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