Pellet burners

Most pellet burners look like a conventional woodburner and are available as either a free-standing model or an insert into a fireplace. You can also get a basement furnace model for central heating.

Pellet burners burn only compressed wood pellets, which you buy in 15kg or 20kg plastic bags or in bulk. The pellets are loaded into a hopper at the back of the unit and are fed into the fire through an automatic feed system.

Adjusting the rate at which the pellets are consumed lets you control the amount of heat produced.

In some models, a thermostat can be used to keep an even room temperature – and a timer can automatically switch the burner on and off.

In freestanding and fireplace-insert models, a hopper load of pellets lasts for around 24 hours of continuous burning – and these models produce a similar amount of heat to a conventional woodburner. Basement furnace models produce much more heat.

There can be big variations in the price of pellets, so shop around for the cheapest source. If there's a pellet mill close to you, try there first.

To get a good price, consider buying a year’s worth of pellets.

In the past few years, pellet burners have enjoyed a reasonable uptake, but the market remains small compared to other heating options. The limited number of wood pellet suppliers (often only one per town or city) means that if a supplier in your area closes shop, pellets could become prohibitively expensive. Check there is a manufacturer near you before investing in a wood pellet burner.

We recommend you ensure there is a well-established pellet supplier near you before investing in a pellet burner. If you have access to cheap firewood, it’s probably best to go with a woodburner.

• Freestanding, insert or furnace: Fireplace-insert pellet burners produce as much heat and are as efficient as freestanding models, making them a good option if you’re short on room space or have an existing fireplace alcove to fill. Furnace models are designed to be located in the basement or other close off space. From there, they can be connected to water-filled radiators, under-floor heating or (via a heat exchanger) standard central-heating air ducts, to distribute their heat throughout the house.
• Heat output: The maximum output of most pellet burners designed to be installed in a living room is between 9 and 11 kW. But overheating the room is less likely with a pellet burner, because the heat output can be controlled over quite a wide range – usually 1.9 to 11 kW.
• Wetbacks: Some models can be installed with a wetback (water heater). This can reduce your hot-water bill (but possibly not enough to recoup the wetback's expensive installation costs).
• Cleaning: Pellet burners produce less ash than conventional woodburners. Once a week is usually enough for emptying the ash tray and cleaning out the burner. Most models have a pull-out ash tray.
• Controls: Pellet-burner controls – the on/off switch, start button and heat-control knob – are all electrical.
• Flue system: Flues are typically 75mm in diameter (smaller than conventional woodburners’). Flue arrangements can be varied: fireplace-insert models can have their flue inside an existing chimney; freestanding models often have their flue exiting the room horizontally through an exterior wall and then running up the outside of the house.
• Thermostat: Pellet burners fitted with a thermostat allow the room temperature to be automatically maintained a set level.
• Timer: Allows the burner to be automatically started and stopped at pre-set times.
• Safety guards: The surfaces of a pellet burner can get very hot and be a danger to small children. Protective guards are available and highly recommended.

Installation

• Installation costs: Every house is slightly different, but installation costs should be similar to those for a woodburner. Remember there needs to be a power outlet nearby.
• Building consents: A building consent is required to install any solid-fuel space heater (woodburners, pellet burners and diesel burners). The requirements vary between regions – check with your local council to find the requirements in your area. Some regions have more stringent regulations due to recurring air pollution issues, especially Nelson and Christchurch where low-emission burners are mandatory.

Disposing of ash can be a messy job, but it can also be a dangerous one if not done correctly.

• Don’t use a plastic or wooden scoop or bucket. Only use metal ones.
• Make sure there are no live coals in the ash – preferably empty the burner well after the fire went out.
• Don’t place the ash in a rubbish bin until it’s had a few days to cool down outside and shows no sign of igniting.
• Store any ash well away from structures, such as your house, to avoid accidental damage if it does ignite.
• Use ash to fertilise your lemon tree or roses or add it to your compost. Make sure it’s cool first.

If someone in your home has a respiratory illness such as asthma or COPD (chronic obstructive pulmonary disease) then see our article Burners and respiratory illness for what to look for when buying a new burner and how you can reduce pollution in your home.