How to Make an Efficient Heating System Even Greener

A pre-heat system warms the otherwise cold water coming into the boiler. This reduces the amount of fuel the boiler needs to burn to heat the water to the desired level and can also reduce the delay that you experience while waiting for hot water to reach the taps. There are two types of pre-heat system:

• Solar water pre-heat: This option uses a standard solar hot-water system to warm the water before it's fed into the combi boiler. It's quite an expensive setup to install and you'll need a tank as well as a boiler. Also, note that it will only work with certain boilers, so be sure to check with your boiler manufacturer before ordering.
• Zenex Gas Saver: This is a more compact solution - effectively a "top box" that bolts on to a combi boiler. It extracts otherwise wasted energy from gases exiting the flue, using it to pre-heat the incoming cold water feed, and makes the boiler operate more efficiently. The box costs $575 (plus installation costs) but it can reduce gas use by around a fifth. The Gas Saver can currently be used with all Alpha and Veissmann boilers and many others besides. 

Depending on where your boiler or hot water tank is situated in relation to your taps, it can take up to a minute to actually get any warm water out. In this time you will waste up to twelve liters of water and a whole lot of gas or oil. Moreover, once you turn off the tap, warm water remains in the pipe. If you need hot water again soon afterwards, this water will still be warm, but if it's left for an hour or so then its thermal energy will usually have dissipated and you'll have to wait another minute for hot water. For this reason it pays to insulate the pipes that take the water from your boiler to your taps. This is best done when the pipes are installed, as some of them will be inaccessible once the system is complete. But even for existing heating set-ups it's possible to reduce thermal waste by adding inexpensive lagging to exposed hot-water pipes in lofts, cupboards and other accessible areas.