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Should I install an instant hot water system?

Instant hot water systems

An instant hot water system, sometimes referred to as a continuous flow water heater, gives instant and endless hot water because there is no storage and heating cylinder, just a relatively small wall-mounted heating system. This system heats water only when you need it.

While the absence of a traditional hot water tank makes an instant hot water system a great option for smaller homes such as units and apartments, these systems are also ideal for larger premises.

How Do Instant Hot Water Systems Work?

The traditional storage cylinder heater stores a large amount of water and continually heats it to ensure it’s warm when required. That can be costly and wasteful because, when you turn on the hot water tap, you must wait for the cooled water to run through the pipes until the hot water appears. It also means that, your storage hot water cylinder is continually heating and cooling which uses expensive electricity.

With an instant hot water system, a flow sensor is triggered when you turn on the hot water tap. This switches on a gas burner or electric element which heats the water very quickly. As long as the hot water tap is on, water is continuously heated. Then, when the tap is turned off, the burner or heating element also turns off. In this way, you only heat the water as you use it.

Choosing a Hot Water System

Whether you are replacing hot water cylinders or need one repaired, or you are wanting a new hot water cylinder installation or instant hot water heating system, the Plumbworx team will provide expert plumbing advice on choosing the correct hot water system for your home or business.

How long should an instant hot water system last?

With proper installation and maintenance, an instant hot water system should easily last over ten years and usually a lot longer. On average, this makes them longer lasting than a hot water cylinder system.

Are instant hot water systems safe?

Most people would concede that instant hot water systems are safer than storage tank water heaters. First, there is no chance of a cylinder corroding and leaking. Or of it bursting because of pressure issues. Cylinder corrosion can also lead to rust and discolouration in the water which does not occur with an instant hot water system.

Cylinder systems also come with the risk of the stored water growing bacteria such as legionella – this is one reason why hot water cylinder thermostats are set to at least 60°C because, at this temperature, the bacteria cannot survive.

Finally, the water from an instant hot water system doesn’t need to be heated as high as cylinder water. Most systems will be set to 50°C.

Will an instant hot water system save me money?

Yes! While an instant hot water system is more expensive to install, once in place they will result in savings to the cost of both water and power that can be quite significant. This is because you are paying only for the water you use and there is no power wastage due to heat loss from a storage tank either.

And, as mentioned above, instant hot water systems also tend to last longer than storage tank systems.

If you’re still not sure if an instant hot water system is right for your home or business, contact a plumber who installs these systems. They will give you advice on the best system for your property.


Established in 2000, the Plumbworx team have over 85 years of experience between them – it’s that experience coupled with plumbing expertise that make us one of Auckland’s leading plumbing companies.

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