Tundra/Heatmax Information Guide

DoubleB Posted By DoubleB, Oct 27, 2016 at 10:08 PM

  1. DoubleB

    Minister of Fire 2.

    Mar 4, 2014
    NE Wisconsin
    The purpose of this post is to help users quickly find information about the Drolet Tundra/Heatmax, for example operation of the furnace, typical temperatures, cracking problems, control improvements, and helpful hints. Even if you don’t own a Tundra/Heatmax, you may find helpful general information, for example ductwork, chimneys, stove pipe, measuring draft, etc.

    At this time, the Information Guide is limited to information contained in the large thread, “Everything Drolet Tundra / Heatmax" starting here:


    This is not a comprehensive Information Guide of that thread. I tried to find a balance between general enough to quickly search, and detailed enough to help you find what you want. Sometimes I included a member’s screen name to help search for information they were associated with. It’s not professional quality, but good enough for this volunteer.

    If you have suggestions for additional or revised thread entries that should be included in this Information Guide, please send me (DoubleB) and/or Brenndatomu a message. In a perfect world I’ll have time to periodically update this Information Guide, at least to reflect the continuing contributions to the thread.

    Call this an Information Guide, Reference Guide, Table of Contents, Keyword Search, Lookup Table, or whatever you want. The idea is to help navigate and find. In theory, we could even link to and guide through other worthwhile Tundra/Heatmax threads if the opportunity becomes apparent.

    Tip: Instead of scrolling through dozens of pages of the thread to get where you want, go to the address bar and manually enter the page number you desire, for example, if you desire to quickly reach page 35, enter “35” at the end of the following url in your address bar:


    Everything Drolet Tundra/Heatmax Table of Contents

    Page Topics

    1 Introduction. Wisneaky’s install. Various operating tips and improvements. Manometer and static pressure. Backflow damper. DoubleB’s install

    2 Chimney liners. Redesigned damper flap (Wisneaky). Filter static pressure drop (DoubleB). 0.2 static pressure debate. Aluminum tape on blower housing. Blower noise level

    3 DoubleB pictures lowering furnace into basement., dedicated ducts for Tundra, peeling paint, flue temps with damper open/closed. BPWelding2005 reports the first cracking

    4 More cracking reports, pictures, and discussion

    5 More cracking reports, pictures, and discussion. Caddy comparison

    6 Squabbling about quality, cost, country of origin

    7 3Fordasho reports no cracking and describes his flue temp monitoring system and timer for initial damper open. SBI’s response to Wisneaky

    8 More SBI response, discussion about what they know vs. what they are describing. More flue temp controller. Damper door sticks open, needs tweaking

    9 Accumulated list of cracked furnaces and serial numbers. More SBI response and forum interpretation, questions about root causes vs. evidence vs. explanations. Heating load, cords per winter, house size, Tundra rating.

    10. More SBI response about cracking, forum discussion. Caddy comparison. Whether Tundra’s high limit snap disc offers good protection. How long to leave open damper.

    11. Caddy plenum vs Tundra dual outlets. Thermostat keeps damper open. More 3fordasho description of temp/damper controls. Idea of 2nd damper motor to keep damper partially opened. Amish use Caddy’s without blower or cracking. Estimated Tundra lifetime.

    12. Lifetime warranty. Replace the high limit snap disc to offer better temp protection. Cracking compared to damper link sticking open. Caddy false front allows airflow that cools front.

    13. Diagram and pictures of 3fordasho’s temp controller. Hi temp silicone on stove pipe. Soot on temp probe. DoubleB cracking opens when cold and closes when hot. Drill hole at crack root, fill with furnace cement. Brenndatomu’s salvaged Heatmax, and stainless steel front heat shield.

    14. DoubleB’s firebrick front heat shield. Types of firebrick/insulation. Static pressure and ductwork. SBI says cracking problem fixed, but not apparent how.

    15. SBI firebrick in new Tundras. 3fordasho’s 2nd install.

    16. When starting from cold, one outlet gets hot, the other stays cold. More 3fordasho temp controller specs. Discussion about firebrick retrofit kit.

    17. More discussion/solution about stuck damper rod. Builderml install up on blocks, discussion about tipping and ductwork.

    18. More tipping discussion. SBI introduces Drolet Heatpro.

    19. More Builderml install. Draft and barometric damper. Manual damper discussion. Matt78 install pictures.

    20. Ductwork discussion. First mention of Tundra II / Heatmax II.

    21. Flue temps with damper open and closed. On cold start one outlet is hot, other is cold. Front firebrick and damper restrictor plate retrofit arrived, pictures.

    22. More damper restrictor plate with dimensions. Secondary burn tube observations and exhaust odor. Builderml received his firebrick retrofit from SBI, without the damper restrictor plate, since newer Tundras had smaller inlet from factory. Brenndatomu temp controller and aluminum tape restrictor plate.

    23. More aluminum tape restrictor plate. SBI’s front firebrick crumbling. Matt78 mangled a chainsaw bar. 4-20mA modulating damper motor concept. Flue temps.

    24. Results of temp controller and restrictor plate. Ductwork configurations. Frequency of cleaning heat exchanger. Manual draft damper. Where to buy Tundra/Heatmax.

    25. Operating temps and snap disc cutout temps. Alternative overtemp snap disc settings. Multiple locations for overtemp snap disc. Risks of using thermostat. Brenndatomu’s Heatmax not producing heat. Troubleshooting cause.

    26. More operating temps and troubleshooting Brenndatomu’s Heatmax. NateJD’s install. Double-wall ceiling in firebox.

    27. More operating temps and troubleshooting Brenndatomu’s Heatmax, with pictures. Double-wall ceiling in firebox. Builderml’s chimney cleaning results.

    28. Laynes69 picture of Caddy heat exchanger inside plenum. Offgassing and burn times. More troubleshooting Brenndatomu’s Heatmax. Gap around blower housing. Brenndatomu removes sides from Heatmax and finds heat deflector.

    29. 3fordasho compares performance of 2 Tundras. Brenndatomu cleans heat exchanger buildup with torch. Smoke Signals recommends creosote remover. Sloeffle uses finishing nail to prop open damper. Brenndatomu adds 3rd outlet. Builderml tests different burning methods. More Brenndatomu troubleshooting and member suggestions.

    30. More Brenndatomu troubleshooting. Softwood, hardwood, coals, and KARB2014’s floor grate.

    31. Duration of damper open. More troubleshooting Brenndatomu’s Heatmax. Dodgemrj08 says SBI is now offering to pay for mobile welder to repair cracks.

    32. Dodgemrj08’s picture of new cracking behavior. Builderml battles coals. More troubleshooting Brenndatomu’s Heatmax, restricting secondary air inlets.

    33. More cracking pictures. Preemptive crack welding. 3Fordasho no cracking on 2 units with temp controller. Comparisons to Caddy.

    34. More Caddy comparisons and prices.

    35. More operating temps, ductwork, static pressure, airflow. How to measure static pressure. Operating watts.

    36. More on static pressure and operating temps. First discussion on turbulators.

    37. Brenndatomu’s turbulator pictures. DoubleB’s turbulator pictures.

    38. Brenndatomu IR picture of furnace. KARB2014 turbulator. Builderml methods of loading furnace. Builderml newer model furnace cracks, serial #1993. Cracking discussion and Caddy comparison.

    39. Differences between Tundra and Caddy. Difficult to clean a turbulator. Eureka!, Brenndatomu discovers cause of poor furnace performance.

    40. More Brenndatomu solution. Robotic welding. Reasons Amish can run Caddy’s with no blowers or cracking. Craig 9702 install and suggestions.

    41. Installing barometric damper horizontally. More installation suggestions, ductwork, chimney liners. Tundra II/Heatmax II plenum.

    42. First report of a Drolet wood stove cracking. Plenum discussion for Tundra. More Tundra II information from SBI. Modify Tundra I with variable speed blower drive. Revised SBI warranty.

    43. More operating temps. Variable frequency drive discussion. KARB2014’s plenum.

    44. Air jacket deflectors.

    45. Smoke Signals’s blower speed controller based on temp. SBI description of typical operating temps. Builderml trades Tundra for Max Caddy, appreciates SBI customer service. Brenndatomu’s plenum and air deflectors.

    46. Brenndatomu disassembles a Caddy. DoubleB snap disc overtemp protection and circuit diagram, and results of experiment to replace overtemp cutout snap disc. Benefits of timer to open damper. Variable speed motor options and conversation with motor manufacturer. Potential causes of cracking.

    47. Welds, cracks, updated Tundra I’s, whether cracking is fixed. Variable speed motor discussion.

    48. Digger79 reports on new Tundra. Digger79’s installation.

    49. Thermostat discussion. Which hot air outlets to use in jb616jc’s installation. Building a cold air return.

    50. Decline weld repair and request refund or redesigned unit instead. More info on what isn’t welded on Digger79’s new Tundra. How to burn locust and other woods.

    51. Burning hedge. Builderml’s wife filled firebox with coals. Digger79 installation pictures.

    52. Draft, with and without barometric damper. Different operating results. Types of chimneys, liners, insulation. Discolored chimney cap.

    53. Digger79 operating results. With and without barometric damper. 3Fordash controls description. KARB2014 resumes using coal grate.

    54. Hesitations about coal grate. Operating temps and drafts and burn times. Digger79 operating results.

    55. Infinitely variable speed blower. Whether to return unused Tundra. Digger79 install pictures with flex duct from garage.

    56. Quadrafire. SBI response to cracks. Getting jb616gc’s unit into basement.

    57. More getting jb616gc’s unit into basement.

    58. More SBI response. More draft and operating temps. Tundra II update, plenum, DIY installs. Canada prohibits parallel installs.

    59. More about Canada prohibiting parallel installs. Operating temps and results.

    60. Tax credits. More operating results, with a flue temp controller. How to identify the improved Tundra design.

    61. How to connect double-wall flue pipe. Square footage for Tundra. Original Tundra will be discontinued.

    62. Pricing for Tundra I and Tundra II. Tundra emissions. Builderml weld repairs.

    63. Pictures of redesigned welds. Discounts on discontinued Tundra I. Whether to use thermostat. Tstat wiring. Measuring flue temps.

    64. Temp probes. Condensation in chimney pipe. Whether to buy discontinued Tundra I.

    65. Cold air return filter. Guy988G smoke spillage, chimney, chimney connector info, elbows, and insufficient draft. Guy988G reports cracking.

    66. Operating with a cracked furnace. Jb616gc’s restrictive air filter and duct layout and temps. Filter size. Tundra price.

    67. Tundra big enough for TDD11’s house. Crewchief264 install. Variable speed blower. JustinE install. SBI tells Craig9702 to use thermostat that keeps damper open a long time. Ensuing discussion. Minimum amount of chimney connector rise. SBI replies to Guy998G’s cracked furnace.
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  2. begreen

    Mooderator 2.
    Staff Member

    Nov 18, 2005
    South Puget Sound, WA
    Great job DoubleB. Thanks for the putting this together.
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  3. MGerald

    New Member 2.

    Sep 9, 2017
    Thanks for such informative post doubleB.
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  4. 3fordasho

    Minister of Fire 2.

    Jul 20, 2007
    South Central Minnesota
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  5. Digger79

    Feeling the Heat 2.

    Jan 31, 2016
    wow! awesome job! kudos.
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  6. Digger79

    Feeling the Heat 2.

    Jan 31, 2016
    Well finally after 3 years I got the dang temp controller and probe dialed in properly. I initially ordered the wrong probe and fried it, then went thru a few store bought k type probes that came with electrical meters.. so the connections to the mypin can be a tad confusing specially when your trying to use the wrong probe and make it work. lol I got by for a while but finally got the proper J type probe and proper connections to mypin(thru trial and error mind u). To test accuracy of the probes I stick them under my tongue. lol. This one finally hit 98.6 exactly and balanced with other temp reading devices. my last probe went wacko and suited up the stove.

    In the move I inadvertently dumped all my gauge oil out of the manometer.. Is there anything you guys know of I can use other than ordering more gauge oil from dywer? I hate ordering crap on the web.
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  7. Digger79

    Feeling the Heat 2.

    Jan 31, 2016
    I understand the oil needs to have a specific weight to it and so I assume water will not work. Is there another oil I can use that will get me close to the weight of the gauge oil from dywer?
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