A report from National Radio on the effect that a warm home has for children suffering from asthma. Please copy and paste the link below into your browser:

http://www.radionz.co.nz/audio/national/ckpt/2008/05/09/efficient_home_h...

Automatic wood heating with a pellet stove

Most of us have fond memories of evenings spent near the cozy comfort of a real wood fire. These days, though, few of us have time for firewood splitting and stacking. So, if you enjoy the warmth and comfort of a wood fire, but want a more convenient option, a pellet heater might be your best bet. Pellet heaters, available as either freestanding stoves or fireplace inserts, are the automatic way to burn wood.

Wood pellets have been widely available for about ten years, making it the newest home heating fuel, but already more than 400,000 households in North America have switched. To investigate this remarkable new home heating phenomenon, let's start at the beginning.

Pellet fuel is made from the sawdust left over from lumber manufacturing. It is dried, ground up to the consistency of course flour and fed through a mill that compresses it into small cylinders 6 mm in diameter and up to 25 mm in length. The mill puts such pressure on the wood flour that the natural lignin that gave strength to the original tree is reformed to produce a shiny glazing on the surface of each pellet. In fact, pellets are much denser than natural wood. You can test this by dropping a pellet in a glass of water: it sinks!

You can't burn pellets in a regular wood stove; they would just lie there in a smoldering pile. But a pellet stove is smart. A turning auger slowly feeds pellets from a storage hopper to a small pot in the firebox that holds just a handful of fuel. A fan pulls air through the pot to produce a bright and hot, yet clean and controlled fire. The exhaust is then passed through a heat exchanger that transfers the heat into the room. A solid state circuit board controls everything: the auger speed, combustion air fan and heat circulation fan, turning them all on and off at the right times. Once properly set up, a pellet stove is a clean-burning and reliable heater. There is no visible smoke in pellet stove exhaust.

The burning of pellet fuel is such a controlled process that a regular wood stove chimney is unnecessary. Instead, a simple double-wall pellet vent is used to route the exhaust to outside. Under ideal conditions a stove can be vented horizontally through the wall like a clothes dryer, but a rise of at least five feet is usually recommended, so you need to get advice from your dealer.

The environment gains in a couple of ways when wood pellets are used for heating. First, pellets are made from sawdust that would otherwise end up as waste in a landfill where it would decompose and emit carbon dioxide and methane, the two most important greenhouse gases. Rising amounts of the greenhouse gases create the problem of global warming and may also be responsible for the climate changes that have produced extreme weather events in recent years. Although carbon dioxide is also a byproduct of pellet burning, at least homes are heated in the process instead of just letting the sawdust rot in a landfill.

The second environmental benefit is that home heating with pellets almost always displaces the use of fossil fuels like oil and gas. Burning fossil fuels increases greenhouse gases because the million-year-old carbon they are made of is converted to carbon dioxide and sent on a one-way trip into the atmosphere. In contrast, the carbon dioxide from wood pellet combustion is re-absorbed by young trees as they grow, so it is a renewable cycle.

Why is pellet heating such an appealing option? For one thing the 20 kilogram bags of pellets are convenient to use and compact to store. Also, a pellet appliance can run unattended for up to 24 hours on a hopper load of fuel, which is a big advantage for working families. Perhaps a less obvious reward is the knowledge that you are using a renewable fuel that will not contribute to the global warming problem, one that is also a recycled waste product from lumber operations that might otherwise end up in a land fill site.

When you heat your house with a pellet stove, you can feel good about it in more ways than one.

Pellet fuel is included in the Winter Energy Concession program

The front page of NZ Herald of July 13, 2007 cites a four-year study which found that air pollution claims nearly 1100 lives in New Zealand each year, with one in 20 people dying earlier than they would have. The study, conducted by more than 20 leading science and health experts in New Zealand and Australia, cites open fireplaces in homes and dirty fumes from vehicle exhausts and factories for the toll. And according to Crown Research Institute Scion, if all the houses in Rotorua, cited in the NZ Herald report as having very little chance of meeting Ministry of Environment standards, switched to using pellet fires, the levels of particulate emission would be reduced by 92%!

Parkwood fires have emission levels which are up to 50 times less than those of traditional wood burners, and can therefore reduce the risks associated with health problems related to pollution.