Wa­ter heat­ing op­tions

Matamata Chronicle - - Heating -

Most New Zealand homes use elec­tric hot wa­ter cylin­ders. Oth­ers use gas or LPG hot wa­ter cylin­ders or in­stant gas hot wa­ter sys­tems (which heat wa­ter as you need it). Both gas and elec­tric­ity pro­duce green­house gas emis­sions – but gas pro­duces less than elec­tric­ity when the lat­ter is gen­er­ated by burn­ing fos­sil fu­els.

In­stant elec­tric wa­ter heaters are some­times used for wash­basins or show­ers and are en­ergy efficient be­cause they heat wa­ter where is is used, elim­i­nat­ing heat loss from stor­age cylin­ders and hot wa­ter pipes. Draw­backs with in­stant elec­tric hot wa­ter sys­tems are that they are typ­i­cally used when elec­tric­ity is charged at the peak rate and they also re­quire sep­a­rate wiring for large flow-rates.

In­stant gas hot wa­ter sys­tems pro­vide con­tin­u­ous hot wa­ter that never goes cold, as the wa­ter is heated as it flows to the tap. Gas is only used when your 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 efficient and wa­ter tem­per­a­ture is set at a con­trol panel re­duc­ing the risk of burns.

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.

This is the most en­ergy-efficient wa­ter heat­ing op­tion – the sun’s en­ergy is free, un­lim­ited and non-pol­lut­ing. For many house­holds, it is also the most eco­nom­i­cal – con­vert­ing to so­lar can pay for it­self over time through lower en­ergy bills.

Con­vert­ing to so­lar is par­tic­u­larly worth­while for larger house­holds, house­holds that use a lot of wa­ter and for homes in sun­nier ar­eas.

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.

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.

Man­u­fac­tur­ers of­ten claim heat pumps give three times the heat.

Heat pumps lose ef­fi­ciency as the tem­per­a­ture out­side gets lower, so they are less efficient in win­ter.

Ask sup­pli­ers for the heat out­put fig­ures

A wet­back is a use­ful way to heat wa­ter in win­ter if you have a wood­burner and a re­li­able source of dry, un­treated wood.

You can also use a wet­back with an open fire but open fires are very in­ef­fi­cient.

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