Wood burners

Modern wood burners are highly energy efficient, produce limited air pollution and use a form of renewable energy - so are essentially carbon neutral.

Pros and cons of modern wood burners

  • They’re relatively cheap to run - even if you have to buy firewood.
  • Wood is renewable and sustainable - and New Zealand has extensive areas of forestry.
  • Burning wood from sustainable forests is carbon neutral - while trees are growing, they capture carbon dioxide from the air. This carbon dioxide is released either when the wood is burnt, or when the tree dies and rots. While some emissions are produced in the transporting and processing of the wood, this is only a very small amount per unit of heat produced.
  • Wood burners work during power cuts – many free-standing models can be used for cooking as well as heating.
  • Some wood burners can be equipped with a wetback system to heat water - check with your supplier about this option.

Wood burner checklist

  • Insulate first - starting with your ceiling and floor. This will make your house easier and cheaper to heat properly.
  • Make sure you have a sheltered space to store firewood - exposed to some wind but protected from the rain.
  • Get a building consent - from your local council, before you install a solid fuel burner. Check with them to find out if they have any extra requirements for solid fuel burners. If an illegally installed wood-burner causes a fire, it may invalidate your insurance cover.
  • Choose an authorised wood burner - burners installed on properties less than 2 hectares in size must meet certain emissions and efficiency standards. Check out the Ministry for the Environment's list of authorised wood burners via the link below. Buy the most-efficient wood burner that suits your needs.
  • Free-standing or insert model? - Freestanding wood burners tend to be more efficient and cheaper to install. However, if you want to replace an existing open fire, an insert model can be fitted into the same space and will be much more efficient than the open fire.
  • Work out what size you need - wood burners need to be carefully matched to the room you want to heat. Ask your heating supplier to advise you on the right size heater for your needs.
  • Decide whether you want more radiant or convective heat - wood burners release their heat through a combination of heat radiation (which heats objects) and convection (which heats air). The amount of each varies from model to model.
    • Radiant heat - wood burners that produce mostly radiant heat make the room feel warmer than the air actually is. This makes them particularly suitable for large rooms with high ceilings and for rooms where you have poor insulation and draught issues.
    • Convective heat - convective wood burners heat the air around them, which then rises to the ceiling. This means you get less heat in the bottom part of your room, unless you use a ceiling fan to mix up the hotter and cooler layers of air. Convective heat makes it easier to move some of the warm air to other parts of your home with a heat transfer kit.
  • Wetback models - use the heat of the wood burner to heat hot water, by circulating water between the wood burner and the hot water cylinder through pipes. The hot water cylinder needs to be placed reasonably close to the burner. A wetback can be cost-effective if you use the woodburner daily for extended periods in winter, and if your household uses a reasonable amount of hot water. Note that some wood burners with wetback option only meet emissions and efficiency standards without the wetback fitted – check with the supplier.
  • Use a certified installer - quality installation is fundamental to your wood burner's performance and safety. We recommend that you have your wood burner installed by a Solid Fuel Appliance Installation Technician certified by the New Zealand Home Heating Association.
  • Install a heat transfer kit - most wood burners generate more heat than you need for one room. Unless your house is open-plan or has internal door openings that go right up to the ceiling, excess heat won’t easily get to other rooms. Heat transfer kits distribute the heat by pumping the warm air into other rooms in your house. You can buy these kits from DIY and electrical stores, but we recommend you contact a professional tradesperson for advice as there are a lot of factors that can affect how well they work.

Local council website directory - LGNZ website

List of authorised wood burners - Ministry for the Environment website

New Zealand Home Heating Association website

Using wood burners wisely

Burning dry, untreated wood of the right size and operating the wood burner correctly helps avoid air pollution that causes premature death, hospitalisation and respiratory illness.

  • Follow the manufacturer's operation and safety instructions.
  • Use safety guards to protect children and pets.
  • Plan ahead and use well-seasoned, dry firewood - stored under cover in a well-ventilated, windy and sunny place for at least a year to dry out before use.
  • Burn firewood of the right size – less than 110mm diameter.
  • Use the right wood at the right time - lighter wood (often called 'softwood') like pine is good for making kindling and getting a fire started. Once the fire is well established, denser wood (hardwood) will burn for longer and give more heat. If you can, use wood from plantation forests (for example pine and gum) rather than native woods like manuka.
  • Don’t burn chemically treated wood or salt impregnated wood like driftwood -they can corrode your wood burner and flue, emit toxic gases and leave toxic residues in the ash and flue.
  • Don’t burn coal in a wood burner, unless the manufacturer specifically says you can - otherwise you can damage your wood burner.
  • Regulate the heat output by adjusting the amount of fuel you load - don’t dampen the air control.
  • Keep the air setting high enough for a clean burn - too much or too little air cools the fire, and produces smoke. Place large pieces of wood on a good bed of embers and set the burner at a high temperature.

Learn how to light a fire cleanly and efficiently by watching this helpful video of the New Zealand Home Heating Association:

Learn how to burn smoke free - NZHHA website

Maintaining your wood burner

Maintaining your wood burner regularly is important for safety, performance and longevity. If a poorly maintained wood-burner causes a fire, it may also invalidate your insurance cover. Most wood burners and flue systems have parts that you need to replace or clean periodically. Don’t burn coal in a wood burner or you’ll damage it. Ask the manufacturer to recommend someone to inspect and service your wood burner, or contact a member of the New Zealand Home Heating Association.

New Zealand Home Heating Association website

Open fires and older wood burners

Open fires are often inefficient - most of the heat is lost up the chimney. They also create a draught that draws cold air into the house and produce large amounts of air pollution. Older wood burners and pot belly stoves are also inefficient and produce air pollution.

What to do with unused open fires

If you have an open fire that you don't use, stop draughts by putting some crumpled up newspapers into a plastic shopping bag to block up the chimney. If you do block the chimney, make it very obvious so nobody tries to light a fire with the chimney blocked.
You can also replace an open fire with a modern enclosed wood burner which will perform much better.  Insert models can often be fitted into an open fire space.