water every time you need it, but also reduce your energy bill and emissions – making it a smart choice if you love both the environment and steaming showers.

If you do choose to buy an instant hot water system, keep in mind they work best for smaller households, and you will have to invest in installation as well as the price of the unit itself.

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To our knowledge, all information in articles on the Canstar Blue website was correct at the time of publication. This information may have changed over time. Refer to the product fact sheet (or relevant similar documentation) before making any purchase decision. Canstar Blue's website terms and conditions apply.