Hot water systems buying guide

01.Introduction

When a hot water system (HWS) goes – whether with a bang or a whimper, or even a flood – it tends to go suddenly. At that point you don’t have the luxury of carefully reviewing the available options (unless you love cold showers). Instead, you get a replacement of the same type wheeled in ASAP – and blissfully forget about it until next time.

However, water heating can account for a quarter of typical household energy use, so it’s worth reviewing your hot water usage well before your current system dies and checking out the alternatives – you may find a system that saves energy and money and is kinder to the environment.

New limits on electric HWS

For many people, replacing an old electric hot water system with a similar model is no longer an option. Standard electric systems produce around four tonnes of greenhouse gases per year (on average) – similar to an average sized car, and around three times as much as gas or solar HWS. To reduce this environmental impact, government regulations now limit the installation of electric HWS:

• Electric HWS can’t be installed in any new detached, terrace or town house, or any such existing property where there is access to piped natural gas (some exemptions apply).
• From 2012, this will apply to all existing detached, terrace or town houses.

You don’t need to replace a working electric HWS, but if you own a detached, terrace or town house, and it currently has an electric HWS, you need to consider a gas, solar or electric heat pump for your next replacement. Electric HWS are still available for apartments and other homes where gas, solar or heat pump systems aren’t feasible.

For more articles on saving energy, see EnergyCHOICE.

Which fuel?

The most common fuels used for water heating are gas and electricity.

• Electric water heaters that can heat water at any time of day are by far the most expensive option. Off-peak electric (which heat only when tariffs are lower) and gas systems have similar costs, depending on the tariffs you have to pay.
• Natural gas produces much less of the greenhouse gas carbon dioxide (CO₂) than electricity to heat the same amount of water. But it's not available everywhere.
• You can also get hot water from sun and air, which reduces CO₂ compared to conventional electric heaters, in most places.
• In areas where you can't get natural gas, liquid petroleum gas (LPG) is an alternative. But expect to pay about one-and-a-half to three times as much as for natural gas or electricity.

Which type?

There are two main types of water heater: storage and instantaneous. Instantaneous heaters heat the water instantly, while in storage heaters it's stored in a tank.