Absolute Steel Hybrid: Clearances

After a fairly long wait, we finally have the official report on the Absolute Steel Hybrid clearances from the independent UL Safety and Clearance testing.

Hybrid Clarifications

After our last hybrid email and blog post, we received requests for additional clarification about hybrid combustion. What is the difference between a hybrid stove and a stove with a catalytic combustor or secondary combustion?

Q&A about Hybrid Stoves

As a factory direct company, we get calls everyday with customers asking questions about our hybrid technology. If you are curious about hybrid technology but have not called, please read our Q&A addressing some of the most commonly asked questions, and be sure to comment below if you have a question that we have not addressed here.

Q . What is the biggest difference between the new hybrid stoves and the more traditional wood stoves made at the Woodstock Soapstone Company (the Fireview, Keystone and Palladian)?

Durafoil Steel Catalyst

A. The biggest difference is that hybrid technology allows us to achieve ultra-low emissions.  We developed hybrid stoves as part of a quest to achieve lower wood stove emissions. The traditional stoves (Fireview, Keystone and Palladian), are similar to a reliable, fuel-efficient, family sedan (think Honda Civic). The smaller fireboxes and stainless steel Durafoil catalysts allow our catalytic soapstone stoves to burn cleanly and have great low emissions performance.  The hybrids have bigger fireboxes and spectacular emissions performance at all outputs.

Nine years ago (in 2007) we started to research ways to make our stoves burn cleaner.  We knew that new EPA regulations were coming.  Our 2007 wood stoves (Fireview, Keystone, and Palladian) already met what are now the 2020 emissions standards, but we made them even better.  We improved the longevity and performance of the catalysts in these stoves by making them out of Durafoil.

But until we introduced the Progress Hybrid Stove in 2011, all wood stoves used either a catalytic combustor or a secondary combustion system to meet EPA emission standards.  By combining the two (catalytic combustor and secondary system) we were able to achieve efficient, low-emission burns throughout the entire burn range (low-medium-high) that were dramatic, consistent and predictable.

Q . What is the difference between catalytic combustion and secondary combustion? Is one better than the other, or better together?

A.The difference really comes down to the temperature needed for each system (catalytic system and secondary air system) to begin to clean up emissions.  A stainless steel catalytic combustor heats up very quickly and depending on conditions (wood, draft, operator) it can be engaged within minutes of loading the stove, or as soon as the internal temperature is around 400°. Catalytic stoves burn best at low to moderate burn rates, which tends to be the most common way to operate a wood stove for overnight and daytime burns while at work. Catalytic only stoves test with lower emissions and greater efficiency than their secondary air system counterparts, and do require periodic cleaning of the catalyst to work most effectively.

The secondary air system requires higher temperatures (between 1000-1100° internally) to start burning the combustible gases in the wood smoke. Most secondary air only stoves burn best at moderate to moderately high burn rates, when the internal temperature is at its peak. Due to the high temperature requirement, secondary air only stoves have a higher tested emissions level and a lower efficiency than catalytic style stoves.

If you combine these two separate means of lowering emissions and increasing efficiency, you have what we would consider the “Gold Standard”, a hybrid stove that will burn cleanly throughout all the variations in burn rates and customer operation.  Hybrid technology is uniquely effective at high burn rates where either system may struggle alone.  The hybrid design is also very effective with large firebox stoves, which can produce a large volume of combustible gas and particulates.

Cutaway view of the Progress Hybrid

Q . Are there differences, other than emissions, between the hybrid woodstoves and your traditional woodstoves?

One example of custom art for the Ideal Steel Hybrid

A.  Yes.  As part of the hybrid development process, we have developed ways to make our new hybrid stoves more efficient, more affordable, and customizable.  These are all “extra” benefits from doing extended R&D over the last nine years.

Focusing on combustion design to reduce emissions also helped us to make our stoves more efficient.  We discovered that we could make high performance stoves that were completely affordable if they were fabricated from steel rather than cast iron.  Then we realized that we could customize stoves made of steel, which would have been prohibitively expensive with cast iron. Plus, making stoves out of steel has the added benefit of being fully fabricated in our NH factory, which ties back into greater affordability and the ability to customize.

Q . Why are you promoting only the Hybrids during this sale?

A. Partly it’s to focus attention on the Absolute Steel Hybrid, which we are introducing during this promotion.  We’ve made a big commitment of time, energy, and resources to cleaning up wood burning technology, so of course we want to talk about it and of course, we want to keep improving our combustion designs.

Outdoor Air Quality vs Indoor Air Quality. What is the difference?

The short answer is that there is no difference.  Outdoor Air becomes Indoor Air.  Most of us spend more time indoors than out, so the quality of Indoor Air is just as important as Outdoor Air.  Perhaps even more.

A lot of people don’t give much thought to Outdoor Air Quality.  We at Woodstock Soapstone think about it all of the time.  We have to.  It’s part of our business.  But we also think about Indoor Air Quality.  Many people use Indoor Air to satisfy the combustion air for their wood stoves.  In very tightly sealed houses, the amount of Indoor Air available for a wood stove may be limited or reduced by the tightness of the house (super insulated) or by negative house pressure.

Some houses are so tight that turning on the kitchen exhaust fan can compromise performance of the wood stove.  In other cases, wood stove performance can be enhanced by cracking a window.  In both cases, house tightness/negative pressure affects stove performance. This is why every stove we build has the option of an outside air adapter, and our new Absolute Steel Hybrid has an Outside Air Adapter built-in.

More and more people have been installing outside air adapters on their stoves.  Some States and local jurisdictions now require it.  All mobile homes require a wood stove to have an outside air adapter installed. Check your local laws if you are in doubt.

The outside air adapter on our new Absolute Steel stove is unique in the wood stove industry for two reasons:  1) All of the air that goes into the stove (primary, secondary, and catalyst air) has to go through this one opening, and 2) it is virtually leak proof.  If you really want to protect the air to your stove from other air circulation in your house, and more importantly the negative pressure in a tight house, this is the best way to do it.

Click to Enlarge 

Our wood stoves are not only clean burning, our new Absolute Steel stove is one of the best stoves ever made at maintaining clean inside air as well as clean outside air.  We feel the Absolute Steel has the finest outside air adapter design in the industry.

And, to make life easier for you, we build an outside air adapter into each Absolute Steel stove we make.  If you don’t need it now, you may need it later, and it will be there for you.

R2Z Detour: Introducing Our First Test Stove

As we noted in an earlier post, we are taking a slight detour in our Race to Zero.  We are testing older stoves made in the 1970s and 1980s.  Stoves which were made with little technology to reduce emissions or improve efficiency.

Huntsman Stove - Before the Makeover

Our first test stove is a “Huntsman” (made by Atlanta Stove Works, circa 1977) step stove.  It is a welded steel stove, with a huge firebox (well over 5 cubic feet), and cast iron doors with six draft controls.  The bottom is lined with firebrick, and the side walls are also lined up to 9” in height (one layer of firebrick).  As with many steel stoves of this vintage, the stove itself is almost “overbuilt” (1/4” and 5/16” boiler plate), and as long as the firebricks are replaced periodically, it will last for a few more decades.  

Huntsman Stove - After the makeover

Interestingly, even though the Huntsman stove is physically huge, it weighs almost exactly the same as our new Absolute Steel Hybrid - just over 500 pounds.

Our first goal is to establish a careful baseline profile for these older stoves in terms of heat output, emissions, and efficiency at low, medium, and high burn rates.

Next, we want to see if we can design a retrofit catalyst and heat exchanger that will improve the performance metrics (heat output, emissions, and efficiency) enough to make them competitive with some of the stoves in today’s market.

We have wired the Huntsman in our research department so that we can measure surface and gas (O2, CO2, and CO) temperatures  at multiple locations.  The stove is on a scale, which allows us to measure the rate of fuel consumption.  Finally, we can (and will) get particulate catches for most of the baseline runs using Method 5G3 (the same Method the EPA uses).  We will use the Canadian CSA B415 algorithm for calculating efficiency.  We are trying to run parallel to the same methods and standards used by the EPA.

We are using cordwood for our testing because it is readily available, and is much less expensive than the cribs the EPA has used for emissions testing during the last few decades.

We’re doing our best to keep loads representative in terms of species, weight, and moisture content.  One of the nice things about R&D testing is that we can operate with a certain degree of informality that you can’t do with certification testing.  We are just interested in seeing if we can “move the needle” before we pay attention to all of the fine points of test protocol.

We hope to get baseline data on at least three stoves (one small; one medium; and one large), and we hope to develop mathematical models for different aspects of our testing – an example would be the heat transfer achieved by our device.  More on that in the next week or so.

Obviously, there is an opportunity to reduce emissions in old stoves.  We think there are additional opportunities to extract more heat (both by radiation and convection) around the area where our device would be installed.  Without getting too esoteric, we may be able to point the catalyst directly at the surface(s) we want to use as primary radiators.  Finally, the catalyst should introduce a considerable pressure drop into the system.  This resistance may result in increased stack temperatures around our device, a reduction in stack flow, a lowering of the burn rate, and some improvement in efficiency.  Well - we are hoping to get these results!

The questions are: (1) How much of a reduction in emissions?  (2) How much additional heat extraction?  (3) How much of an improvement in efficiency?  (4) At what cost and what degree of difficulty?

We expect to be busy in the lab with this project for 3 to 4 months, at least. We don’t know if we can succeed with this R2Z Detour, but we think it’s worth making a serious effort.

R2Z Detour: Once There was a Thought...

In the beginning, there was a thought, and that thought grew into an idea, which became a project. And that was good.  We here at Woodstock Soapstone are always creating, tinkering and thinking outside the firebox. 

There are a lot of old woodstoves still in service that predate EPA regulations.   These are hefty stoves, made of cast iron or welded from plate steel and lined with firebrick.  Many are well over 30 years old, and might last another 30 years if the firebricks are periodically replaced and appropriate parts and gaskets maintained.  

Warner Stove

In our race to zero emissions, we thought we would take a side trip, a detour if you like, and look at a situation that is painful to us.  How can we get these old pre-EPA-regulation stoves that are still being used, to burn with more heat and lower emissions? These old stoves are not efficient, or clean burning.  

Warner Stove

Other people have (obviously) thought about this problem. In fact, in 2014, the Puget Sound Clean Air Agency had a retrofit design challenge to encourage development of retrofit pollution reduction devices for woodstoves.

Retrofit stove pipe catalysts have been available since the early 80's, but the concept has never been fully developed.  One of the simplest catalytic retrofits is a catalytic damper that pivots in and out of the exhaust stream (below) in an effort to reduce emissions.

Catalytic Retrofit

Similarly, others have tried to extract more heat from the stovepipe by inserting a heat exchanger downstream of the flue collar.  Some heat exchangers merely relied on convection, while others used a fan.   

Heat Exchanger

 We are in the very early stages of developing a retrofit stovepipe device that would increase efficiency and produce a cleaner burn in older wood stoves. We are eager to use today’s technology and improved materials to create a device that both increases heat output and reduces emissions.

We are in the early stages of getting baseline data for how some of these older stoves actually perform.  We have already started to fiddle around in the lab and some of the early signs are encouraging, though there are some difficult hurdles we will have to get over before we can even think about a commercially viable retrofit solution.

Consistent with our other recent projects, our goal will be a device that is simple, effective, and affordable.

We are considering making the data and development of this project publicly accessible.  Many of our customers are engineers, and we can use all of the thoughtful input we can get.   Again, we are very early in the project, but stayed tuned for the next chapter in this newest adventure here at Woodstock Soapstone.

A Visit to the Factory

A recent visitor to our factory graced our facebook page with a beautiful collage of pictures taken during a tour.  You can view the page here. We are thrilled our visitors shared their pictures.  We thought we would take a moment to share them with you, and hope you enjoy them as much as we do.

If you are in the area, we invite you to stop in and visit our showroom, explore the stoves we have on display, and take a tour of our factory.  Our showroom/factory hours are 9:00 to 5:00, Monday thru Saturday.  No appointment is needed.  Our fabricators, welders, and other employees are busy in the factory until 3:30, Monday thru Friday, but they do not mind a visit from you. 

Ideal Steel Hybrid with Maple Leaf Design

When you first enter our factory area, you may come across an Ideal Steel Hybrid stove (or two, three or more) that are in the inspection phase.  Before your stove is shipped, it gets thoroughly inspected to make sure everything is working as it should.  This particular stove has the maple leaf design (NAT006) on it. 

Front of Ideal Steel Hybrid

Looks like these folks are getting a close up view of the front of the Ideal Steel and the ash pan.

Absolute Steel in Black with Metallic Mahogany, Prairie Wheat Pattern

Sitting near the Ideal Steel Stoves, waiting for inspection, is our newest stove, the Absolute Steel Hybrid.  This one is black, and has the Prairie Wheat pattern in Metallic Mahogany.  We have been building Absolute Steel beta stoves for test purposes.  We should have comments and results regarding UL clearance and other information for our new Absolute Steel Stoves posted soon.

Ideal Steel Andirons

As you walk towards the rear of our factory, you will go through the area where our Fireview, Keystone and Palladian stoves are made.   This picture shows some of our Ideal Steel Andirons which are lined up, waiting to be installed into a stove or shipped to a customer.

Fireview ready for shipment

Moving along through the Fireview section, we find a Fireview stove which is complete, waiting to be crated for shipment.

Section of our Factory

Section of our Factory

For over 38 years we have been building stoves and warming homes. From cast iron, soapstone, tubular steel, flat sheets of metal, designer art work, with fewer emissions and greater fuel efficiency, our engineers and employees never stop creating and designing.  We all work hard to bring the best product we can to our customers.

We enjoy having folks come to our showroom, and to see first hand what we do and how we do it. We are open 9-5 Monday thru Saturday.  You may have a factory tour any time we are open, with no special arrangements needed ahead of time.  Keep in mind that the shop is active until 3:30 in the afternoon, Monday thru Friday.  We hope to see you soon!

Baby It’s Cold Outside! Optimize Your Wood Stove Experience

The temperatures have dropped and it is freezing outside!  At least it is where we are.  This is when it is especially important to optimize your wood stove, to get maximum heat and enjoyment for minimal wood usage.

To really get the utmost benefits from your Woodstock Soapstone Stove, it is important to make sure the following maintenance and precautions have been done: 

• The pipe needs to be clean.
• Chimney cap (if you have one) needs to be free from obstruction.
• Combustor needs to be clean.  Vacuum all sides.  If you have a stainless steel combustor, you can spray the combustor with a solution of 50% distilled water and 50% white vinegar.  Let it drain, then rinse well with clear distilled water and let dry completely before putting the combustor back into your stove.  Using the vinegar solution may help to clean baked on fly ash.  You can learn more about cleaning your Progress Hybrid combustor here, the Fireview combustor cleaning information is here, and the instructions for cleaning your combustor if you have a Keystone or Palladian stove is here.
• The ash pan should be clean, and the bottom of the stove should not have too much ash.  
• Wood should be dry.  For the best heat output from your stove, wood should be well seasoned. Most wood will take one to two years split and stacked, and covered on the top (tarp or other protection) to dry properly.  If your wood is not dry, you will find much of the heat your stove is generating will be absorbed by burning off the moisture in your wood.  If your wood is not as dry as you would like, mix it with kiln dried, or with compressed wood chip logs (available at most hardware stores, lumber yards or home/garden centers in the heating season), or you may need to leave your air setting open a bit more for more heat in the firebox.   
• Check your gaskets (when the stove is not hot).  If you think your stove is getting too hot, check your gaskets for leaks.  This is a primary cause for your stove to overfire.  The paper test is an easy test to check the door gaskets.  Simply take a strip of regular paper, put it into the side of the door.  Close the door.  If you can easily slide the paper out, you need new door gaskets, or perhaps you need to adjust the door latch.

Progress Hybrid

Now that your stove is in prime condition, and your wood is in good condition, it is time to sit back and enjoy the dancing flame show that only a Woodstock Soapstone Stove can give.

Pour your favorite beverage, or perhaps put a pot of cider on the top of your stove (a little cinnamon never hurts) and you can enjoy a tasty beverage and wonderful smells while you watch your light show.

What's Cooking?

When there is a major storm in the forecast, it means many of us may loose our electricity.  This is when it is very, very nice to have a Woodstock Soapstone Stove.  Water can be heated on a wood stove, but I can also cook dinner on my wood stove.  This is a wonderful thing, especially when the power is out.

We have heard from some of our amazing customers about how fabulous it is to be able to create meals on their Woodstock Soapstone Stoves, and we thought we would share two of our recipes and a few quotes from our customers. 

Keep in mind there may be times it will be necessary to elevate your Dutch oven to protect the contents from becoming too hot, or to allow the contents to cook evenly, such as when baking/cooking bread.  A metal or cast iron trivet works well for this, just make sure you do not have rubber or plastic feet on anything you place on top of a hot wood stove.

Starting with soup; we have a recipe for Homemade Vegetable Soup.

Homemade Vegetable Soup

Homemade 
Vegetable Soup

• Vegetables (turnips, squash, zucchini, tomatoes, mushrooms, onion, beans, peas, corn, etc.), cut into pieces or chunks
• 2 stalks celery
• 6 or more baby carrots, cut into chunks or pieces
• 1 large onion, cut into small pieces
• 1 small can whole kernel corn (fresh is even better)
• 3 medium potatoes, cut into small pieces
• 5 cups water
• Meat, (beef, chicken or pork – optional)
• 1⁄2 teaspoon Worcestershire sauce
• 4 teaspoons or 4 cubes vegetable bouillon
• 1 teaspoon salt
• 1 teaspoon pepper
• 1 can stewed or diced tomatoes with juice
• Leftover rice, noodles, broccoli or whatever’s in the fridge 

Place all of the vegetables in large pot and add the bouillon and water. If adding meat, cooked is better, but if it is raw, brown in butter first, then add to pot.

Add remaining ingredients, and simmer for at least 3 hours.  We usually cook our soups 4 to 5 hours. Check liquid level every now and then.  Otherwise, let it simmer.  I usually put it toward the back of the wood stove as well, where it’s hotter.  If it seems to be getting too hot, move it to the front.

Serve with fresh bread for an unbelievably good meal and just the right thing for a cold winter night. Yields 3 to 4 servings.

Now for the bread.  To bake bread on the top of a wood stove, you need to heat up a cast iron or heavy metal dutch oven.  One that has a tightly sealing lid.  You need to keep the heat and the moisture in the container with the dough.  Grease your cooking pot with some Crisco or butter and get it nice and hot, about 15 minutes on the top of a hot stove.  I like to make Beer Bread.  This is a very dense, hearty type of bread.  The Beer provides the yeast and the ingredient list is short.  If you’re using self-rising flour, you only need three ingredients.  If you’re using flour that is not self-rising, simply add one teaspoon of salt and 3 teaspoons of baking powder.  I recommend using a beer that has not been overly pasteurized, too much pasteurization of the beer kills the yeast

Beer Bread

• 1 (12 fluid ounce) can or bottle beer
• 3 cups self-rising flour
• 3 tablespoons white sugar
If you're using regular flour - add one teaspoon of salt and 3 teaspoons of baking powder to the flower before adding the beer and sugar to the flour.

In a large bowl, mix together the sugar and flour.  Add beer and continue to mix. Batter will be sticky. When all of the ingredients are throughly combined, put into a 9 x 5 inch greased loaf pan.

Bake at 350 degrees F (use your on-the-stove thermometer) for 50 for 60 minutes.  The top will be crunchy, and the insides will be soft. Serve topped with butter or cheese spread.

We hope you enjoy these two recipes for cooking on your wood stove.   We would love to hear about your experiences with your Woodstock Soapstone Wood Stoves.  Check out our facebook page here.  We invite you to post your pictures, and your stories of how you survive without power. 

Here are a few comments we have received about cooking on your Woodstock Soapstone Stove:

“…During the ice storm of this year- my Keystone kept the house quite warm- and…kept our bellies full! I made stove- top pizzas right on the Keystone! Everything was defrosting in my freezer- so out came the dough and a few essentials- onto the stove for 20 minutes and voila pizza for everyone!...” Wilmot, NH

“… we were without power for 12 days. While our neighbors ate cold meals and survived freezing temps, (and pipes), ….we stayed reasonably warm and enjoyed pot roast, beef stew, baked potatoes and hot soups thanks to our Fireview.” Jaffrey, NH

If you want to read more about cooking on our stoves, click here.

Oops! We Stand Corrected!

A welcome correction (0.5 g/hr emissions!) is more good news.

We initially reported a weighted average emission (the number the EPA reports) of 0.7 g/hr.  An error was made.  Our weighted average emission is actually 0.5 g/hr.

This is, of course, very good news!  Results of individual runs and weighted averages are in the chart below.