Specs and Detail Information for the Zaug Stove

Zaug Altaire
Zaug Altaire shown in Metallic Blue

Each Zaug is custom made to order.  There are over 50 individual pieces of steel welded together to complete one stove.

The Fabrication Process

The 12 gauge cylinder and 2″ trim must be rolled and welded. Then the inner chamber and bottom plate is formed. After that, the insulation chamber is formed and welded. Once all the welding is complete, the surfaces are sanded, washed in lacquer thinner, and primed for paint. A coat of Thurmalox 2-part zinc primer is applied and allowed to dry for 24 hours. Then, two coats of Thurmalox paint is sprayed to a 2 mil thickness for a smooth finish. The final touch is an optional coat of Thurmalox high temperature clear lacquer for a gloss finish. Fabrication takes approximately 34 days from start to finish.

Below is a video showing one small part of the fabrication process; How the cylinder is made:


Feed tubeIn our tests, the Zaug Standard burns about 1 cubic foot of wood in 4 hours. If you consider that a pound of wood has 8000 BTU’s (acceptable rate per Sam Foote P.ENG.), and there’s 21 pounds of wood in a cubic foot (Pine or Fir), then the amount of heat given off after burning a cubic foot of wood is 168,000 BTU’s in 4 hours. That doesn’t mean the stove gives off that amount heat, it only means that, 168,000 BTU’s was produced by the fire. Some heat will travel out through the exhaust to the outside air, and some heat will travel in to the home radiating from the stove. Now, if you can capture at least 90% (most rocket mass heater/thermal mass units capture 95-96%) of that heat created, and retain that heat within your house through the thermal mass and exhaust line retention, you will have approximately 151,200 BTU’s of heat over 4 hours. That’s 37,800 BTU’s/hour produced from sticks and branches.

There’s 128 cu. ft. in a cord of wood, burning 1 cu. ft. a day, would yield approximately 128 four-hour fires. Or, 128 days of warmth. A four-hour fire is enough to heat up your mass and nearly heat you out of your home.

The standard Zaug Stove operates best with sticks and branches, but the Altaire can handle 6” rounds up to 20” long. The fire eats a hopper of sticks and branches in about 30-45 minutes in the Standard, and 1 – 1.25 hours in the Altaire (depending on how long your mass is, what type of wood burned, damper door setting, etc.).  A solid round of hardwood will burn in about two hours.

The Exhaust

Zaug Exhaust
The exhaust is ran horizontally. If encased in a thermal mass such as brick or clay, this thermal mass will heat up and store the heat for many hours.

We have tested our exhaust up to 47 feet before we change the direction to vertical. However, at 47 feet, we experienced some backdrafting and very slow exhaust movement. We recommend the exhaust be shortened to 25′ to eliminate back drafting and maintain optimal flow from the unit. Adding a vertical section at the end of the run, dramatically increases the draw through the system.


The Thermal Mass

Thermal Mass
Shown here is the 6″ duct being placed inside the thermal mass. Cob is being packed around the duct.

The most beneficial way to use a Zaug stove, is to add a thermal mass around the stove exhaust, to capture and store heat from the exhaust. The easiest way to do this is to make a bench or hearth out of cob or clay. Brick or masonry can be used for a bench or mantle as well.

Shown left, we have built a cob bench in a barley growing room. The exhaust duct is in the center of the cob. In your home, the bench would likely run along a wall and can be used to sit or lay on.

For more information on how to build a thermal mass, research Rocket Mass Heaters on the internet.

Glass (Altaire Model Only)

Altaire Glass
The new Altaire offers a glass lid on the feed tube

By far, the most appealing feature about the newly designed Altaire has got to be the glass lid for viewing the fire. The Return Air Port System allows air to flow in to the unit from the grated side grills, thereby, allowing the feed tube lid to be closed while in full operation. This glass is a 6″ x 9″ window made of 9/16″ thick Neoceram heat resistant glass. It’s capable of withstanding temps of 1200 °F (648.88 °C).

For Greenhouses

For heating greenhouses, the exhaust duct can be installed in grow beds, or in specific situations the soil, so that it runs approximately 6 inches underground to heat the soil. The soil or grow bed will act as a thermal mass and retain heat for several hours. If you have an aquaponics system, you may even consider wrapping a coil around the Zaug exhaust to heat the water in your system. The exhaust duct temperature is approximately 225 degrees. Extreme care would have to be taken to avoid over-heating the fish.


Standard Zaug shown in Antique Ruby and Flat Black.

The cooktop of the stove can be easily removed for access to the interior, for quick cleaning. There is an easy-access ash pit, resting in the pedestal, for removing burned ash. The air-intake chamber over the feed tube, on the Standard Zaug, is dampened down and can be completely closed off with the bi-fold hinged door on the top of the intake.

It is not recommended to install a Standard Zaug in a basement situation where the basement is not the main relaxing area. The reason is that the Standard Zaug needs more attention than a conventional wood stove, and therefore should be placed in an area where it can be watched and filled readily. A better choice would be to use the Altaire with a one-hour burn time.


CloseupZaug Stoves can be custom built to your liking. Among the different options we have, are:

  • We offer custom placement of the exhaust port anywhere on a 90 degree swivel, left or right. When designing your system, tell us where you want the exhaust line to go and we can accommodate your needs. For instance, if your stove sits in a corner, and your thermal mass runs along a wall at a 90 degree angle, we can place the exhaust port to exit the stove right where your mass starts.
  • For dual exhaust runs, we can weld dual ports on either side of the cylinder. This might be helpful for greenhouse applications or a secondary port for a priming run.
  • We offer a cold air return port placed in the base of the pedestal. This port will allow air to come in from outside or wherever you choose.
  • We offer many styles of ash pit drawer handles.
  • We offer many colors to choose from.
  • For extra paint protection, we can spray a clear lacquer coat to give a gloss look and an easy surface to wipe down.

Shipping Details

Raleigh Blue
Altaire shown in Raleigh Blue with Midnight Blue Trim

Stove weight is 340lbs (154.22kg) for the Standard Zaug and 420lbs (174.63kg) for the Zaug Altaire. Shipping weight is 440lbs (199.581kg) for the Standard and 520lbs (235.868kg) for the Altaire.  The shipping crate weighs 120 lbs. We ship from Yelm, WA 98597. We use a shipping broker for our shipping needs in continental US and Canada, and Old Dominion for our ocean freight voyages.

Fabrication takes approximately 34 days from start to finish. Please be patient if we go over by a couple days. We tend to get orders in waves, and it becomes a challenge to keep on schedule.


Not Intended For Wood Pellets or Wood Chips

Wood chips and pellets are a manufactured product thereby, chaining you to purchase a product that was created and packaged using fossil fuels. The Zaug has been designed to be free of manufactured products, thereby using less fossil fuels and helping the Earth be more pollution free. We are advocates of living sustainably.

Click here to see the 2014 the Owner’s Manual for the 2014 Zaug Altaire

Owner's Manual


Comparison of the Standard Zaug to the Zaug Altaire:

Standard Zaug Altaire
Price $2,100.00 USD Discontinued $2,584.00 USD Discontinued
Height 42” (106.68cm) High 42” (106.68cm) High
Diameter 21” (53.34cm) 21” (53.34cm)
Stove Weight 340lbs (154.22kg) 420lbs (174.63kg)
Cooktop Weight 30lbs (13.61kg) 32lbs (14.52kg)
Cylinder 12ga. light carbon steel 12ga. light carbon steel
Combustion Chamber 7 5/8” square x 3/8” (19.36cm square x .9525cm) Steel tube 7 5/8” square x 3/8” (19.36cm square x .9525cm) Steel tube
Insulation Chamber Welded 16ga. sheet steel filled with 2” Perlite volcanic rock Welded 16ga. sheet steel filled with 2” Perlite volcanic rock
Ash Pit Drawer 5” x 5” x 8” (12.7kg x 12.7kg x 20.32kg) Black Steel Handle 5” x 5” x 8” (12.7kg x 12.7kg x 20.32kg) Stainless Steel Handle
Feed Tube Opening 6.25” x 7.5” (15.875cm x 19.05cm) 7.25” x 9.5” (18.415cm x 24.13cm)
Return-Air Port System Optional Complete RAPS
Feed Tube Glass Door Optional Yes
Cold Air Return Port Optional Optional
Primer Thurmalox 245 Zinc Primer Thurmalox 245 Zinc Primer
Finish Thurmalox 270 High Temperature PaintOptional High Temperature Clear Lacquer Thurmalox 270 High Temperature PaintOptional High Temperature Clear Lacquer
Colors 8 Standard Colors (Optional 16 more with $50 charge) 8 Standard Colors (Optional 16 more with $50 charge)
Operating Temps Cooktop Plate 450-800°F (232-426°C)Cylinder 250-500°F (120-260°C)Exhaust 90-200°F (32-93°C) Cooktop Plate 450-800°F (232-426°C)Cylinder 300-500°F (149-260°C)Exhaust 125-290°F (51-137°C)
Exhaust Port Size Standard US 6” HVAC Duct (Optional sizes for Europe) Standard US 6” HVAC Duct (Optional sizes for Europe)
BTU’s 37,500/hour 40,000/hour
Fuel Source Dry wood, sticks, branches only. No Pellets Dry wood, small rounds, wedges. No Pellets
Fuel Size Up to 4.5” (11.43cm) solid rounds 18” (45.72cm) long Up to 6” (15.24cm)  solid rounds 20” (50.8cm) long
Burn Time 30 – 45 minutes per hopper 1 – 1.5 hours per hopper
Warranty 3 Years / Parts and WorkmanshipExtended Warranty available 3 Years / Parts and WorkmanshipExtended Warranty Available
EPA Certification No No
UL Listed No No
Shipping Weight 440lbs (199.581kg) 520lbs (235.868kg)



We are in the process of certifying the Zaug Stove with the proper EPA and UL regulations; However, at this time, the Zaug Stove is not recognized as a conventional wood burning stove by the EPA. Unfortunately, the EPA does not have a test for this new type of wood burning technology. It may be some time before an independent research and development team can design a test for our stove. Thank you.

25 thoughts on “Specs and Detail Information for the Zaug Stove

  1. please email me additional information or you can mail it to: Deleted for Privacy

    1. Please provide us with an email address and we will be happy to send you a digital brochure.
      Thanks for your interest in Zaug Stoves.

  2. How many BTU over the four hour burn period are produced by the Zaug?
    I currently heat a house with a large wood stove in the basement – three floors, 2800 sq feet. My chimney is 26′ long.
    Would the Zaug with thermal mass be able to heat my house here in VT?

    1. I’d like to invite you to watch this video- http://www.youtube.com/watch?v=4usXIAoy9us
      These people have built a rocket mass heater themselves.
      To get the kind of heat out of the stove that you need, the stove would definitely need to be used in combination with some sort of thermal mass which will extract and store heat created from the stove. A thermal mass can even be a vertical rock chimney, as long as the exhaust duct is zig-zagged through the masonry. The more heat you can extract from your exhaust duct, the better efficiency your stove will have. The BTU’s are difficult to calculate when you include a thermal mass in to the calculation, since the thermal mass gives off heat as well (continuously for up to 24 hours).
      However, I wouldn’t recommend using the 26′ chimney for your exhaust run. The air inside the exhaust duct will cool down, and it won’t have enough heat to push up 26′. I’d suggest using a new exhaust port and sending the vertical line up about 10′ instead.

  3. I’ve seen external wood and/or coal furnaces which pipe hot water to a house, the aim being to isolate the house from the risk of fire. Seems to me the Zaug could be positioned just outside and the exhaust piped through the wall and into thermal mass. Might keep the building inspectors happy.

  4. To RayS: I’ve seen that type of outdoor solid fuel furnace also. Although it might make the inspectors happy – someone has to feed the external furnace… I do like sending heat – but not fumes – into the home. Wood smoke does cause a certain amount of sickness – http://www.epa.gov/burnwise/healtheffects.html & people with asthma & compromised lungs are more at risk.
    The reason I originally became interested in the rocket mass stove is that – as a nurse – I noticed a correlation = the problems of 2 million deaths of women & children worldwide resulting from open fire cooking together with deforestation – and how this relates to our own energy future – more expensive, dangerous & toxic methods of extraction & more demand.
    I wondered whether there was a common solution for heating that might work for cooler Latin American countries & for us in the Northeast US.
    I love the masonry heater – but so expensive – can’t be popularly retrofitted in our area… & the UL certification on that – not sure.
    The Rocket Mass heater might help solve cooking and home warming problems in the third world – and maybe home warming and water heating problems here in the US.
    I wonder…
    To Jim Pitman – I have the same situation approximately – I have a Vermont Castings Defiant that amazingly heats our entire 3 story house very well – but we feed it 5 – 6 cords of wood = its a lot of work…

    I would LOVE to see Rocket Mass Heaters applied to RADIANT FLOOR HEATING – and it is a good question whether that heater could be fed pellets via an auto feeder AND kept in a small heating shack outside the house.

    Meanwhile – good luck with UL cert – & I will buy one when you are certified!

    Yours with warm regards

    1. I was researching using a rocket mass type heater for hydronic radiant floor heating, myself. I did find a commune that built a shower house using a rocket heater. Instead of an insulated flue inside of a larger container (55 gallon drum) to force the hot gases back down, they used an insulated flue that rose nearly to the ceiling and turned back down to force the hot gasses down through a natural gas style water heater, down to the ground, and then out the side of the exterior wall. It seemed effective, and any condensate would run down the inside of the water heater’s inner flue and towards the outdoor exhaust, instead of back towards the rocket heater or getting caught in a crevice.

      1. sounds interesting. I’d love to see some pictures of this. Would you site the source?

        1. Hmmm, I can’t seem to find it now… Never did save it as a bookmark, sorry. I’m certain that it was set up just that way, like an oversized pocket rocket. It was still insulated, an then the flue was turned to force the exhaust down through a gas-style water heater, from the top down. I’m also certain that the reason for this was to permit any condensate to drain away from the setup and out of the building. It wasn’t really being used for space heat, so much as to heat water for a communal washhouse for a hippie commune. Or ‘intentional community; if you prefer.

    2. With rocket stoves, the exhaust (after the initial few minutes) should be very clean. It shouldn’t cause any breathing problems. Check out some YouTube videos on building your own rocket heater to get more details into how it works.

  5. I have a wood stove that i would like to change out and put in a mass heater. but my only way to vent is into my existing chimney.was thinking about coming out the back of this heater to the chimney running 6inch pipe horizontally across going back and forth and then to my chimney.Going to cover 6 inch pie for thermal mass would have about 15 foot of chimney left . Do you think this design will work

  6. well house heater

    We use a rocket mass heater for our well house heat.

  7. i built a stove like a Zaug stove here in this cold town Cuenca Ecuador thank you i will send a photo soon

    1. Can’t wait to see it!

  8. Finally a company that puts their money where their mouth is and EXPLAINS the whole thermal expansion and contration principle behind their stove. One thing I would add is an emphasis on the difference between radiation heat and tempreature. More specifically in terms of low and high frequency heat transmission and it’s effect on heat perception.

    Besides that. One of the comments above refers to an all night long burn, or the lack thereoff. I have a similar stove, just not as neatly build as the Zaug one, and I use flax straw with a gravity feed system on that. The flax straw can be replaced by any other fine granulated solid fuel that is locally available as long as it’s caloric value does not exceed that of wood, being rougly between 6 and 7.5 thousand BTU/CF, as that would melt out the burnchamber too fast.

    So for what it”s worth. Good luck with your business, stay safe and enjoy the heat.

    Kind regards,


  9. What is the price on these type of heat stoves? And they be used in my house or my garage?

    1. The current cost of the stoves are $2100-$2584 USD. They can be used where ever a conventional wood stove can be used. Check with local codes for approval.

  10. Please consider a mini Zaug for mini cabins and campers….. Thx I p

    1. We have a mini Zaug designed… Just need to raise enough funds to have it certified. Thanks for the comment!

  11. Hello my name is Robert.
    I am going to build a greenhouse 50ft width x 90ft length and 12ft height.
    The average temperature needed is 60-75 degrees F.
    What is the thermal mass needed heat my greenhouse and will your Rocket Mass stove be suitable?



  12. Hi I forgot to mention that I live in a cold climate so would need to maintain this thermal heat from 6-12 hours during the 3 colder months.



    1. Hi Robert,
      This is going to take some research on your part to calculate the heat loss in your greenhouse, along with the material you want to use for your thermal mass. I wish I had a simple answer for you but there are so many variables. Check the forums and see what others in your area are doing.

  13. I’m a Newbie, but find this idea fascinating. Hope to hear soon that your regular size & proposed Mini Zaug are approved. I plan to build a16X20 cabin with a loft & I’m afraid the regular size may be too hard to keep from overheating the cabin. I’d also consider replacing a wood burner in a 14X70 mobile home I have.

  14. What is the life expectancy of the Altaire? I know the warranty is 3 yrs, but what is the expectancy, providing we don’t ruin it by overheating? How does this warranty compare to traditional steel wood stoves? And do you have a video on how to clean a rocket mass stove? I read multiple directions, but still can’t get a clear picture. One more question…I still have concerns as to how well it will heat our 34′ off-grid yurt on the Kenai in Alaska. If you care to do some experimenting with us next winter, we are in the market for a stove, but aren’t yet convinced that a rocket mass stove can keep up with our winters here (our Blaze King is on its last legs). It would be a really bad thing to discover too late that it wasn’t up to the job. On the other hand, it could be great advertising for you if it handled it well 🙂 Let me know!

    1. Hi Joanne,
      The Altaire is obsolete. We have designed a brand new model that will take it’s place if we can get the EPA certification and the UL listing. Right now, we are not manufacturing any stoves until this goal is achieved.
      However, I can tell you that our stove has been tested in Whistler Canada, where it heated a two-story home, without a thermal mass. The stove performed better than expected providing heat, but the amount of labor to keep the fire going was increased, since there was no thermal mass acting as a battery to store heat.

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