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Post in 'The Boiler Room - Wood Boilers and Furnaces' started by SE Iowa, Jan 17, 2008.

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  1. SE Iowa

    SE Iowa New Member

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    Hello all. I want to start burning wood in an outside boiler. I live on a farm in SE iowa and have plenty of "waste" wood right out my back door. I rent a farm also and spend a great deal of time "clearing" trees with the older farmer who ends up burning/wasting 90% of that in an un-insulated shop for his cats.

    Anyway, Central boilers are by far the most numerous in our area. I have friends who have them and absolutely love them. When I talk to the dealer though they always want to sell me the next to the biggest boiler. When I do the calculations though, I always end up with one size smaller (actually considerably smaller according to my calcs). If I compare my current actual NG (yes NG on a farm, lucky I guess) use I also confirm only the need for a much smaller unit. Admittedly, I want to start heating my garage and at some time will heat my basement. Right now though, my basement is at 67 degrees due to the type of heat and house that I have (see below).

    I built a 2 story insulated concrete form home with complete brick siding. I have ~R40-50 in the ceiling. I heat the house with in-floor radiant heat throughout the entire house excluding the garage (tho it has the hot water tubes in the slab). Above grade we have ~2850 sf plus ~1700sf below grade. I have 11 heat "zones" and shut off all the basement zones because the heat actually goes down too and so heats the basement to 67 degrees because there is no insulation/drywall up on the ceiling yet.

    Sorry so long. Anyway, I'm having difficulty swallowing that I need a 500,000 btu boiler when on the worst winter months I only use 180+/- terms. They tell me it will allow longer burn times because more water heated etc, but then won't it also require more wood/be less efficient? Any comments are welcome.

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  2. rsnider

    rsnider New Member

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    you dont need the bigger one if your house is that insulated. but the bigger one does hold more water and could benefit from all that storage of the water. just build small fires in the big boiler and it will be more efficient or just buy the smaller boiler and it will idle less = less smoke and more efficient. junk wood will work in a owb like central boiler but smaller loads of wood burning hotter will mean less smoke and less wood up chimney. good thing about cb you can line the bottom of boiler with fire brick for a little more heat in the fire box= hotter fires less smoke possible.hope this helps some. ryan
  3. Eric Johnson

    Eric Johnson Mod Emeritus

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    I'd be suspicious of a dealer trying to upsize your boiler choice. In my opinion, most dealers with your best interests in mind would tend to undersize before going too big. Usually they try to talk you out of an oversize boiler unless you can convince them that you know what you're doing.
  4. SE Iowa

    SE Iowa New Member

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    They tell me that if I use the smaller one, I'll be loading it more often. I'd like only to load it once per day, but if I have to cut/gather twice as much wood, then there goes my time/effort savings. What about these wood gassification boilers? Are they REALLY that much better so that they use much less wood? How often do they "usually" need to be loaded? It sounds like alot of people have hot water storage with these type. If that is the case, aren't they similar to OWB (i.e. OWB have usually large vol of water within them)?
  5. wsurfer49

    wsurfer49 Member

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    Welcome to the club! I am a newbie here too and have been researching heating with radiant hot water for several years now. I am convinced that a wood gasification boiler is the way to go. Some of the experienced people will respond too I'm sure.

    Anyway, the way I see it is that the gasification is more efficient and that in itself will make the whole heating ? easier. Less wood, longer burn times with a properly sized furnace. Water storage will improve the system but does not appear to be absolutely critical. I am still going to add a good sized storage system too though. If I were you I would look through the threads on the site and talk to some of the more experienced folk here. I think you will be pretty easily convinced and will ultimately be much happier with an efficient though initially more expensive system. Just my opinion. :lol: Rob
  6. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    CB tried to upsize me on a boiler. . .I am very fortunate that they 'lost' my name that year, then called me in January to ask if I still wanted their boiler. I said, "Yes, I want it delivered three months ago" The saleslady kept asking me the same question, and this obstinate prick kept giving her the same answer. Finally she hung up. Fortunate me. Very Fortunate.

    So I had to wait one extra heating season, but I got a much better boiler in the GreenWood. So far no storage. But don't listen to salespeople on storage. They will spin that issue to try to make a sale. To dummy-down the storage thing . . .

    It may make you slightly more efficient
    If done properly it may give you less 'idle' time
    It should make it more practical to burn during the transition seasons, and possibly summer.

    IMHO, if its mid January, don't buy anything now. Much as it hurts keep paying the NG bill and do your research. In the end, you'll be happy you did.

    BTW, are you hanging out there at the farm, you know, practicing good land stewardship and animal husbandry? Cause if you are, why is loading the hydronic three times a day a big deal?

    Jimbo
  7. SE Iowa

    SE Iowa New Member

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    Yes I am at home quite alot. I actually am a pharmacist 3 days a week just for the benefits (necessary evil). I started farming from scratch about 5 years ago. I do not come from a farming background + with my previous education it has been hard to obtain more acres to farm. I am hoping to farm full time at some point in my life. I don't have animals yet for the same reason that I don't want to load a fire 3-4 times a day. It ties you down. I have a NG backup boiler that I could use when we go on vacation during our sometimes long and boring Iowa winters. We are fairly involved with activities with our church and my farming after hours, and to be honest, my wife is not that interested in alternative heat sources. She would (although reluctantly) just use the NG and pay the bill. She just wants to be warm (she is the typical small built-feet always cold-lvoing wife). So, loading once daily is optimal for us. In a way, I think I've answered some of my own questions. I think a OWB or a gassification boiler wit storage would be the best for me.
  8. Eric Johnson

    Eric Johnson Mod Emeritus

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    A simple calculation (which is the only kind I'm capable of making) would suggest that a boiler that is twice as efficient will either burn half as much wood or keep you twice as warm, or probably some combination of the two. It's a generally accepted fact that a wood gasifier is at least twice as efficient as a typical OWB, so I think that should go a long way towards answering most of your questions.

    OWBs tend to have much higher rated heat outputs and water capacities than indoor boilers. I don't really know why that is, but I suspect that what they're doing is sacrificing efficiency for convenience: the less tending, the better. Don't confuse convenience with efficiency or clean burning.

    People who pay attention to their OWBs, burn dry wood and don't mind giving them more attention tend to see better results, but the things are designed for people who have access to a lot of cheap wood (hopefully they're going to burn wood) and only want to load the stove once a day. I think you can get away with once-a-day loading with most gasifiers in your climate. With a tank, you should be able to skip a day or even two in milder winter weather.

    As to the cold feet business, I just want to say that with fossil fuels, you're going to be cold no matter what, since you're always going to be turning the thermostat down to save money on your next utility bill. With wood, you pay less for your heat and you're a bit more removed from the economics, so it's less painful to keep the heat at a comfortable setting. She'll learn to love alternative heat when she can turn the thermostat up to 75. Heck, you're the one who will be doing all the work.
  9. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    Um, that's probably because yer a pharmacist, and money is no object.

    Then I suggest not trading her in. ;-)

    But I am confused about the cold feet. . . your house is all radiant, yes? Why are her feet cold? My dog hates radiant 'cause he can't find a cool place to lay down!!

    Jimbo
  10. SE Iowa

    SE Iowa New Member

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    Yes, I want to turn the heat up even more than I do now. I've mentioned b/f either here or in other post that we have radiant floor heat throughout house so we have mildly warm feet. But as I get older, I've notice I don't like to sleep with the windows open and like the temp 1-2 degrees warmer than when I was in my 20's. As far as the work, I clear trees from the farm I rent all winter anyway so the wood is "free" plus I actually love doing that kind of work (obviously since I went from being a pharmacist to a farmer). Or maybe its just that I'm cheap and hate being dependant on the big oil conpanies that just never seem to make any money and it is never their fault for the "shortages that cause high prices".
  11. Eric Johnson

    Eric Johnson Mod Emeritus

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    I'd say you came to the right place.

    Bear in mind that a gasifier setup is going to cost more upfront than an OWB. The payoff with the gasifier is less wood consumption and a clean burn. Everyone has different priorities and needs.
  12. SE Iowa

    SE Iowa New Member

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    My wife is a keeper for sure. She was just always had cold feet b/f I built the house we're in now. Everyone always gives us that, you're a pharmacist and rich so why should you care, but I think we ALL have to be responcible with what we have/consume. I can honestly say that there has been much happier times in my life (not that I'm not happy now) when I didn't have anything. I am not one of those far out save the planet minimalist either. Just someone who wants and has the means to go in a different direction.

    As far as the storage containers, I could not see much insulation on that thing. If I was to put it inside it would have to be 100% enclosed due to the tightness of our icf home we would grow mold in high heat/moisture environments. Outside, it would have to be super-insulated as we get very cold here frequently. It's supposed to be a high of -3 degrees tomorrow and a low of -15 on sunday morning (this is w/o wind chill).
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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    If you're concerned about the environment and can afford one, I'd definitely go with a gasifier of some sort. Sealing the tank is part of the deal--you can't have the thing steaming away in living space, so everyone with a tank has figured out how to do that. And don't forget unlimited, free domestic hot water. With the right tank, you can run the boiler once a week in the summer and have all the hot water you can use.

    There are many, many, hot water storage options. Pressurized storage (usually a 500- or 1,000 gallon propane tank) is one good way to go, but you can get into a wide vareity of different tank configurations--some DIY and some off-the shelf.
  14. Nofossil

    Nofossil Moderator Emeritus

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    There are lots of tradeoffs in this game, with virtually all of the options represented on this forum, and some of them vigorously promoted and/or defended. Here are some of the options that have been discussed here along with my choice on each. I really don't think any of these options are wrong. People have very satisfactory installations with just about every combination that you can think of.

    Boiler or hot air furnace? Most systems are boilers, but there are hot air solutions that work well out there.

    Indoors or outdoors for the boiler? I come down in the indoors camp because I like to tend it in my slippers. If you do it indoors, you want direct outside access to the boiler room for bringing in wood.

    Storage or no storage? I've done both and like having storage - more convenient and comfortable. Not a big improvement in efficiency for me, but because the boiler is indoors, I was already doing short hot burns even without storage.

    Gasifier or conventional? I went with gasifier for the clean burn and the reduced wood consumption. My brother went from a very clean burning conventional boiler to a gasifier and saw a 40% reduction in wood use. I heat 3500 square feet, DHW, and a hot tub in Vermont with about 4.5 cords a year, mid October through mid-April.

    Radiant / baseboard / radiator / hot air? I already had baseboards, but I'm adding a radiant zone. Radiant is a big benefit if you have storage, because you can use cooler water and still get useful heat out of it.

    Storage indoors or outdoors? I had no real choice on this one - outdoors for me. Has to be really well insulated, of course.

    Pressurized or unpressurized storage? I went unpressurized, mostly because I have a lot of in-tank hardware. You can get better performance and save a heat exchanger with pressurized storage.

    Circulator based or valve based zone control? Zone valves for me. I play a lot of games with the system controller, and zone valves make it easier.

    Series or parallel wood / backup installation? Parallel in my case, and probably best for most. Some installations put two boilers in series with a single circulator. Simpler, but at the cost of efficiency and response time in most installations.

    Primary / secondary loop or supply / return manifolds? I went with supply / return. Lots of discussion on this one. My prejudice tends towards the simplest design so that I can figure out what it's doing.

    All these are my personal observations and opinions. I'm pretty happy with what I ended up with, but it's by no means the only or the best way to do it.

    I've got pictures and a writeup on my site - link in my signature below.
  15. Eric Johnson

    Eric Johnson Mod Emeritus

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    And if you have no idea what he's talking about, hang around long enough, and you will.

    (Don't want to scare away the newbs.)

    That's a very good summary of the options, by the way, nofossil. Thanks.
  16. Gagz

    Gagz New Member

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    Thanks to nofossil and even with Erics disclaimer....I am scared...j/k . Had to get my first post out of the way because I have been lurking in total confusion anyway . It has been very entertaining though and I would like to thank everybody for their input and just want to say "hello" to all .


    Ray
  17. Nofossil

    Nofossil Moderator Emeritus

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    Welcome to the forum and to the boiler room. I wouldn't feel that I'd been pulling my weight if I didn't scare someone at least once a day ;-)

    Plenty of information here, some of it accurate. Take your pick and enjoy!
  18. webbie

    webbie Seasoned Moderator Staff Member

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    Hey, nofossil....

    Based on your experience, what do you think the actual delivered efficiency to the house is of an oversized Central Boiler?

    It might be smart to work backwards through the calcs to see how much wood it would take to produce the BTU's needed.

    Are there really any houses around that need 180,000 BTU in actual delivered heating? My house is 2800 Sq. ft in New England, and it uses less than 40,000 in the very coldest weather.
  19. webbie

    webbie Seasoned Moderator Staff Member

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    OK, lets think out loud
    150 therms in a regular cold month (if 180 in the very coldest).
    Is any gas being used for other purposes like gas dryer or stove- subtract some if so.

    So, 150 therms = 15,000,000 BTU's. divided by 30 days or 500,000 BTU's each 24 hour period.

    That is about 20,000 BTU per hour average into the water needed.

    Did I miss something here?
  20. Nofossil

    Nofossil Moderator Emeritus

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    At 30 below, I need 30,000 BTU/hr. Granted that some houses aren't as well insulated, but I have a lot of glass. Hard to imaging anyone needs more than 100K.

    Next question, though, is the difference between the advertised output and the practical / sustainable output. My EKO is rated at 80,000 BTU/hr, but in actual use I can comfortably run it at something more like 60,000 BTU/hr for any real length of time.

    As far as efficiency, there was a study that showed that most had a combustion efficiency of around 25% if I remember right. The EKO has been independently tested at over 85%, and I think the Tarm is in the same range. That's combustion efficiency, though. I'm actually getting more like 55% system efficiency. I expect that the OWBs with the buried lines and loss to the outside have much higher system losses, so I wouldn't be surprised if the system efficiencies were in the 10-15% range.

    At 55% system efficiency, I heat everything for about 4.5 cords per year. I'm fantasizing what would happen if I could get up to 70%.
  21. Eric Johnson

    Eric Johnson Mod Emeritus

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    Hi Ray. Welcome.
  22. webbie

    webbie Seasoned Moderator Staff Member

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    Wow, at 10-20% system efficiency, I think you should burn natural gas!

    Sounds like it is time to research some gasification boilers!
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