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How to reduce the amount of energy your hot water system burns through

Posted , updated 
A wooden thermometer climbs to 40 degrees Celsius.
Hot water systems chew use a lot of energy, but you don't need to have cold showers to cut back.(Pixabay: Gerd Altmann)

It's estimated 21 per cent of the energy used in the average Australian home is chewed up by heating water, but it doesn't have to be that way.

There are a few simple things you can do to cut down on the energy your hot water system uses.

How to adjust a hot water system thermostat

You have to be careful with hot water systems, because tinkering with them can be dangerous.

"There's only certain things you can do on your own, as far as doing anything where you need tools, you're best to get a plumber in," Ezy-Plumb managing director Petros Ttofari says.

But if your hot water system is running at a higher temperature than it needs to be, it's using more energy than it needs to — and you might be able to turn the thermostat down a little.

Every hot water system is a little different, some will have a thermostat you can adjust without having to break out a screwdriver.

"If you open the access panel at the bottom, there'll be a dial in front of you with numbers on it," Mr Ttofari says.

"The higher the number is on the dial, the higher the temperature.

"It's just a matter of turning the dial to whatever setting you want.

"I wouldn't recommend people go to too low a setting, because it needs to be hot enough to prevent bacteria growing in [the tank]."

But you have to be especially careful with electric hot water systems and make sure you're not removing any panels that have an electrical warning on them — that's what you need to call a plumber for.

The inside of the temperature regulator in a hot water system.
Most systems can be adjusted by the twist of a dial.(ABC News)

How hot should it be?

That depends on what system you have.

There are two main types of hot water systems:

  • Storage: water is heated and stored in a tank ready for use
  • Continuous flow: heats water only when required — there's no storage tank

If you've got a storage hot water system, you want to set the temperature to 60 degrees, according to the Federal Government's Your Home sustainability guide.

That's because you need it to be at least 60 degrees to stop the growth of Legionella bacteria, but any higher than that means energy is being used unnecessarily.

A continuous flow system doesn't need to be set as high as it doesn't store the water, so it should be no higher than 50 degrees.

Insulate your pipes

Sustainable Living Tasmania says the warmth that radiates from pipes coming from your hot water unit is wasted heat, as it's "lost to its surrounds".

"A poorly insulated system located outdoors can lose up to 3 kilowatt-hours per day, which costs $185 per year," the organisation's website says.

"Adding insulation is a cheap and easy DIY job that can slash these loses."

Think of it as a jacket for a pipe.

"It does hold the heat in better," Mr Ttofari said.

"That's something that a homeowner can do if there's access to the pipe or you want to crawl underneath the house.

"It is relatively safe; the only dangerous thing is that the pipes may be quite hot.

"There's a scalding risk if you're touching the pipes, but you could get away with wearing gloves."

A hot water system with black foam wrapping around the pipes.
Insulating your hot water pipes can prevent the unnecessary loss of heat, saving energy and money.(Tasmania Energy Saving Projects Resource)

Sustainability Victoria recommends closed-cell rubber insulation, but your local hardware should have some good options for your pipes.

The sleeve should sit snugly, but you can fix it in place with zip ties or duct tape.

All exposed hot water pipes can be insulated if they're accessible but the first 2 metres coming from the hot water unit the most critical sections, according to the Tasmania Energy Saving Projects Resource.

Chris Barnes, Choice magazine's product category manager for households, says pipe insulation probably should be common practice for new builds.

"I believe it does make a difference, especially in cold areas where you've got a long run for a hot water pipe or if your house doesn't have great insulation otherwise," he said.

You can even insulate some of the trickier hot water system appendages, like the relief valve.

There's an Australian-designed cover called a Valve Cosy, which clips into place around the valve. The makers say the cover can reduce heat loss by about 5 per cent.

Maintain your system

Mr Ttofari says it's best to have your system serviced every two years.

But you can help to keep your system running smoothly with a quick biannual flick of a lever.

"With the storage units, every six months you need to release the relief valve, that just helps with the longevity of the unit," Mr Ttofari said.

"You just lift it up for about 10 seconds then put it down again."

A storage tank unit usually lasts between 10 and 15 years, while continuous flow units can last a little longer — roughly 15 to 20 years.

A pressure relief valve attached to a hot water system.
Even the relief valve can be insulated.(ABC News)

Do your research before it's too late

Most of us aren't in the market for a hot water system, but Mr Barnes says that's exactly why we should be thinking about it now.

"They tend to do their job and then suddenly die and that's why it's good to plan ahead," Mr Barnes says.

"Because when the hot water's out, you're not shopping around anymore."

Mr Barnes says it's best to do your research. Having compared a bunch of different systems for a Choice buying guide, he knows there's a lot of options out there.

He says a solar hot water system was probably the best option for long-term energy and financial savings because you're consuming less energy to heat your water.

But it's important to be realistic about your specific needs.

"Try to match the hot water system to your household size and usage," Mr Barnes says.

"There's no point having a huge water tank if it's just one or two people in the house.

"So for smaller households, a continuous flow can be a good idea because you're only heating the water as you use it.

"If you're in a family, a storage tank is a more sensible option."

That option may support the whole household, but Mr Barnes says there may be some times when mixing and matching was an option.

"A storage standard system might support most of the household, but if you've got an upstairs area too far away from the tank then you might put in a simple continuous hot water system to support that one."

Cut back on your water usage

Using less hot water means your system needs to heat less water.

More than half of your hot water is used in the bathroom, roughly a third is used in the laundry and the kitchen accounts for the rest.

The Your Home guide says the most effective way to cut back is by installing water-efficient showerheads.

A showerhead with at least a three-star efficiency rating can reduce your shower time water usage by about half.

It also recommends using cold water instead of hot water as much as possible, especially when running the washing machine and rinsing dirty dishes before they go in the dishwasher.

The Your House website also recommends keeping mixer taps on the cold position when they're not in use.

A white sink with an ornate silver mixer tap with a white handle. The tap is in the cold position.
Even the position you leave your tap in can make a difference.(ABC News)

"Mixer taps can increase hot water use as they mix hot and cold water together in the centre position," the website says.

"In bathrooms or other locations with long pipe runs to the tap, 1 or more litres of hot water is wasted in the pipe and only cold water comes out.

"If you do not need hot water or need it only for short uses, move the mixer tap to the cold position."

And if you notice any drips, fix those as soon as you can.

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