Matamata Chronicle - - Advertising Feature -

A wood­burner is a cheap way to heat your home – if you can get free or cheap fire­wood.

De­liv­ery is usu­ally part of the price but this de­pends on dis­tance.

Open fires are in­ef­fi­cient (heat is lost up the chim­ney) and cause mas­sive pol­lu­tion for the heat they do pro­duce.

Tip: Buy fire­wood early – dur­ing spring or early sum­mer – and phone around for prices.

How clean?

Along with wind and hy­dro, wood is one of the few sus­tain­able car­bon­neu­tral home-heat­ing op­tions. But to get the most heat (and the least pol­lu­tion), it must be burned hot and in a spe­cially de­signed fire­box.

The fire­wood must also be dry and the pieces not too big (less than 11cm in di­am­e­ter).

Some wood­burn­ers can be used to heat wet­backs but this re­duces their ef­fi­ciency and may also over­heat the wa­ter.

Wood pel­lets

Wood pel­lets are used in burn­ers and also in boil­ers for cen­tral heat­ing.

The pel­lets are sold in 15kg or 20kg bags. Prices were gen­er­ally lower in the South Is­land.

If you’re about to buy a wood­burner, here’s what to con­sider.


Free­stand­ing mod­els are gen­er­ally the most ef­fi­cient (for a given fire­wood load, they re­turn the most heat to a room). They’re also the cheap­est to in­stall. But if you have an ex­ist­ing open fire­place, an in­sert model is most of­ten the way to go. Al­though in­sert mod­els are not as ef­fi­cient as free­standers, they’re way bet­ter than an open fire.

Choose a wood­burner with a heat out­put suit­able for your home. If you have a non-draughty wellinsu­lated home in the north of the North Is­land then 10kW should be plenty.

A larger house – or the same-sized but less-wellinsu­lated and draughty house – fur­ther south will re­quire more heat out­put. Think in terms of 12-14kW.

In non-open-plan houses there’s no point in over­heat­ing the lounge while the rest of the house stays cold. In­stall a heat­dis­tri­bu­tion sys­tem to help spread the heat through­out the house.

Con­vec­tor vs ra­di­ant

All wood­burn­ers both heat the air and ra­di­ate heat on to ob­jects that are within a few me­tres of them. But some wood­burn­ers are mar­keted as pre­dom­i­nantly one type or the other. It de­pends on the ex­ter­nal de­sign of the fire­box.

A con­vec­tor heater heats the air im­me­di­ately around it.

Hot air is lighter (less dense) – so it rises away from the heater and gets re­placed with cooler air which is in turn heated. This con­vec­tion air-cur­rent means that the warm­est air in the room ends up near the ceil­ing with the coolest air near the floor.

Con­vec­tor heaters are air warm­ers.

A ra­di­ant heater ‘‘shines’’ heat on to any­thing in its path.

That could be you if you’re near the fire, or fur­ni­ture within a few me­tres of the fire.

Tip: Con­vec­tors are best for well-in­su­lated non­draughty houses with low ceil­ings.

Ra­di­ant-type mod­els suit older and less-well in­su­lated (or draughty) houses with higher ceil­ings.


The con­trols should op­er­ate smoothly, and it should be rel­a­tively easy to clean the outer sur­faces and empty the fire­box.

Flue sys­tem

The flue must have a larger di­am­e­ter outer shield around it where it passes through the ceil­ing and at­tic space.

The lower the par­tic­u­late emis­sions from your fire, the less of a health haz­ard you’ll be caus­ing.

You can find this out from the wood­burner’s com­pli­ance plate.


A wet­back uses cop­per pipes to cir­cu­late wa­ter from the wood­burner to the hot-wa­ter cylin­der and back.

They’re ex­pen­sive to in­stall and the hot wa­ter cylin­der needs to be placed rea­son­ably close to the burner.

Safety guards

Wood­burner sur­faces can get very hot and can be a dan­ger to small chil­dren. Pro­tec­tive guards are avail­able, and highly rec­om­mended.

Build­ing con­sent

Be­fore you buy a wood­burner, make sure your lo­cal au­thor­ity will al­low you to in­stall the model you want: some coun­cils will only al­low in­stal­la­tion of mod­els from their rec­om­mended list.


A poor in­stal­la­tion job can ruin the heat­ing and emis­sions per­for­mance of the best of wood­burn­ers. Check that your in­staller has New Zealand Home Heat­ing As­so­ci­a­tion cer­ti­fi­ca­tion or is oth­er­wise suit­ably ex­pe­ri­enced.

Heat trans­fer

A heat-trans­fer kit usu­ally re­moves warm air from the lounge and ducts it to a colder part of the house. Al­ter­na­tively it can be set up to duct cold air from else­where in the house and de­liver it to the lounge for heat­ing. Ei­ther way the doors must be left open or ajar so that the air can cir­cu­late and even out the tem­per­a­tures. changes that are out of the house­holder’s con­trol.

How clean?

Nat­u­ral gas is clean­burn­ing for pol­lu­tants, but it’s a fos­sil fuel. Burn­ing it adds the green­house gas car­bon diox­ide to the en­vi­ron­ment. chil­dren, preg­nant women and peo­ple with asthma or heart dis­ease – and high lev­els of it can be fa­tal to any­one.

For this rea­son an un­flued heater should only be used in rooms with good ven­ti­la­tion and should never be used in bed­rooms.

Diesel is an at­mo­spheric pol­lu­tant and a non­re­new­able re­source.

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