Many of us don’t give much thought to how our water is heated – all that matters is that it’s nice and warm when it reaches the tap or show head. But the truth is there are a number of systems out there that use different methods for heating water. Systems may use gas, solar or electricity and may come in the form of storage tanks or you may have heard of hot water cylinders.

In New Zealand electric systems are one of the most popular choices for heating up water. Hot water cylinders work by using an electrical element in a tank that is insulated, the element which looks a bit like a coil or loop heats up the water in the tank to the temperature dictated by the thermostat (it works in a similar way to a kettle). Hot water cylinders have two tubes for transferring water, a cold tube to bring cold water into the tank and a hot tube to send water to taps or showerheads.

When the heating element is in use with electricity running through it, it creates heat which warms up the contents of the tank. This is different to gas heaters which rely on a heat exchanger, the electricity instead of heat the tank directly.


Benefits of hot water cylinders

One of the great benefits of hot water cylinders is that they are highly energy-efficient when they use an immersion element, especially when comparing them to gas heaters. More electric systems are about 90 percent more energy-efficient whilst gas heaters usually achieve a 60 percent rating. Electric options will usually attract slightly higher costs than the cost of natural gas.

In terms of speed and recovery however, gas models will usually outperform the average electric system which can take additional time to heat a similar volume of water.

One of the reasons that hot water cylinders have become very popular is become of the low cost to purchase and install them as well as their relative flexibility for placement. They can also be purchased with options to make them suitable for solar energy. It’s possible to purchase them with a thermostat to control the temperature which means your water heater will not go over a certain temperature which can save you money in the long run. If your home uses a boiler system then you’ll enjoy peace of mind because hot water cylinders are not connected to boilers and so you’ll still have access to hot water if your boiler stops working, gets damaged or breaks down. A properly insulated water heater can keep your water supply for many hours even after it has switched off and stopped heating water.  It’s possible to set your heater heat up in off-peak electricity times to help you conserve energy and costs. Most systems can be managed or easily switched on or off at the wall socket – they are great for energy efficiency and eco-conscious homeowners. The ability to turn them off is also for use when you’re away from home and do not need to heat up any water supply in the home whilst you’re away, this will prevent unnecessary use of energy.


What do you need to know about them?

So what sort of things should you keep in mind regarding electric systems? Here are a few important points:

  • Using electricity to heat water can be more expensive than using gas. In New Zealand, you can expect an electric system to use around 3 kilowatts per hour to heat water and most homes will need to heat water for a few hours each day.
  • It’s a good idea to have a thermostat installed, otherwise electric systems will heat water to unnecessarily high temperatures
  • Systems will need to be heated to at least 50 degrees Celsius to kill of any nasty bacteria.