Modern Wood Appliances- Just the Facts

Washington State is timber country and at Custom Hearth, Fireplaces and Stoves, we are constantly updating our education on wood heating appliances, making sure to carry the most efficient wood appliances on the market, and familiarizing ourselves with new wood burning technology. We’ve discussed unit and chimney maintenance, let’s talk about how the appliances work.

Wood Stoves and Emissions

The process is simple right? Light some wood on fire and you get heat, what could be hard about that? Turns out, there is quite a bit of science behind that oversimplified explanation which also leaves out the most important part- the appliance you’re burning in.

How does fire work?

We all know the basic Combustion Cycle:

FUEL + AIR + HEAT = FIRE

But what you might not know is that depending on which stove you use to create this process, the BTU output, quality of fire and even the amount of useable energy burned is affected. Thanks to EPA standards, all woodstoves sold in the US must meet emission standards of less than 2 grams per hour. Thankfully, Washington has always been ahead of the curve and our state minimum has been 4.5 grams per hour since 1998 for non-catalytic appliances, so meeting the 2-gram standard was not a big change for us. There is talk that the EPA will lower the emission rate even further by 2020 to mandate that all solid-fuel burning stoves sold emit less than 1 gram per hour.

What are emissions?

The dictionary term for emissions are “the production and discharge of something”. In the hearth industry, we are referring specifically to solid fuel fires and smoke. Emissions from solid-fuel burning appliances can be quite concerning. As defined by the EPA: Smoke from residential wood heaters contains fine particle pollution, also known as fine particulate matter or PM2.5, along with other pollutants including carbon monoxide, volatile organic compounds (VOCs), black carbon, and air toxics, such as benzene. It’s these particles that EPA certified solid-fuel burning appliances are required to cut down on. This is accomplished using one of two types of combustion: catalytic and non-catalytic. Woodheat.org has a great explanation of the differences between these two systems here.

How do emission standards and clean burning appliances affect me?

The short answer is: savings. Whether you have a catalytic or a non-catalytic combustion system in your wood stove, you will be looking at a noticeable decrease in fuel consumption. This means less cords of wood each winter, less splitting and stacking, less loading the stove, less cleaning, less creosote, less everything! Everything, that is, except heat.

I’ve heard that catalytic combustor stoves are no good, is that true?

Each combustion system has its pros and cons, just like literally everything else in the world. Some pros of a cat stove are that it produces a low and slow even burn, much less emissions and virtually no smoke or creosote (if properly maintained and the wood burned is sufficiently dry).

Chances are, if you’ve heard that catalytic stoves are useless, you (or the person you were talking to) was around in the 80’s when wood stoves first started getting tested for emissions in Oregon. At this time, most manufacturers’ stoves were not passing this test. They added a catalytic combustor, and now they did! However, these stoves weren’t designed to have a catalytic combustor in them, the cat was added after the unit was designed and this led to much heartache and headaches throughout the industry.  It was only after the EPA passed its 1988 New Source Performance Standards that proper testing methods were introduced and stoves began to be designed around the type of combustion system the manufacturer was going to use.

These days, the catalytic combustor is integrated in to the design and as long as the unit is maintained, not over-fired and dry wood used, there should be no issue with its performance as it provides slow and even heat.

Are air tubes necessary in my wood appliance?

Absolutely. If your appliance does not have a catalytic combustor, chances are it has a secondary burn system consisting of air tubes and baffles, designed to move heated air throughout the firebox and “re-burn”, if you will, all of the particulates first released by the initial combustion of the fuel. The air tubes vary in size, length, width, even the air holes and the gauge of steel used can vary from stove to stove. Remember, your stove was designed and built around this entire system, putting random air tubes, (or, God forbid, no air tubes!) can result in incomplete burns, increased emissions and dirty glass as there is not enough hot air washing over the glass to keep it clean.

What about ‘hybrids’?

Some manufacturers have taken the best of both the catalytic and non-catalytic systems and Frankensteined them together to create a fire producing monster known as the hybrid. This system is exceptionally efficient, most producing less than 1 gram of emissions per hour, boasting 10+ hours of burn time on a single log, all while keeping the glass incredibly clean. These stoves are expensive, no doubt, and require care and patience when starting a fire, which needs to be nice and hot to burn effectively. The result is gorgeous, almost mystical looking, rolling flames that are unparalleled by other stoves. Next time you stop in our showroom, ask us to light a fire in one for you; we guarantee you’ll be blown away!

Zero Clearance and Masonry Wood Fireplaces

Zero Clearance (ZC) is a term used in the industry to describe appliances that are built-in to the construction of the building. These are usually metal “boxes” with metal chimney pipe extending up to the roof. More often than not, there will be a wooden chase built around the fireplace to hide the pipe and make it look more like a traditional fireplace with a masonry chimney.

Some manufacturers make ZC fireplaces that are efficient heaters; they have doors with gaskets that latch tightly, they will have a secondary burn system, usually a catalytic combustor, and even an option to use the fireplace as a central heating system.

Other manufacturers are still making zero clearance can fireplaces. These types of appliances, as well as masonry (brick) fireplaces and chimneys are basically like having a giant hole in the side of your house. They produce little to no heat and suck the warm air from the rest of the house and shoot it straight up the chimney.

Energy.gov has a great article about different types of wood appliances and we do like how they sum up masonry fireplaces: Designed more for show, traditional open masonry fireplaces should not be considered heating devices. Traditional fireplaces draw in as much as 300 cubic feet per minute of heated room air for combustion, then send it straight up the chimney. Fireplaces also produce significant air pollution. Although some fireplace designs seek to address these issues with dedicated air supplies, glass doors, and heat recovery systems, most traditional fireplaces are still energy losers. When burning a fire, you should turn your heat down or off and open a window near the fireplace.

Custom Hearth, Fireplaces and Stoves is committed to representing the best in the wood appliance business and we have had long-standing relationships with top manufacturers for many, many years. We are passionate about wood heat and are happy to answer any questions you may have about getting a wood burning appliance installed in your home, give us a call today, 360-373-1332 for Port Orchard or 360-779-1331 for Poulsbo.

Stay warm!