So what are my options?

Solar water heating

Solar hot water heaters uses the free, unlimited energy of the sun. A well-installed system should be able to deliver up to 75% of hot water heating over the year, in most parts of the country. However, the concept of solar hot water heating has a few challenges in New Zealand:

• A high initial cost compared with other water-heating options

• Difficulty in ensuring the system is designed and installed correctly

• Some initial learning required to read and manage the interface

• Annual maintenance required

However, there are situations where solar is worth the investment:

• When used in conjunction with a wetback on a wood or pellet burner used as a primary space heating source over the colder months.

• When used as a very simple pre-heater with no controllers, or pumps, and plumbed into the pipe feeding into your water-heating cylinder.

• A self-contained heating system that doesn’t rely on the grid and exposure to power failures.

To maintain a hot water supply when the sun doesn't shine, solar hot water systems usually have backup heating – so you will still need to consider the pros and cons of other water heating systems too.

We are registered solar water installers so we recommend getting in touch to talk about your options and arrange a quote. To learn more in the meantime, you can also check out this online resource: Solar hot water options 

Heat pump water heating

Heat pumps use electricity far more efficiently than ordinary electric water heaters. They are usually used for space heating, but some are designed to heat water.

They work by extracting heat from the air outside, using a process that's like a refrigerator working in reverse.

There are two main types of systems – an all-in-one system where the heat pump is part of the hot water cylinder, and a split system where the heat pump is located outside and the hot water cylinder (which can be a modern electric cylinder) is located inside the house.

Consumer NZ research shows that a well specified and installed heat-pump water heater would reduce your hot water bill by two-thirds over standard electric water heating. Although heat pump hot water systems are more expensive to purchase than a standard electric hot water cylinder, their efficient operating costs mean that they are a great long-term investment.

Heat pumps work most efficiently at warmer outside temperatures (above 6-7°C) at which they are up to 2-3 times better than standard electric hot water cylinders. However, they lose efficiency as the temperature outside gets lower, so they are less efficient in winter.

Ask your heat pump supplier for the heat output figures at an external air temperature of 2°C – the higher the figure the better. They are particularly suitable for temperate to warm climates like here in Hawke’s Bay. And ideally can’t be located under a shaded roof.

New heat pumps have ozone-friendly gases. However, in some older heat pumps, the gas used to extract heat is harmful to the ozone layer if it escapes. Because of this, old heat pumps should be disposed of carefully – contact your local landfill for advice on how to do this.

It’s worth choosing your system carefully as some are better than others. Consumer NZ has tested some of the main systems available and found that the most efficient clearly outperformed the other systems. This was particularly the case at lower temperatures.

Hot water heat pumps can be noisy. We will give you advice on the best place to install the external unit - ideally away from bedrooms (yours – and your neighbours!).

Wetbacks

A wetback is a useful way to heat water in winter if you are replacing or installing a wood or pellet burner near your hot water cylinder. Ideally, the hot water cylinder should be located as close as possible to the wood or pellet burner to minimise the heat loss through the pipes. Larger diameter water pipes (25mm) are recommended.

Wetbacks can complement solar hot water, particularly to ensure year-round hot water during cooler months in Hawke’s Bay.

Wetbacks are also a great option when the power goes down - something we Hawke’s Bay people know only too well is a genuine risk factor, particularly if the grid failure happens during winter.

Many councils have regional clean air plans which strictly regulate the use of wood and pellet burners. The Ministry for the Environment has a list of Authorised woodburners on the Ministry for the Environment website lists the woodburners that meet New Zealand's air quality standards.

Gas/LPG water heating

Gas or LPG water heating includes hot water cylinders and instant gas hot water systems.

Gas hot water storage systems have a quicker heat recovery time than a comparable electric hot water cylinder.

Gas cylinders need to be located in a well ventilated area and flued to remove exhaust gases. This can lead to long pipe runs. Heat losses from gas hot water cylinders are higher than electric cylinders. It’s not safe to put a hot water cylinder wrap on a gas cylinder.

Find our more about gas hot water heating here on the really useful SMARTHOMES WEBSITE then get in touch.

Instant gas hot water systems provide continuous hot water that never goes cold, as the water is heated as it passes through the heater. Gas is only used when a hot water tap is turned on.

There is no storage cylinder, which means there are no energy losses from keeping water in a tank hot. Systems can be up to 95 percent efficient. The water temperature is set at a control panel reducing the risk of scalding.

If you're looking at an instant gas hot water system, look for one with automatic ignition not one with a pilot light. Pilot lights use gas even when the water is not being heated.

Electric water heating

Most New Zealand homes have an electric hot water cylinder. Older cylinders tend to be very small and low pressure, whereas modern electric hot water cylinders are high pressure/mains pressure cylinders. Most modern cylinders are 180 litres or bigger.

Older hot water cylinders are often poorly insulated, leading to heat loss. Electric hot water systems that are less than “A” grade insulated are worth wrapping with more insulation. If you do insulate them, they must be entirely insulated, otherwise the thermal benefit will be minimal.

Hot water cylinders and pipes has more information.

Instant electric water heaters are more energy efficient because they heat water only when it is used, eliminating standing heat losses from hot water sitting in storage cylinders and hot water pipes. However, they do have two drawbacks:

• Typically used when electricity is charged at the peak rate.

• Requires separate heavy-duty wiring for large flow rates.

They are therefore best used as a supplementary system where the outlet is a long way from the main hot water system (eg for washbasins or showers).