What Do Efficiency Ratings Mean, Anyway?

Whether you’re comparing wood, gas, or pellet-fuel appliances, you’ll see an efficiency rating listed in the product information. Between uncertain fuel costs and increasingly strict air quality regulations, more and more consumers are looking for the most efficient heaters they can find. But what do those ratings mean? How are they measured?

The bad news is that there isn’t one standard rating system used by manufacturers, nor are they required to tell you which system they’re using. The good news is that by learning a bit about what the ratings mean, you can put manufacturer claims in context and compare apples to apples when buying a stove or fireplace.

What does “efficiency” actually mean?

In the simplest terms, the efficiency rating on an appliance tells you how much of your fuel will become usable heat in your home. A pound of wood, gas, or pellets contains a certain amount of potential energy; some of this energy will be used in starting and sustaining combustion, some of it will go up the chimney (carrying away particulates and other undesirable byproducts of combustion), and the rest will come out into your home as heat.

Wood Heat: EPA vs. Real-World Performance

Wood stoves and inserts are sometimes advertised with two efficiency ratings: EPA and cordwood/real world performance. EPA testing procedures are focused mostly on particulate emissions, and are very highly standardized. These tests use milled lumber (often pine), precisely stacked, with the stove draft set to its lowest (and smokiest) setting; this is also referred to as a “crib wood” test. While this is useful for determining how much air pollution a stove will generate, it has very little to do with how efficiently your stove will convert firewood into usable heat in your home. Many companies choose to do their own testing with cord wood (usually hardwood) and realistic venting setups, in order to give their customers a more accurate idea of stove performance. Unfortunately, there’s no requirement that companies tell you which efficiency rating they’re listing. For environmental impact, focus on the emissions listing (gm/hr of particulates released into the atmosphere) rather than the listed efficiency rating. For real-world efficiency, a good rule of thumb is that 67%-75% is a good range for quality non-catalytic stoves, with catalytic stoves occupying the 75%-83% range.

(Note: just to make this even more confusing, the EPA is currently in the process of revising its compliance and listing standards. While this process is ongoing, look for “cordwood/HHV/actual measured efficiency (CSA)” in your stove literature.)

Gas Heat: Steady-State vs. AFUE/EnerGuide

Gas stoves, inserts, and fireplaces are rated in two different ways. The Steady State efficiency rating, which offers a higher and more impressive number, is taken only once, after the appliance is fully heated up and burning steadily. While this number is technically accurate, it has very little to do with how your stove will perform over the course of its lifetime, and under real-world conditions. We prefer to work with vendors who list the EnerGuide, P4, or AFUE (annual fuel usage estimate) ratings. These efficiency readings reflect performance over the entire burn cycle, from ignition to cool-down, and use realistic venting setups. If you’re looking at efficiency ratings, and seeing numbers in the high 80% range, you’re probably looking at the steady-state efficiency of the fireplace. The more honest EnerGuide, P4, and AFUE rating systems give numbers ranging from around 60%-70%. A 65% efficiency rating is actually quite good, and an 85% rating, although it sounds much better, probably doesn’t reflect an actual increase in real-world efficiency or performance.

To sum up: efficiency ratings can be confusing, and don’t always give a complete picture of how an appliance will perform in your home. However, with a little bit of time and research, you can put those numbers in context when comparing different products, and make a more informed decision about which stove, fireplace, or fireplace insert will be the best fit for you!

 

Spring Inventory Reduction Clearance Sale!! Up to 80% Off!

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Big changes are afoot here at the Wooden Sun! Over the summer, we have plans to remodel our store, bring in new product lines, and expand our work into more outdoor projects! To make room for new products and displays, we’re putting all of our showroom units on sale, at discounts ranging from 10%-80% off our usual retail pricing. From April 15th-May 22nd, come into the Wooden Sun showroom for big discounts on a wide range of gas & wood stoves, fireplaces, fireplace inserts, and outdoor cookers! And be sure to look for our grilling accessories, on clearance from 10%-25% off retail price!

At the same time as we bid a fond farewell to our old inventory, we’d like to welcome the Kamado Joe line of ceramic grills and smokers to the Wooden Sun family! Every Kamado Joe cooker comes standard with cooking racks, rolling cart, grill lifter, and ash tool, so you can get started grilling right away. These grills will also be included in our sale, at 10% off retail.

No Power? No Problem!

Early 2015 brought us a lot of winter storms, and winter storms always bring at least one big power outage. Out in the country, it can be days before you get your power back, but you’ve got to stay warm in the meantime. Fortunately, Wooden Sun has your winter heating needs covered.

Valor G3Valor gas fireplaces and inserts are designed to function without a fan, and therefore without the need for electricity. In addition to the convection heating you get from all gas fireplaces and inserts, Valor has some of the best radiant heat technology in the industry. While few Valor appliances are large enough to heat your entire home, they will easily keep a few rooms warm and cozy while you wait for the power company to do its thing.

Regency Hampton H300Wooden Sun carries a variety of wood-burning stoves and inserts, to heat anywhere from 600-3000 square feet. While inserts often work best with blowers, they’ll still put out quite a bit of heat without the fan, so you don’t lose your heating capability when the power goes out (your faithful blogger has a wood insert with a very noisy blower, and she can get a great deal of heat out of the appliance without having to resort to the fan).

WiseWay pellet stoveWe’re also very excited about our most recent addition, the Wise Way brand of gravity-fed pellet stoves. While other pellet stoves rely on electric motors and augers to get the pellets from the hopper to the burn chamber, Wise Way pellet stoves have a simple gravity-feed system, which means you can still use your stove when the power goes out. Note: the zig-zag portion of the stove is actually the outlet from the burn chamber, which means that you can see the fire through the window on the side as it streaks upwards!

 

 

Common Wood Stove Problems: You Probably Don’t Need to Panic

Every season, we receive several calls from concerned stove-owners, worried that their stoves are malfunctioning and/or dangerous. The good news is that many of these problems are not actually problems at all, and merely things your stove will do from time to time. Let’s address some of the issues you may encounter in your wood stove or insert, as well as some troubleshooting steps you can take before scheduling a service call:

Discoloration

Some change in the color of your stove can be normal. If you have a stove with porcelain enamel cladding, the enamel may darken as it heats up, then return to its original color as it cools (the bordeaux enamel from Vermont Castings, for example, darkens to a particularly vibrant deep red when the stove is going).

Some wood-burning appliances have a stainless steel firebox, rather than the traditional firebrick or refractory cement. Although this lighter, thinner firebox will transmit heat to your room faster, the lighter constructions means it’s also subject to a certain amount of warping and discoloration (which looks like rust, but doesn’t damage the material of your firebox). During a chimney sweep and inspection, we will inspect any warping or discoloration in the firebox, and assess whether or not it’s severe enough to cause a problem.

Drafting Problems

Sometimes, problems with draft can cause the smoke from your wood stove to come back into the room, rather than going up the flue as it’s supposed to. While a blockage in the flue or the cap may be responsible, there are some steps you can take before scheduling a chimney cleaning.

Image courtesy of woodheat.org

Image courtesy of woodheat.org

The most frequent cause of cool, smoky fires is wet wood, so the very first thing to check is your firewood supply. Firewood that has been properly seasoned (cut, split, stacked to allow free air circulation, and left in the sun and air for at least 9 months) has a moisture content between 15-20%. Dry wood will have cracking and splitting at the ends, as shown in the picture next to this paragraph. Also, if you hit two pieces of firewood against each other, wet wood will make a dull “thud,” whereas dry wood will make a hollow, resonant “thunk.” While this isn’t as scientific or precise as a moisture meter, it will give you a reasonably good idea of how dry your firewood is. Another way to check the quality of your firewood is to look at the smoke coming out of your chimney. At the start of a good fire, the smoke coming out of the chimney will be white; after the fire is fully established, you shouldn’t see very much smoke at all, only a slight distortion from the heat radiating out of the top of the chimney, and a little bit of translucent steam.

Sometimes, the weather outside can be the problem. Damp, heavy air provides more resistance to draft, and it will be harder for your chimney to get a good draw at these times.  And a good draft requires a difference of temperature between the indoor and outdoor air, as the warm air inside your stove is drawn up the flue towards the colder air outside. If the temperature outside is above 55°F, this temperature difference will not be high enough, and it’ll be hard to get a good draft going. You can help your chimney out by pre-heating the flue (holding a burning rolled-up newspaper as near to the flue opening as you can get, for example), but some weather conditions will always interfere with wood stove performance.

Depending on where in your house your stove is installed, some problems with draft may be unavoidable. All homes have a neutral pressure plane, above which air is trying to leave the house, and below which air is trying to get into the house. Many basement fireplaces, unfortunately, are in negative pressure planes, which means they can sometimes experience backdraft from the flue connected to an upstairs appliance. There are steps we can take to reduce this backdraft, like extending one flue so that the smoke isn’t as readily pulled back into the house, but it’s an unfortunate reality that your wood stove may not perform equally well in all parts of your home.

Uncommon Stove Problems: Contact a Professional

While many stove issues are comparatively minor, there are some situations that require the immediate attention of a certified wood service professional. If the wall in front of your chimney, or surrounding the thimble where your stove plugs into the wall, becomes hot to the touch (some warmth is ok, but the wall shouldn’t be too hot to touch), or begins to discolor, stop using your stove immediately, and call your local certified stove technician. If the wall is hot or discolored (turning brown around the thimble, for example), this indicates that pyrolysis is occurring, and often that you have had (or are having) a chimney fire. We inspected just such an installation last year; the flue liner showed evidence of multiple chimney fires, and the wood studs in the wall were beginning to char around the edges. We removed the damaged parts and relined the chimney, but this could easily have started a house fire if left unresolved.

The bottom line is that your wood stove is a complex system, and it’s important to pay attention to how it’s working. If you notice something unusual, don’t panic! There will always be variations in the way each stove performs in different environments, and most of these variations aren’t cause for concern. But as always, if you’re unsure, feel free to call your friendly neighborhood Wooden Sun technicians, and we can discuss your stove problems with you.

Have a safe, warm, and happy fireplace and stove season!

 

 

Wooden Sun Summer Warehouse Sale!!

As the summer orders come in, we’ve realized that we have too many products in our warehouse, and not enough space to store them all! In order to make room for new products, we’re clearing out some of our overstock stoves and gas log sets, at prices ranging from 15-50% off! Click on the link below to see a .pdf of all of our warehouse items for sale!

All products are new and have never been used.

WS logo bullet point Wooden Sun Summer Overstock Sale

Catalytic vs Non-Catalytic Stoves: Which One’s Right for You?

So you’ve looked at your options, and are trying to decide on a wood stove. One important choice to make is whether to purchase a catalytic or non-catalytic stove. Which one is the best option for you? Each comes with advantages and disadvantages; there’s no “best” stove, only the best option for you and your home.

Whether you chose catalytic or non-catalytic, Wooden Sun wants you to make an informed choice. Catalytic stoves sometimes get a bad rap, but much of this is based on a previous generation of stoves. Early catalytic stoves were non-catalytic stoves which had been quickly adapted to meet EPA standards; the catalysts were often difficult to get to and hard to maintain, and the stoves simply weren’t as efficient as they could have been. Since then, manufacturers have vastly improved the design of catalytic stoves, and the result is a better, easier to maintain stove.

Here are the facts we have gathered together to help you make an informed choice between catalytic and non-catalytic.

Advantages of a Catalyst

If you’re looking for maximum efficiency and the cleanest burn, a catalytic stove is hard to beat. Just like the catalytic converter in your car, the catalytic combustor in a wood stove traps the smoke and other byproducts of combustion, and has a chemical coating (generally platinum and/or palladium) which interacts with the smoke and ignites it at around 500 degrees, rather than the 1100 degrees normally required. This increases the efficiency of your wood stove 5-10%, especially at low temperatures, and reduces emissions by 3-5 gm/hour. With this increased efficiency, and the ability to burn the fire very low without risk of it smoldering and producing creosote, catalytic stoves can achieve very long burn times — up to 40 hours!

Disadvantages of a Catalyst

There are a few drawbacks to a catalytic stove. The first is that the catalyst is another part that can break down, and it will eventually wear out and need to be replaced. The catalyst can also be ruined by the use of treated lumber, coal, colored or glossy paper, or other non-pure wood and fire starter sources (much as you wouldn’t put lower-grade gasoline in a high-end car). While unseasoned firewood won’t permanently damage your combustor, it will crud it up (again, like non-premium oil or gasoline in a high-end car), reducing its effectiveness. And there is an extra step in the combustion process — opening and closing the bypass damper at the correct times. A final potential drawback of a catalytic stove comes only if you have a particularly short chimney. A shorter chimney may not have the sufficiently strong draft a catalytic stove requires to function at lower temperatures, and the stove won’t be able to achieve its maximum burn time.

Advantages of a Non-catalytic Stove

So you’re concerned that a catalytic stove might require more attention than you want to give your wood stove. In short, a non-catalytic stove is simpler to operate. It doesn’t require the extra step of engaging and disengaging the bypass damper (although we still recommend monitoring the temperature to make sure you aren’t over-firing and damaging your stove). With no catalyst to damage and replace, green wood and the combustor killers mentioned above aren’t as serious a problem, although we still recommend burning only well-seasoned wood and approved fire starters at all times, and never burning trash or treated lumber. Green wood just stinks!

Non-catalytic stoves operate at their most efficient and burn the most cleanly at a moderately hot temperature. This can be an advantage in leaky old farm houses or huge spaces that need a maximum BTU output to maintain a warm environment.

Disadvantages of a Non-catalytic Stove

Although it’s easier to operate, a non-catalytic stove can’t achieve the highest levels of efficiency and the lowest levels of emissions, as compared to a catalytic. Moreover, a non-catalytic stove won’t burn as cleanly at low temperatures. And since it can’t manage the very low burn rates of a catalytic stove, a non-catalytic stove won’t be able to be able to achieve the very long burn times of its best catalytic cousins.

A Tale of Three Stoves

Blaze King Princess

The Blaze King Princess catalytic stove is among the most efficient wood stoves in the world, at 88% efficiency with only 2.42 gm/hour of emissions. On high heat, the Princess will burn for up to 10 hours; on its lowest heat setting, the stove will burn for as long as 30 hours!

 

Pacific Energy Summit

This is the Pacific Energy Summit, an exclusively non-catalytic stove. It’s 80.5% efficient, with 3.9 gm/hour of emissions, and a burn time of up to 14 hours. Simple to operate, this stove is both tough and reliable!

Vermont Castings Encore

The Vermont Castings Encore Flexburn (along with its big brother the Defiant) is unique  in that it can function as a catalytic or non-catalytic stove. Its readily-accessible combustor chamber makes it easy to examine, maintain, and replace the combustor. If you don’t engage the catalyst, this stove is 78% efficient. In catalytic mode, the efficiency jumps to 86%, with only 1.2 gm/hour of emissions.