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7 steps for awesome operation of your Kuuma wood burning sauna stove

Medium Kuuma Stove

I have taken well over 6,000 saunas, and most have begun with me firing up the Kuuma wood burning sauna stove.

So, call me a “dedicated enthusiast.” I purchased my first Kuuma sauna stove in 1989. My cabin sauna, built in 1996 has a Kuuma. I built my first backyard sauna in 1998 with a Kuuma, then we moved and I built another backyard sauna in Minneapolis in 2003, yes, with a Kuuma. Also, I was volunteer lead builder of the 612 Sauna Society sauna, where we installed a medium Kuuma. I’ve helped Voyageur saunas get rocking with mobile and backyard sauna building… with the Kuuma! Most of my friends have a Kuuma.

I talk with many people and have never known anyone who has regretted purchasing a Kuuma wood burning sauna stove.

I’ve built more than a dozen saunas, all with the Kuuma. And through my ebook, I have helped hundreds build their own sauna, and, yes, you guessed it, many have installed a Kuuma. Matter of fact, if my wife would let me, I’d put a Kuuma sauna stove in our living room.

7 steps to fire up and operate your Kuuma wood burning sauna stove

  1. Start with a clean fire box. Pull the ash out of the firebox, down into the ash pan.  Use the tool that Daryl designed.
  2. Logs. Lay 5-6 logs into the firebox. Lay them in parallel like you would stacking your woodpile.  Ideally load firewood a bit higher on the sides, lower in the middle, creating a “U” or pocket.
  3. Paper. Light a crinkled sheet of newspaper or birch bark. Set atop the logs in the firebox.
  4. Kindling: lay a few sticks on top of #3.  (Note: It took me 28 years to learn the upside down fire!).
  5. Leave everything alone for 45 minutes: damper up, ash pan closed.
  6. Pull coals forward. Then toss on a “yule log” for sauna, if needed.
  7. Damper down. You’ve reached Kuuma nirvana when, as you look through the glass window, you see the “dancing blue flame.”(1)
Firewood for a sauna, left. Kindling for a sauna, right. (haircut sold separately).

There is something counterintuitive about wood burning

Controlling the damper controls the burn rate. And, less oxygen will slow down the burn, but it will also contain more heat within the fire box. Therefore, when you have achieved a good fire in the fire box, we create more heat in our saunas by dampering down the stove. Generally speaking, when our saunas are up to about 150°f., this is about the time to begin dampering down.

There is an incredible amount of science that goes into the design of the Kuuma wood burning sauna stove. So, if wood burning efficiency and sauna stove design is something that interests you, I encourage you to listen to my 2016 Sauna Talk interview with Daryl Lamppa.

Glenn interviewing Daryl Lamppa for Sauna Talk. (note pads sold separately).

BONUS: 4 Tips for operating your Kuuma wood fired sauna stove.

  1. Use dry seasoned firewood.
  2. Use dry kindling.
  3. Pull your coals forward before tossing on a stick of firewood.
  4. Damper down as you get close to “serving temp.”
Medium Kuuma Stove
The Kuuma Wood Fired Sauna Stove (flames sold separately)

(1) “The dancing blue flame” is actually smoke gases that are turning to flame, or combusting. This process occurs when the temperature inside the fire box is high enough and air flow low enough. So, slowing down the air flow with ample heat is what creates the proper atmosphere for what is called gasification. Building stoves that can reach gasification is an art and a science. Achieving a clean burn is something that Daryl Lamppa, 3rd generation sauna stove builder, has spent his entire life studying, optimizing, and achieving through decades of testing and iterating.

We welcome your ideas and experiences in comment section.

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28 thoughts on “7 steps for awesome operation of your Kuuma wood burning sauna stove”

  1. We’ve snowmobiled to Fortune Bay Resort two years in a row now. The first year we were one of first to use
    their mobile sauna with a Kuuma stove which at that time was located at the front entry. Great heat after a hundred mile ride and we even got filmed for a marketing video. Last season it was moved down to the
    marina which was about a half a mile away. The ride back in just our swimming trunks was one of the best cool downs I’ve done. Great stove and a great place to stay just talk to Garrett who has the right connections to
    Kuuma.

  2. I’d like to add that I have worked in metal fabrication industry for over 47 years and these stoves are built. I’m very impressed with the craftsmanship and quality and the heat they put out.

  3. Greetings, thanks for all the information.
    We are currently building a sauna in a horse trailer and in the beginning stages. The inside has been stripped, rust treated, and is ready for insulation and framing. I have Reflectix ready to go, however, I have a few questions. The ceiling is metal. Should I put the Reflectix on the metal and not use any other insulation? We were going to cover the roof in the framing, but have limited room to move, as it is 30 sq/ft and 6’4 high ceiling. Is the Reflectix sufficient?
    We bought the book which is great, however some aspects are coming from the point of view of a wooden framed construction, whereas our shell is a bit different.
    I’ll put some pictures up to give you an idea.
    The side wall is wood about 3/4 the way up. Is it best to put the Reflectix right onto the wood? It’s been sanded and treated.
    I’ll have a few more questions along the way. Thanks everyone, we’re pretty excited to for the journey ahead!
    Cheers!

    – G.A

  4. Hi GA,

    I’ve helped with more than a few horse trailer saunas. In a few of the instances the procedure has been:
    1. closed cel spray foam.
    2. super premium glue and self tap screws, 1×2 firing strips to existing framing.
    3. t&g.

    Now, the off gassing police (as opposed to the more German style aufgussing police) may want to blow their whistle on this method, in which case, we’ve applied foil between the existing framing and nailers.

    I like this, as our wall cavity is open one time, and we can hermetically seal this one time.

    Now, the “trap moisture” police (as opposed to some other style police) may want to blow their whistle on this method, in which case, we point out that the skin of our trailer won’t let in moisture, and the well sealed foil barrier won’t let moisture in, so we can sleep at night with this.

    So, this probably isn’t addressing exactly what you’re asking, but above is what I know best and others may chime in.

  5. I’m building a backyard sauna using your book for guidance. Thank you BTW!! Building the shed myself, which is nearly done. Now planning ceiling, stove & pipe placement. I built a low pitch (1/12) lean-to roof and appear to have a rafter in the path of a straight chimney. A couple questions:
    1) another recent post in ST suggested a low pitch (<6/12?) does not leave enough attic space for the insulation box. Is that true?
    2) With the rafter and possible attic space issue, should I consider a 90 degree turn and through wall chimney kit? Any concerns with that approach? It seems easier to box out the wall than mess with the roof.

    Thanks for your suggestions!

    Stephan

  6. Stephan:

    I’ve been there! A rafter in the path of the straight chimney feels just like getting a flat tire on your bike ride. Bummer! But just like with a tire patch kit, we can fix it! And the fix is in the spirit of:

    “we build our saunas one time, and get to enjoy them the rest of our lives.”

    1. low pitch insulation: If we frame with 2×6, we can get R19 between the joist cavities. If we want to think crazy, how about 1/2″ polyiso atop our roof sheeting, thereby a little more oomph up there? And thermal break for good measure. Warning: free range organic orthodox tradesmen police poo poo polyiso. (note recent post, and it’s worth thinking).

    2. 90 degree turn in stove pipe and go through the wall: I’ve never done this! I avoid 90 degree turns like I avoid the extra hot sauce as Chipotle. It doesn’t sit well with me. I see it as a liability to try to get a draw going every time I fire up my sauna stove, with that twist and turn. Now some may have great results with the 90 degree program, but I’m a straight up vertical chimney type guy (stubborn mule).

    What I would do:
    1. Print the template for your Kuuma stove. Link to print the PDF is here.
    2. Mark and plumb bob for the center point for your chimney pipe.
    3. Build a 12″x12″ box out of same framing material as your roof framing (2×6 or 2×4)
    4. Hold the box and mark where you’ll need to cut that rafter.
    5. Take 5 Wim Hof Breaths.
    6. Cut your rafter. Sawzall.
    7. Cross brace frame to your two adjacent rafters, to properly support your broken rafter.
    8. Screw in your 12″x12″ box.
    9. Cut out your roof sheeting with Sawzall.
    10. Keep rocking with stove install.

    I know how much it sucks to have to mess with your rafters. Again, i’ve been there!

    But you can do this.

    And every time you fire up your sauna stove, then settle into round one on your bench and see your straight up chimney pipe, you’ll be happy you did the A job. BONUS: nobody will ever know there is a broken rafter up there (except you).

  7. I like to start with smaller/thinner pieces of wood with thicker pieces added on top once the fire is roaring. Once the initial burn brings down the pile, I add another armful of wood (I have a medium Kuuma.) Although not necessary with the Kuuma, I use a chimney damper. I close down the damper part way (maybe 2/3 shut) at between 180 and 200 (I like a very hot sauna), then close the air intake on the stove down to about 1/3 open. I think this helps keep the heat inside the stove, vs. allowing it to go up the chimney and out of the sauna. This usually really brings the heat up in a hurry and results in a peak temp of 210 to 220+ in my sauna, which will last for two hours or more without adding wood. I find raking the coals forward once the hot fire begins to die down tends to lower the temp slightly, but provides a mellow heat from the “dancing blue flames”. An interesting observation is that when I increase internal ventilation by sliding my windows open more than a crack, the stove seems to run even hotter given better oxygen intake.

  8. Hello neighbor,
    Excited to find this blog! I just purchased a house with a sauna (electric heater) in the basement in south Mpls. I don’t believe the heater is working and would like to have a full inspection to checkout everything. I’m having a hard time finding who could do that. Do you have any recommendations for sauna inspection/repair companies in the metro area? I appreciate any help, really anxious to get everything working before the cold comes!

    Thanks!

  9. I’m trying to buy a cedar vent chute on your site and it keeps giving me an error message saying that I need to select a shipping method. Please advise.

  10. Hi Glenn,
    Have been firing up the ” Pirts O’ Plex ” ( Latvian for Sauna Plex) since we completed it in November. After reading this ” 7 Step ” blog I have to ask if step 5, ” leave everything alone, damper open for 45 minutes ) does or does not conflict with your previous ( and the Kuuma instructions ) to only burn wide open for 5 – 10 minutes before lowering to normal burn position D.

    ” DO NOT OPERATE STOVE ON THE HIGHEST SETTING ( DRAFT LEVER ALL THE WAY UP FOR A LONG PERIOD ) THIS WILL RESULT IN EXCESSIVE HEATING OF THE STOVE AND COULD DAMAGE THE UNIT. ” Per the Kuuma instruction manual and same as the instructions you gave me when we picked up the stove. Seems they would think 45 minutes would be a ” long period. ” What am I missing?

  11. Hi Glenn and Everyone. Jake here, from Vermont. I have a 2 story, 180 year, brick old home with a three-chamber fireplace with flues running to each floor (upper, ground, and cellar). The home is cold during the winter (with uninsulated walls), and I’ve been wondering if it’s possible to meet stove installation standards and run a six inch insulated stainless steel liner through the cellar’s chimney flue chamber to a chimney cap (about a 35′ ft run) and build a fire-safe interior sauna in the cellar. The cellar runs around 38 degrees in the winter, so capturing leftover heat from the Sauna is appealing. At one time, the cellar’s unlined flue appears to have been used for a wood or coal furnace, but has since been converted to hot water heat. I have seen some Nordic cottage/camp designs with the sauna integrated into a living structure (not a stand-alone building). If you know of a stove that could function with a long chimney run or examples where this has been done, I’d love to learn about it.

  12. Hi Jacob:

    Dale at Lamppa Mfr. in Tower, MN can detail for you the long chimney run/constraints. We do this all the time with the Vapor Fire wood burning furnace. He’ll be a wealth of information for you.

    In terms of building your sauna within your brick home, I want to encourage you to begin thinking about enveloping your hot room in its own thermal envelope. If in a basement with any kind of damp environment, we want to be thinking about rigid insulation (vs rockwool or standard batting), and 250°f. rated poly-iso foil or foil vapor barrier, and air gap and paneling.

    You can follow along within the ebook Sauna Build: From Start to Finnish.

  13. Glenn,
    I live in Roseville, MN. I am converting a shed into a sauna and was going to install the 16CK wood stove – from FinnSisu… made by FinnLeo. I checked with the Roseville permit office and this was their response:

    Thanks for the installation instructions for the unit you’ve chosen. In searching for documentation on the units testing and listing with an approved agency I have attempted to contact Finn Sisu and was unable to reach them as the voice mail box was full. I instead called Finnleo directly and was told by I believe an engineer within the company that the unit selected 16CK has no testing or listing. He did pass me on to another individual for further confirmation if there was testing or not and I left message for him to call me back.

    It is prohibited in the state mechanical code to install an unlisted device of any kind no matter the fuel type or its purpose. This would include a wood fired sauna stove. I will wait for the return call from Finnleo, but wanted to give you a heads up on the latest information.

    SO… I am in a bit of a quandary. Maybe I shouldn’t have checked with the city and just flown under the radar. But I did… and I am surprised that a stove made in Cokato is not legal in MN! Can you help me figure this out?
    Thank you .
    Doug

  14. Hi Doug:

    Bummer about all this. We are working on an article right now that will be of interest to you. It’s a guest post from Jeff C. an electrical engineer who is extremely knowledgeable regarding electric sauna heaters, sizing, etc. Please stay tuned on this. PS.. Jeff C. wrote a two part article that if you haven’t yet read, please do so here.

  15. Hi Glenn
    I have Kuuma stove water tank boiling problem bringing humidity level really high. Any suggestions? Temperature is 220-240F

  16. Hi, I have a question. I have the opportunity to buy the large kuuma stove from someone local who never finished their sauna. Can a the stove be too big for the sauna. We’re thinking of a max of 6×8.

  17. Hi Scott:

    I wouldn’t put a large Kuuma into a 6×8 hot room. It’d be like putting in a jet engine instead of a ceiling fan to ventilate your changing room.

    And unless you’re thinking of setting up a Canoe Outfitters lodge, it probably is going the wrong direction to build a 10×12 hot room to size your room to the large Kuuma. Selling a Kuuma is no problem, they don’t show up much on the secondary market and when they do, they’re gone the next day. So, I’d encourage moving that stove through and investing in a small, ash pan, glass window, heat shields. You can order one through me, same price as at the factory, if this helps you along.

    Wishing you good sauna,
    g.

  18. Hi Slava,

    You’re keeping the lid on the Kuuma side water tank I trust?

    You must be one of those Russian sauna guys where anything less than 220f. and you’re reaching for a spring jacket, right?

    If steam is getting out of your water tank, boiling like a kettle on your stove, the only other solution is to run your water tank dry. I know this is a buzz kill, and against the intent of the side water tank, but that level of heat and high water temp. isn’t practical to the function of the Kuuma water tank.

    Both my Kuumas have water tanks. My sauna sessions (2-3 hrs. 200f.) don’t reach the level of temp. to start boiling the water in the water tank. Towards the final rounds, the water gets hot, but not “let’s make a cup of tea” hot, so, you’re taking things up a notch for sure.

    (Note to self: if Slava invites me to sauna, remember to sit in ice bath for 20 minutes before I show up).

  19. Hi Glenn,

    Aside from the official setbacks for a small Kuuma, for an uninsured shed, what would you say is a reasonable, off the record, setback from:

    – Water tank to a cedar bench?
    – Water tank to non combustible with a 1″ gap?
    – Heat shield to non-combustible with a 1″ gap?
    – Heat shield to cedar bench?

    Many Thanks,
    Matt

  20. Matt, well, being that I am typing this on Saunatimes, well, there is no “off the record” setback.

    There is a nod, nod, wink, wink though. I will say, in the cobbler’s kid’s shoe department, that both my saunas – cabin and backyard – do not prescribe to UL setback requirements. That’s 1996 and 2003, respectively, and thousands of sauna sessions.

    Water tank to cedar bench: very close.
    Water tank to non-combustibles with 1″ gap: very very close.
    Heat shield to non-combustible with 1″ gap: close.
    Heat shield to cedar bench: pretty close.

    We want to be practical, and safe. And that’s the way I have approached my sauna buildings. When I build for others, and sell Kuumas, I recite the official setback requirements. (7″ from heat shield to wall).

    Don’t mean to be vague about it, and you can look on Saunatimes YouTube and you’ll see my saunas.. Good sauna Matt!

  21. Glen, I recently completed building a sauna based on your plans. From the ground up. Ittook forever but it turned out sweet. It gets crazy hot in there. My fist sauna in it it was 220 degrees. I know now that’s just a bit outside the normal range. I have now made the correct adjustments to the stove. I also found out that you can melt the coating on your eye glasses in a sauna. I have a question on sauna thermometers. I bought two and tested them out in the sauna. The first one cracked the glass during that first sauna and the second one was cheaply made. I sent both of them back. Do you have any recommendations on sauna thermometers? Seems like there are a lot of poorly made ones out there. Thanks, Mark

  22. Mark,

    I hear you. Not only are there a lot of poorly made thermometers out there, but most are a rip off.

    Stay tuned. Give me 30-60 days, please, as I’m on a mission from God. If I had $1.00 for everyone who has asked me about a good sauna thermometer, I could buy us a couple cases of beer, and enough gas to deploy a mobile sauna in the foothills of Aspen CO, adjacent to a snow melt mountain stream. We’ll get there!

  23. Glen, Thanks for looking into the thermometers. Also I tried to order a side heat shield from the website but it wont let me process it. I can pick it up as I live near you. I have a small Kuuma Stove and I don’t want to burn my legs anymore. Mark

  24. Stephan,

    To go around a rafter where your chimney should go, you could try using two 15 degree angle parts on the chimney. Adding short sections in between the angles you can generate any offset you need. This is also good for fine tuning the stove location after the chimney is in place – by rotating the chimney assembly and adjusting the angle parts you can move the stove front/back and side to side. I have done this twice, works great.

    John

  25. Glenn writes “I talk with many people and have never known anyone who has regretted purchasing a Kuuma wood burning sauna stove.”

    I’m frugal, and enjoy fabricating. When I started building, I thought I’d try building one of those propane tank stoves, or adapt a cheapy from northern tools. My partner researched and talked me into the kuuma, which we picked up from Glenn. This was easily the best choice we made (other than deciding to build a sauna, of course).

    We used an oven thermometer at first, before finding something more aesthetically pleasing online.

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