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Did efficiency really go up when switched from stove to boiler?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Bster13, Jan 28, 2013.

  1. Bster13

    Bster13 Minister of Fire

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    Looking over the efficiency of EPA wood boilers, I'm seeing 90%+, and looking at some of the CAT Stoves I see 80%+. Do you think you burn 10% less wood while keeping your house at the same temps? The reason I ask is because you lose out on radiant heat when you switch to a boiler, and I'm not really sure how the EPA or companies measure efficiency. Thanks!

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  2. maple1

    maple1 Minister of Fire

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    I'm not sure you can get a good handle on things comparing a wood stove to a boiler. A wood stove is a space heater while a boiler provides central space & hot water heating. If I was heating my house with a wood stove, I would likely need 4 of them plus live with a very cold basement to have the same level of comfort I have with a boiler & baseboard heat - and spend another $40/month to heat my DHW.

    EDIT: How would you lose out on radiant heat with a boiler? I've got all kinds of it coming from my rads - and storage tanks in the basement.
  3. Bster13

    Bster13 Minister of Fire

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    The DHW is a nice benefit as well. Forgot about that one. I guess for the average house (say <2k sq ft) I'd be interested in folks experiences. Sounds like you have a large home.
  4. maple1

    maple1 Minister of Fire

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    2700 sq.ft. on two stories.

    I realize a boiler isn't for everyone - but I'd have cold spots all over the house with only 1 stove, no matter how much air I got moving around. I also don't like air moving around. Might be just me.

    A small-ish one story house with open floor plan would be quite well suited for a stove, I think.
  5. avc8130

    avc8130 Minister of Fire

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    I have gained efficiency with a boiler. Here is what I mean:

    With the wood stove I would have to stuff it FULL 3x/day. I would have to hang around ~30-60 mins to be able to adjust the air down. It would "heat" ~1/2 my house and oil did the other. I had to run the oil for the DHW.

    With the wood stove, I put wood in it 2x/day. I am able to tend my boiler in less than 4 mins each time. I get 100% of my house heated AND my DHW.

    If that isn't more "efficient", I don't know what is.

    ac
  6. heaterman

    heaterman Minister of Fire

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    Short answer.......No.

    Please be aware that there are no wood fired boilers that will hit 90+% efficiency. It is a physical impossibility to run a wood fired boiler at efficiencies which would demand condensation of the flue gas. It can be done in high quality pellet boilers due to the extremely dry nature of the fuel which allows low flue temperatures.

    For all practical purposes of comparing a wood stove to a boiler system, a good quality wood stove will be at least equal to the boiler in terms of efficiency. This is due to the fact that installation, piping, and control of the wood boiler along with insulation of piping and storage can heavily influence how well the system delivers heat to the space. There are many ways to screw up a boiler system while a wood stove just sits there and heats via convection and radiation into the space around it.

    As others have mentioned, efficiency can mean a lot of things when you consider the whole picture. Even heating in the entire structure being one of them. This is very hard to do with a conventional wood stove. Wood boilers can vary widely in the amount of attention they need ranging from a Garn needing about 15 minutes a day and cleaning once per year to having to babysit a downdraft gasifier running with no storage several times per day and cleaning it weekly.
    Consider the whole story and how much you want to be married to your wood burner as you make your decision.
    Some of the pellet boilers coming on the market right now are very attractive when you lay all the cards on the table.
  7. Bster13

    Bster13 Minister of Fire

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    I was comparing the efficiencies list here:
    http://www.blazeking.com/EN/furnace-apex.html

    vs.

    http://www.blazeking.com/EN/wood-princess.html

    Even heating is a factor, but hoping my 1974 sq ft. home can heated evenly w/ a stove, but not sure.

    DHW is a factor I did not consider initially, good point. Maybe a passive hot was heater would supplement there.

    The boiler installation is a great point as well.

    Babysitting the burn is another factor. Not sure why stoves don't yet have the computer control the boilers do yet. But hoping a Blaze King Princess with the bi-metal thermostat... while not controlled like a boiler, would be "pretty good."

    I also have a fear of not being able to troubleshoot and fix problems myself with a boiler vs. a stove with less moving parts.

    Pellets are off the table me, as I enjoy scrounging free wood. We'll see.
  8. BoilerMan

    BoilerMan Minister of Fire

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    I can say like avc, that i use less wood with my boiler than with my stove. I have a Quadrafire 4300 ACT series in my living room. It can easily heat my house with the stove if it's above zero. This said I use way more wood in the stove, and that doesn't heat my DHW. Keeping a fire going 24/7 and raking coals and vacuuming ash..... not nearly as fun. We do like the stove during the shoulder season and for quick heat if I've not fired the boiler in a few days for some reason.

    Very happy with the Quad overall, and nice clean burn.

    TS
  9. goosegunner

    goosegunner Minister of Fire

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    What I like about my boiler system is the control of the heat. The temperature in the home is even and controlled by the thermostats for each level. At night you can turn it down for sleeping and warm it during the day to whatever temps you choose. Today it will be 57 degrees here in WIsconsin, Thursday it will be 10 degrees. If I set my stat at 70 it will be seventy both days, I will just burn more pounds of wood on the cold days to recharge storage.

    My dad and brother have wood stoves, they don't burn wood on days like this. Even on colder days their house will be 80+ degrees at times in some areas and much colder in others.

    gg
  10. Bster13

    Bster13 Minister of Fire

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    That is a concern...I don't want to be heated out of my living room. My hope is the bi-metal thermostat in the Blaze King can help bridge the gap between a precisely controlled boiler and a secondary air EPA stove. I hope to visit some folks in the area with this stove to get a real feel.
  11. slowzuki

    slowzuki Feeling the Heat

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    Even running an old pre-epa woodstove going to an efficient boiler I figured my wood use would increase. Why? Because I'm going to keep it evenly warm throughout the house and time of day. Right now the fire goes out and house cools off overnight and during the day.
  12. woodsmaster

    woodsmaster Minister of Fire

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    Don't think you will save much of any wood with a boiler, but you will be more comfortable than with a stove.. A stove is a much cheaper investment though so it depends on how much you want to spend to save money and be comfortable, If that makes any sense.
  13. Couderay80

    Couderay80 Member

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    When drinking beer I can sit in front of my wood stove longer then in front of my boiler. Maybe someday I'll figure it out. ;)
  14. topoftheriver

    topoftheriver Member

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    I'm right with you brother. I have both, one for uniformity and the other for estetics and of course heat. I really don't care one way or the other. I am not burning more wood either way but I am enjoying it more. As for the beer--------you bet and along with my guitar and turn the lights off in the evening, the music even sounds better.
  15. ihookem

    ihookem Minister of Fire

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    I had a Quadrafire 7100. It heated my house ok at best. A 2200 sq.ft ranch. It was toasty in the family room ( 70's) but 58 in the far corner master bath. Now I have an EKO 25 gassifier. The fmily room is 68 and the far corner bath is 65. Much better. I slept better with the fireplace cause the bedroom was cold. That is the only thing better about the fireplace except it was nice watching the flames.. I burn almost the same amount of wood but have DHW now, so it is a bit more efficient.
  16. Bster13

    Bster13 Minister of Fire

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    I can't figure out what the difference between an EPA wood insert vs. an EPA wood fireplace. Can someone explain that?
  17. Duetech

    Duetech Minister of Fire

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    For me efficiency is rated by the amount of wood I currently burn compared to the amount of wood I used to burn. I have had two wood add-on furnaces, one OWB (ceramic by advertisement) and two gasifiers (one indoor and one out door which is my current model). The gasifiers easily burned only half or less than half of the wood the other heat systems did with fewer trips to the stoves and less ash residue and much less smoke. That means less cutting, splitting and stacking and more time for fishing and breathing easy. That is so efficient I can't even put a number on it but I got a grin all over it.
  18. Bster13

    Bster13 Minister of Fire

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    Was your wood stove EPA certified?
  19. Bob Rohr

    Bob Rohr Minister of Fire

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    There are a number of gasification type woodstoves on the market, quite a few choices in Europe. Here is one brand sold by a dealer in NY. Generally the fewer heat exchanges the more efficient the heater. With a wood boiler the wood is combusted releasing the chemical energy, which is transfered to the water, then to the heat emitter and transfered again to the space being heated with radiant, conduction and convection transfer.

    With a wood stove it's fire to steel and radiant and convection. So if the combustion efficiency is the same, say 80%, then you need to look at the distribution efficiency.

    Comfort is another question, with central hgeat you can get more even heat to the various rooms and control room temperatures with zoning. With a wood stove you depend on thermodynamics of hot traveling to cold.

    Reminds me of a plumber friend I worked with that lived in NW Montana for many years with a fire in the middle of his teepee! Aside from smelling of smoke all the time, it was a comfortable, affordable, and efficient heating system.

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