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Tuesday, April 19, 2016

Recent Posts

  •  Top Down Fire

            It's A Fire Sale! (of the Finest Kind)


            You asked, and we listened.  It’s been a while since we’ve featured our “catalytic stars” with a sale this big!  This occasion has come about because we have a substantial hybrid woodstove backorder, and we need to reorganize and expand our steel fabrication operations.  Turning finished inventory into funds, manufacturing space, and capital equipment is the order of the day!  Inventory of these three soapstone models is very limited.  Call today to inquire about available colors, 1-800-866-4344.

            Click to Enlarge

            Tuesday, April 12, 2016

            How to build a shoulder-season fire in a cold stove, with virtually no emissions and no effort or maintenance after you light the match! (Part 2)


            There are some very respectable technical and scientific reasons why a “top down” fire works best when staring a cold stove.  Here are a few reasons:

            First:  The distribution of oxygen to the hottest spot is better in a “top down” start-up.  Complete combustion requires adequate oxygen, and when the fire is top down, adequate oxygen is always available.  In a bottom up fire, there is likely to be less O2 at the hottest point, and there is a chance the fire can be suffocated as wood is loaded on the top of the fire.

            Second:  Less heat is lost in a “top down” start-up.  Clean combustion requires high heat. In a top down fire, as the bigger pieces at the bottom are heated up, the gasses they give off are consumed by the small hot fire at the top.  This is good combustion design!  In a bottom up fire, the gasses from the bottom pieces are cooled by coming in contact with the wood above them.

            Third:  No need to add wood or re-stoke the fire in a “top down” start-up.  Not only does this mean no work for the operator, it also means that the wood at the bottom is heated more consistently, the air-to-fuel ratio is not subjected to sudden changes, and exhaust gasses are heated, rather than cooled.   In a bottom up fire, when you add wood, the airflow is changed, the fire is cooled off (by opening the door and adding unheated wood), and more unburned gasses are created.

            Fourth:  Having hot coals at the top in a “top down” start-up is a great thing!  The radiant energy from those hot coals heats the wood beneath them.   Gasses from the wood beneath them are burned as they pass through the hot coals.  In a bottom up fire, the hot coals are at the bottom of the fuel load, so they can’t contribute to burning gasses from the wood above them.


            Four Stages of a Top Down Fire
            Click on Picture to Enlarge

            Why Woodstock Soapstone Stoves are totally clean burning almost immediately with “top down” start-up fires.

            Remember that when you build a “top down” start-up fire, you are maintaining the heat of the fire to the maximum extent.  You are not quenching the fire by opening the door, adding wood, or limiting the supply of oxygen.  There are two big reasons why we are able to clean up emissions almost immediately after light-off.

            1.  Our catalytic combustors are made of a very thin, high tech stainless steel material called Durafoil®.  The Durafoil is just 50 microns thick; about the same thickness as a human hair.  This ultra-thin material heats up very quickly, enables the catalyst to react with the exhaust gasses, and ignite very quickly.  We have been able to get our catalysts to ignite easily in five minutes or less using a “top down” fire and dry kindling. 

            2.  Our hybrid stoves supply secondary air through a flat, perforated, stainless steel fireback, and are able to achieve secondary combustion within minutes of lighting a “top down” start-up fire.   A “top down” start-up fire creates the maximum amount of start-up heat.  The kindling flames high in the firebox are more than adequate to initiate secondary combustion.

            To sum up our story, if you have a Spring Chill in your home, cool at night but warm enough during the day, try using the "top down" start-up method to start your fire.   You should find your stove will heat up faster to ward off that chill, and your fire will burn longer and cleaner.  And, you can astound your friends and family with your pyrotechnic expertise.  





            Monday, April 11, 2016

            How to build a shoulder-season fire in a cold stove, with virtually no emissions, and no effort or maintenance after you light the match! (Part 1)


            We are now in the “shoulder season”, where we have warm days and cold nights.  There’s no need to burn the stove all day – it is a waste of wood, and the house will be too warm during the day when the sun is out.

            The most efficient way to heat with wood, during this time of year, is to build a fire in the early evening and then let it go out.  Here is a simple, efficient way to build a “top down” fire that will not need tending, and will keep the house warm from late afternoon through bed-time (and through the night, if you want, just add wood before bed).

            First:  Check to make sure you have adequate chimney draft before building a fire.  To check the draft, hold a lit match or lighter up towards the bypass opening of the stove, if the flame pulls up, you have adequate draft.  If the flame is neutral or is pushed away from the exit, you will want to make sure you establish a draft before building a fire.  To establish a draft, you will want to preheat the chimney with a lighted twist of newspaper held under the bypass door.

            Second:  Put three short pieces (14’’-16”) front to back (North to South in stove-speak) behind the glass.  Placement of these pieces allows the air from the airwash to go under the rest of the wood, all the way to the back of the stove.  Insert some newspaper and small pieces of kindling in between these three pieces of wood.

                          Tip:  We save dry construction lumber for kindling (2x4s, or cut up old pallets).  Small thin pieces from the woodpile get added to the kindling supply, because small pieces will dry out quickly.

            Third:  Place three pieces of split wood across the bottom layer (East to West in stove-speak). Again, fill in the spaces with some loose newspaper and dry kindling.  This second layer of split pieces makes a platform for the third and final layer.  This platform should be 6”-8” above the floor of the stove.

            Fourth:  Build a small kindling “tented bonfire” on top of the second layer.  This “tented bonfire” should consist entirely of small pieces of split kindling – the drier (and smaller), the better.  As you build this kindling bonfire, put some newspaper in the middle.

            Finally, open the damper all the way, light the fire, and watch! 

            If you have one of our new hybrid woodstoves, and you are using dry kindling, you can close the bypass damper as soon as you see secondary activity on the fireback.  This usually takes place in less than three minutes.

            If you are using one of our classic catalytic stoves and you are using dry kindling, we have found that you can close the bypass damper in as little as 5 minutes.

            What to watch for:

            As embers from the kindling bonfire fall into the split pieces, the fire will gain in strength and intensity, until it reaches the split pieces on the bottom.  You will not have to open the door, or add wood.  The six pieces of split wood (weighing 10-12 pounds) will burn for several hours; longer if you close the damper down a bit after an hour or so.  You may have to experiment a little to get it just right.  There will be very little smoke or emissions if you start a fire this way.  You can see a video of us starting a fire this way in the lab here.  




            Stay tuned, this post gives you the “how", our next blog post explains the “why” it works so well.

            Wednesday, April 6, 2016

            April Steal of the Month: Tulip Mania!

            April has finally arrived and many parts of the country are enjoying Spring in all its glory. Tulips are among the first flowers out of the ground so it is not surprising that there are Tulip festivals this time of year from New York to Washington & Oregon, from Michigan & Iowa to Mississippi.  We thought we would do a bit of our own celebration of this first hint of spring by featuring the Tulip our Ideal Steel Stove.  

            During Tulip Mania, which peaked in 1637, only the wealthy could obtain tulip bulbs and the flowers. Now, in 2016, you can acquire your own tulips at a ‘steal’ when you take advantage of our Steal of the Month Sale and purchase an Ideal Steel Stove, complete with a bounty of tulips on the sides, top and even inside (andirons) your stove.

            Tulip Mania NAT020 • Click to Enlarge

            During the month of April, and only during the month of April, you can purchase an Ideal Steel Stove, complete with tulips, and all of the upgrades, for the low price of $2215.00, AND, you will also receive a FREE matching Tulip tool set.  

            Join us here at the Woodstock Soapstone Company in our celebration of the Tulip. Take advantage of our April, Ideal Steel, Steal of the Month and enjoy the beauty of Spring all year with the special artwork shown below.

            Click to Enlarge

            Tuesday, March 29, 2016

            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.

            Tuesday, March 22, 2016

            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?

            Wednesday, March 16, 2016

            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.


            Tuesday, March 8, 2016

            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.

            Wednesday, March 2, 2016

            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.