Hot water
Hot water is one our home essentials. However, with rising energy prices, it pays to consider how you can get better energy efficiency out of your hot water heating.
By making some small changes you can create savings.
On this page:
Your energy spend
The hot water system in your house uses 29 %, on average, of your annual energy bill, making it an obvious place to start looking for savings.
Electric storage cylinder
The most common form of water heating is with electric storage cylinders.
Newer, electric hot water cylinders, installed post 2002 will be A-grade and well insulated. Cylinders older than that are likely to be C or D grade or uninsulated.
Insulation needs
Check to see if your cylinder has an A-grade sticker on it. Even if it does, the first metre of hot water pipe near the cylinder still needs to be wrapped with insulation.
If the cylinder is not an A-grade, it probably feels warm to the touch. Invest in a cylinder wrap. It will repay itself in energy savings and you can still use the hot water cupboard to air clothes and linen.
To find out how to install a wrap go to Hot water cylinder wraps.
Other hot water system options
Solar water heating systems
Solar water heating uses the sun's rays to heat water, which is stored in a standard hot water cylinder for later use.
A well designed and installed solar water heating system can use the suns energy to provide up to 75% of your hot water every year. When the sun cannot heat enough water to meet your household needs, the heat supply is boosted by electricity, gas, or a wet back system.
It is worth considering solar water heating, if your household uses a lot of hot water, and if you are setting up to reduce your living costs in retirement.
Heat pump water heaters
Heat pump water heaters are another product on the market and are a form of indirect solar water heating. The sun heats the air around your home each day, and a heat pump water heater shifts some of this heat from the outside air into you hot water. They generally work as well, if not better than solar water heaters, supplying on average $3 of hot water for every $1 of electricity they use.
Heat pump water heaters are also effective in situations where solar water heating is not suitable, such as:
- houses that don’t get direct sun during the day, or
- a house where it would be particularly expensive to install a solar hot water system.
Find out more information about heat pump water heaters
Gas water heaters
There are several gas water heating options that can use natural gas (gas mains) or bottled LPG. These include continuous flow gas heaters, and gas hot water cylinders. Continuous flow gas heaters remove the potential heat losses from a cylinder, are up to 95% efficient (95 cents worth of hot water for every dollar of gas used), and can have the added benefit of freeing up some storage space in your house if a cylinder is removed.
Gas hot water cylinders can go inside out outside your house. If considering a gas hot water cylinder, condensing systems are the most efficient type but do have to be located outside your house.
Wetback systems
Many wood or pellet fires, ranges or burner systems can have wet backs fitted to them. A wetback is a pipe arrangement the fits in the back of the firebox and uses some of the heat from the fire to heat water. It is important to remember that if you add a wetback to a new or existing burner, you will get less heat in the room than you would without the wetback.
The type and location of your hot water cylinder can often determine if you can fit or use a wetback, so check with the fire manufacturer and a plumber.
Take action
Install a hot cylinder wrap
An $80 cylinder wrap can cut your power bill by around $20 per year if you have an A-grade cylinder, and by up to $140 a year if your cylinder is C or D grade.
Find out more about solar water heating
Visit EECA’s Solar Water Heating website – www.energywise.govt.nz/solar
The site provides expert advice on:
- solar heating options for your home
- financial help
- building consent requirements
- accredited solar water heating suppliers.
Solar water heating grants
If you are a homeowner or landlord, you may be eligible for a grant towards installing a solar water heating package.
Visit EECA’s Solar Water Heating website for more information – www.energywise.govt.nz/solar
Household hot water saving tips
Check for the following around your home:
1. Outside drips.
If the vent pipe in the roof or on an outside wall is dripping, you will be losing heat. Your plumber may need to adjust the pressure-reducing valve.
2. Check your shower flow.
You may need a more water-efficient showerhead. Low flow showerheads give a good shower but use around half the water of a normal showerhead. They cost roughly $40-100 and can cut hot water bills by up to $1000 per year (a family using the shower for 40 minutes a day).
To check, run the shower at normal temperature. If it fills a 2-litre container in less than 12 seconds, you could save a lot of money by using a more efficient showerhead. These are available from hardware and plumbing stores.
3. Check the hot water temperature.
Older cylinder thermostats are not that accurate so you need to find the tap nearest to the cylinder and run it for at least 30 seconds before measuring the temperature. The temperature at the tap should be 55˚C (not less than 60˚C at the thermostat) . If it isn't, then the thermostat needs adjusting. In most cases, you will need to get an electrician to do this. Recheck the temperature next day after changing the thermostat.
4. Check your hot water cylinder.
If it is warm to touch, it probably needs an insulation wrap, available from hardware stores. Wrap the cylinder pipes that you can see in your hot water cupboard or the first metre above the cylinder with insulation or lagging, which is also available from hardware stores. You can only wrap electric hot water cylinders.
5. Fix leaky hot water taps.
A hot water tap dripping once a second can add $18 - 20 a year to your electricity bill.
More information:
- Getting warmer by degrees brochure. (PDF 1.3 MB) [EECA publication.]
- $ave on your power bill. (PDF 1MB) [Joint Department of Building and Housing Consumer publication.]
- Savings around the home. [Consumers’ Institute website.]
- Useful information on hot water and DYI tips at Home maintenance [Consumer Build website.]