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Bi Metal Thermostat

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by jrprusak, Dec 11, 2010.

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  1. jrprusak

    jrprusak Member

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    I am still having a hard time giving up my 30 year old Earth Stove with a "bi metal thermostat" for a newer EPA unit. The thermostat is a great feature to have on a wood stove.. The only new EPA units I see around that have a thermostat are the Blaze Kings. Are there any other units out there with a thermostat??

    I am surprised thermostats are not on more stoves that are meant for full time operation.

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  2. SteveKG

    SteveKG Minister of Fire

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    I've been looking into Hitzer stoves, the Amish-made wood and/or coal stoves and inserts. They have models with bimetallic coil air inlets, don't know whether they are EPA, but they look to be very-well made and designed. I have a Shenandoah with the coil, works very well but also not EPA.
  3. begreen

    begreen Mooderator Staff Member

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    Blaze King stoves have a thermostat and so do Vermont Castings stoves.
  4. Battenkiller

    Battenkiller Minister of Fire

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    I think thermostats on most wood stoves would be mostly ineffective. There is way too much lag time between the introduction/reduction of intake air and a meaningful temperature response to that air. Never used a Blaze King, but the one on my Vigilant does very little to regulate the stove temperature. I wish I had complete control of the air, and would prefer not to have to share this responsibility with an inanimate object.
  5. kenny chaos

    kenny chaos Minister of Fire

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    Having considered it before, I now believe my stove would blow up before
    the thermostat could close the damper and adjust the air.
  6. begreen

    begreen Mooderator Staff Member

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    I wonder if your Vigilant's thermostat is broken or just tired. We had the same on our old Resolute and it worked great. The stove was in a small house and would have driven us out if it didn't work well.
  7. savageactor7

    savageactor7 Minister of Fire

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    Our 2 Shenandoah's stoves had bi-metal thermostats and I was very pleased with them. They offered a simple 'low, medium, high' burn rate and that was sufficient ...

    ...we did go threw quite a few thermostats IIRC, like maul handles I always bought 2 at a time. But they did open and close the intake air. All things considered I have to throw in with our new stove even though I was forced into upgrading and very happy with the r77.
  8. begreen

    begreen Mooderator Staff Member

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    I think the Hearthstone I & II had a bimetal thermostat too.
  9. jetmech

    jetmech Member

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    My Intrepid II has a thermostat on the primary air. If stove gets close to 700 stove top it will move the air shutter torwards close . It also has a secondary air shutter in the rear which operates by a coil which senses Cat outlet temp.
  10. fishingpol

    fishingpol Minister of Fire

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    I had a VC Aspen with one in the back. I had the stove in my fireplace opening. That spring had the damper closed way to much due to the heat staying in the firebox causing the spring to lower the intake door. It would be better for a stove outside the fireplace freestanding in the room. Pretty good idea that it can self regulate itself to some degree.
  11. jtb51b

    jtb51b Feeling the Heat

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    Until recently my blaze king thermo worked flawlessly.. I CAN NOT regulate this stove the way the t-stat did, originally I could get good heat output for a good number of hours and then all of the sudden it was all or none.. My stove is less than a year old and blaze king is sending me a replacement part, unfortunately they are 7-8 days off via UPS.. Boy I can't wait until I get this thing back working right, its working (and worrying) me to death.

    Jason
  12. Renovation

    Renovation New Member

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    It looks like the upcoming Woodstock Firecat will have some sort of thermostat too.
  13. LLigetfa

    LLigetfa Minister of Fire

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    I realize this topic is about free-standing stoves not fireplaces but I like having a bi-metal control on my RSF. No, it isn't quick to respond and so isn't completely idiot-proof but I like not haivng to monitor and fiddle with the control constantly. Then agan, I'm not a complete idiot. Some parts have gone missing. %-P
  14. jrprusak

    jrprusak Member

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    Mine on the Earth Stove with the thermostat has work flawlessly for 30 years, it’s a light it and forget it stove, even heat all the way.

    At the woodstove store yesterday the salesman did say all the burning models in the store have to be adjusted down once they get up to working temperature after reloading.

    So those without a thermostat, do you have to adjust the manual control to keep even heat during the burn and throughout the day??
  15. nate379

    nate379 Guest

    Yeah Blaze King for sure is a "set and forget" stove.
  16. Todd

    Todd Minister of Fire

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    I don't know if a thermostat would be such a good thing for my stoves. I tweak my air setting a couple times at the beginning of the reload and I just leave it alone for the next 6-12 hours and I get a nice even burn. I'm thinking a thermostat is a good thing for those large fire box stoves that hold a ton of wood to help keep them in check and the whole load from outgassing all at once?
  17. Battenkiller

    Battenkiller Minister of Fire

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    They wear out? Never heard that before.

    Anyway, I broke mine clean off when I got the stove last year and had to order a brand new one. I set it exactly how I was advised by the local VC gurus - half open (45º) when the stove is dead cold. It opens and closes the intake flapper just fine, but the temp at that particular location is not always in sync with what the rest of the stove is doing. Plus, there are many times in horizontal mode where closing the intake a bit actually causes a rise in temperature. That closes the door more, which eventually lowers the stove temps when I really want them to stay up there, with the likely additional expense of less efficient combustion. Sure isn't the "set it and forget it" control that I hoped for. I seemed to get better control manually with the jury-rigged adjustment method I used while my thermostat was on order.

    I feel that if thermostats were that effective, the major makers would be all over them. It's not cutting edge technology or anything. Personally, I never use air control as a method of temperature control, I use it as a way to get an optimum burn. Load size and recharge frequency are much more effective in controlling BTU output, at least on my stove.
  18. begreen

    begreen Mooderator Staff Member

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    It's been many years, but the way I recall running the stove was to leave the thermostat flap open until after I had engaged the bypass and the stove had settled into the long burn. Then I'd set it so the flapper just closed when the room temp was about right. At that point I could walk away until the stove needed refilling. But I haven't done that with the Vigilant. My brother's Vigilant's thermostat (and bypass) was broken, so it was manual operation only. That worked sort of, so maybe you're right. I don't fiddle too much with the air control on the T6 either.
  19. Renovation

    Renovation New Member

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    That seems a very valid conclusion, and I pondered it long and hard--why don't more manufacturers use thermostats, when they work so well on some stoves (Blaze Kings, etc.)?

    Here's my theory, submitted for your approval.

    With the advent of EPA stoves, stoves became more finicky and thermostats became more problematic. Secondary burn is critical for stoves to meet the EPA emissions limits, and anything that might throw them out of secondary burn is a problem.

    Primary air and efficient burning is clearly an issue, and many have complained that they can't shut their EPA stoves down enough with their strong drafting chimney due to the "Bungalow Effect". To pass EPA, stoves have to burn clean in conditions simulating a Florida bungalow--low chimney and relatively high outdoor temps, which means poor draft. So stoves have their primary air control configured so that someone in a FB can't choke it out of secondary burn, which means someone with a good drafting chimney may not be able to turn down the stove enough. I've seen a number of such posts.

    This is particularly an issue with thermal (non-cat) smoke burners, for a not-too-low stove temp is required to keep the secondaries firing. This is less of an issue for cat stoves, which can ignite smoke at lower stove temps (once the cat ignites, it gets warmer).

    Likewise for thermostats--finicky EPA stoves may fall out of secondary burn if a thermostat cuts back the primary air. So perhaps the explanation is that it is a PITA to get an EPA stove to work with a thermostat, that cat stoves do it more easily, and getting an EPA stove to work with a thermostat is a relatively sophisticated and new technology?

    We do see Woodstock, who has a reputation for making sophisticated cat stoves, hinting about putting a thermostat on their next stove.

    Thoughts?
  20. SolarAndWood

    SolarAndWood Minister of Fire

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    The thermostats in both of our VCs were ineffective at best. The BK thermostat produces a very predictable burn and is very quick to react to something like turning the blowers on or off. It adjusts within 30 seconds.
  21. jharkin

    jharkin Minister of Fire

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    George,

    I think your theory may explain why the only stove makers that use thermostats (BK and VC) are catalyst stove makers. As long as the cat is lit off its much harder to close the air so far that the secondary burn dies on a cat.
  22. corey21

    corey21 Minister of Fire

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    When i had the wondercoal stove in my house it had tstat on it and produced a steady burn. One thing that i miss now.
  23. jetmech

    jetmech Member

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    The thermostat on my VC intrepid works just fine... i have seen it cool the stove and not let it get to 750 and have watched the secondary shutter keep cat temps below 1900.... im glad it has these devices they are good saftey measures built into the stove, My stove is older a model 1303.. still looks good and runs great
  24. jrprusak

    jrprusak Member

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    I just found an interesting article about the Pacific Energy "Extended Burn Technology" bi-metal draft control that automatically operates the draft control similar to a thermostat on the older stove. It operates on its own so there is no operator adjusting. Check it out… There is a link at the bottom of the article to actually see it in operation.

    http://www.chimneysweeponline.com/hoebt.htm
  25. Wood Heat Stoves

    Wood Heat Stoves Minister of Fire

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    lennox stopped supporting these old smoke dragons. they are horribly inefficient!!

    might be a good time to upgrade, unless chopping wood is keeping you healthy.....
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