Modern Wood Burners NZ: They Might Surprise You

According to the 2013 census, more than a third of New Zealanders were heating their homes with wood despite the lousy rap solid fuel gets these days from environmentalists. The reality is that New Zealand has extensive areas of forestry, making wood a locally available and renewable source of heat.

Trees capture carbon dioxide from the air while they are growing and release it either when the wood is burnt, or when the tree dies and rots. Therefore, burning wood sourced from sustainable forests, where new trees are planted after tree felling, within efficient modern wood burners creates less net greenhouse gas emissions compared to heating with gas, coal or electricity.

Wood burners for home heating can be particularly well-suited to Queenstown’s climate, where a Southerly blowing through could drop temperatures rapidly any time of the year, especially as a secondary heat source.

Advantages of Modern Wood Burners:

• The experience of gathering around a wood fire and the aesthetics of a flame is incomparable.  
• Many people have access to cheap or free wood such as wilding pines, which are abundant in Queenstown and considered a pest species. Modern wood burners can be relatively inexpensive to run even if you have to buy firewood.
• Wood burners work during power cuts. Many free-standing models can be used for cooking as well as heating.
• Some wood burners can be fitted with a wetback system to heat water as well for more energy efficiency and heat transfer. (See tips below)

Disadvantages of Modern Wood Burners:

• Chopping, stacking, and storing the wood is messy and labour intensive. A source of cheap, dry wood is not always available.
• Regular maintenance to remove ash, clean flues, and wipe heating surfaces of the wood burner is required.
• There’s a knack to lighting and maintaining a fire. It doesn’t provide instant heat. 
• Control over heat output rate and therefore room temperature is limited. Modern wood burners no longer bank overnight to comply with emission regulations meaning you'll need to consider ultra low emission burners.

When wood burns, it releases heat through a combination of radiant and convective heating. Radiant heating heats objects while convective heating heats the air.

The amount of each type of heat varies from model to model, and the right model for your project depends on the application. If you need to heat a large room with high ceilings or a draughty area with poor insulation, look for wood burners that produce mostly radiant heat. These will make the room feel warmer than the air temperature will indicate.

To heat smaller rooms or in a space with standard ceiling height, avoid overheating by moving some of the warm air to other parts of your home with a heat transfer kit and choose a wood burner that’s designed to create convective heat. Since convective wood burners heat the air around them and hot air rises, you’ll notice less heat in the bottom part of your room. With a convection wood burner, install a ceiling fan to help mix up the hotter and cooler layers of air, especially if you’re not using a heat transfer kit.

More Tips for Choosing a Modern Wood Burner:

• Wood burners and multi-fuel burners are prohibited in some areas, such as Shotover Country, and require a building consent to install or move in Queenstown. 
• If you’re allowed a wood burner, be sure to check the Ministry for the Environment’s list of authorised wood burners, to make sure yours is compliant with the National Environmental Air Quality Standards and clean air rules that apply in your region. 
• Freestanding wood burners tend to be more efficient and cheaper to install. However, if you have an existing open fire, an insert model can be fitted into the same space and will be much more efficient than an open fire. 
• A wetback can be cost-effective if you plan to use the wood burner daily for extended periods in winter and if your household uses a reasonable amount of hot water. Wetbacks use the heat of the wood burner to heat water by circulating water between the wood burner and the hot water cylinder through pipes. Note that some wood burners won’t meet emissions and efficiency standards with a wetback fitted so check with your supplier. You’ll also need to install your hot water cylinder reasonably close to the burner.

This was Part 2 of the Smarter Home Heating for Queenstown series. Read Part 3: Electric & Under Tile Underfloor Heating.