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Thinking of replacing my old Tarm

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Onfoot, Dec 3, 2011.

  1. Onfoot

    Onfoot Member

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    Just discovered the forum, and have been enjoying reading through the postings from the past several years.

    I have been benefitting from a wood gasification boiler for 9 winters--a much beloved Tarm Solo Plus 40. However, two years ago I completed a guest suite above the garage/mechanical building, effectively adding 1200 sq.ft. to our heated living space (now a total of slightly more than 3000 sq.ft.).

    The Tarm is able to keep up with the heat needs, but only just, and not able on cold days (-20C and below) to add enough BTUs to the heatsink to prevent the oil boiler from needing to kick in between going to bed and getting up, or going to work and returning in the evening. So I am looking at replacing the Tarm. (I should say that I have been very happy with it and it is still working great in every respect. My only complaint has been that it smokes when firing up and loading. Creosote is almost non-existent.)

    For a variety of reasons, I am down to deciding between an Econoburn EBW200 or 300 or the Frohling FHG-L50. But I would love to benefit from the wisdom on the forum around some of my thinking.

    As I see things, part of my problem with the Tarm is the size of the firebox (5.4 cu. ft.). If the firebox was twice as big, the BTU output would keep up (even if just barely) with the heat loads. My reasoning is that, even at -40, if there is wood in the boiler, the 850 gallon heatsink temp is not going down, and is typically gaining some. (Please correct me if I am mistaken in my reasoning.)

    The Econoburn EBW200 has a firebox volume of 8.1 cu.ft.. The Frohling FHG-L50 has 7.4 cu.ft. Given that I do not like raising my heatsink above 165F, my guess is that the burn control features of the Frohling would allow me to get maximum BTUs out of my load of wood, but as a straight line transfer as opposed the bell curve of the Econonburn. (Though to be fair, the Econoburn also controls its burn via temperature sensing.)

    There are other considerations as well. The Econoburn needs an 8" chimney and the Frohling needs a 6" chimney--which is what I currently have. As well, living off-grid as I do, power consumption is an issue. The Econoburn has a 175W fan at 110v, which is 1.6 amps. The Frohling draws 180W at 240v, which is .75 amps.

    FYI, we do not have hardwood in this part of the world. I burn spruce and pine, with some poplar in the shoulder seasons (it generates a lot of ash, but there is always lots of standing dead on the property to clean up).

    Anything that I am missing or should be thinking about?

    Thanks for sharing your wisdom!

    Barrett

    Attached Files:

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  2. Duetech

    Duetech Minister of Fire

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    I am certainly not the guru you need for the complexity of your query but I can welcome you to the forum! Curiosity has me wondering if the btu limitations you impose on your system are system related or preferentially based on circumstances of availability of time etc.etc. and not that I really need to know. Whatever it seems boosting your storage/heat sink to 180*f or 190*f would initially give you a little more lee way with the tarm but with The EBW 200 or the FrolingL-50 it should give you a much better level of security. Larger capacity combustion chambers should give longer burn times but given a greater btu output you may find the need to adjust the amoungt of wood you are burning to avoid idling. Which actually may be a pleasant problem instead of perplexing like your poor thermometer that most of the dye has leaked out. :wow: Once again...welcome to the forum.
  3. Onfoot

    Onfoot Member

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    Thanks, Pyro, for your thoughts. Re. the storage/heat sink temp, there are two issues with respect to increasing it. First is that the rubber bladder life span is significantly reduced once you hit 175. (The 'tank' is what was sold by the Tarm folks in Lyme 10 years ago--works great, but the rubber will wear out eventually--though not too complicated to replace.)

    Secondly, and equally important, is that once the heat sink hits 170 or so, it ceases to work as the 'radiator' for my genset, causing the genset to trip its 'Murphy switch' to prevent overheating. I actually need to be a bit careful managing the boiler burns and the likely generator charging cycles.

    We do have a problem with leaky thermometers, as you noticed. :lol:
  4. toothy

    toothy Member

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    Hello Barrett

    We sure do hang about in some strange places!!!

    I'm with Cave on the higher temp storage. Maybe you could do something else with the gen heat sometimes, have it valveable, made up a new one there, where you could valve it to the tank or some baseboard, or outside?

    I picked up 2, 500 gallon tanks from Amerigas over by your brother, cheap. I don’t know if they would fit in your space or if you could get them across the border? Going pressurized seems like the way to go. You could get enough out of your heat exchanger to pay for the tanks with copper being so high. I’m going to stack mine the regular way but you could cut the end out turn the end upside down and weld it back in as a foot to take up less floor space.

    I welded up an approximately 1000 gallon tank to use as storage then didn’t like the price of the exchanger coils so I’m getting ready to start welding the propane tanks together.

    I’ve just started using my Tarm Excel 2000 a month ago without storage, yet. It is only rated at 102K on wood and I can see it taking a good while to get the tanks up to temp when they get installed. I didn’t buy the Excel for this house but it seems to do the job, for now. Mine also lets out little whiffs of smoke like yours.

    I wonder if there exists a more simplistic, less power hungry boiler that burns correctly, smoke free that is. As a side note have you seen the power figures on the Grundfos Alpha pumps.

    If one of my thermometers ever did that, I would move away and leave that thing behind!


    Wade
  5. carbon neutral

    carbon neutral Feeling the Heat

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    Hello,
    You certainly have a lot of cool stuff. I was wondering why you don't consider going with a cascade system. Use your current tank for low temp i.e. your solar tubes and generator heat sink then as suggested above use propane tanks for pressurized storage off your wood boiler. You heat zones pass through the low temp storage first then through the high temp storage. Your solar collectors will pick up more usable heat if they are generating at say 120 degrees and your generator will be able to run for longer durations if needed when the storage starts out at a much lower temperature. Certainly the cost of propane tanks, I paid $250/ea for mine, would be much less than buying a new boiler and you gain efficiency in the bargain.
  6. jebatty

    jebatty Minister of Fire

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    I'm starting my 5th winter with my Solo 40. With 1000 gal pressurized storage, I don't have the heat sink issues you have. It is easy to load the entire storage to 190F, top to bottom. That said ... the Frohling FHG-L50 is one sweet boiler. I likely would have considered it if it had been available when I bought the Solo 40.

    I am just gaining experience with the Frohling FHG-L50 this heating season. Loading and then lighting it couldn't be much easier, and then walk away. Although I'm still exploring the flexibility of the computer controller, I know you can easily set maximum temperature, although I don't know how low you can go, and as the boiler and/or storage approaches the maximum, the draft fan dials down to reduce output. You also can, I am advised but have not done it, dial down the output burn rate to the output levels of the 40 or 30, maybe even the 20. Assuming this is correct, this adds additional flexibility in allowing a longer burn time between loadings at lower btuh output. This might be exactly what you want.

    Other posters have indicated that they think the loading unit is undersized. The one furnished with the L50 I have experience with has a maximum flow rate of about 12 gpm, which at delta-T=20F amounts to 120,000 btuh continuous, in contrast to the 170,000 btuh rating of the L50. It is a matter of opinion as to whether this is undersized, as at delta-T=30F, btuh=180,000. The way I look at it is that on heat sink charging delta-T > 20F, and the unit is not undersized, and then as the wood load burns down and btu output falls, the loading unit remains adequate. Regardless, there is an easy and quite inexpensive fix to this if the need is for greater btu transfer, and that simply would be installing a circulator like a 007 in parallel with the loading unit, controlled by an aquastat, mechanical or electronic, set to "on" at 160F or greater, perhaps 175F, on return from system/heat sink. In this way extra flow would move the high end btu's, bypass the loading unit, and still retain return water protection.

    As with all hydronic systems, proper sizing of the piping, determination of pump head, and selection of circulators is very important.

    You have a envious decision to make. Wishing you the best.
  7. Dune

    Dune Minister of Fire

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    Signature
    Partner: Happily married 4 decades and counting.
    Toys: Kubota RTV900; Bobcat 7753; F250 4x4 diesel.
    Tools: 2 Stihl 260, one with 20†and one with 16†bar. 1 Stihl 032 with 16†bar.
    Heat: Tarm Solo Plus 40 boiler, Viessmann Oil Boiler, 850 gal. Heat Sink, 88 tube solar collector, 2 Vermont Casting woodstoves, one Jotul woodstove.
    Power: Off-grid system, 1400 amp hour, 48v battery bank, 4kW solar panels, 2.5kW Proven wind turbine, 6kW Kubota diesel genset (that adds its heat to the heatsink, instead of a radiator).
    Home: 20 acres in the Yukon bush, on the banks of the Yukon River.

    I found your problem, it is not your boiler, it is your genset. 6KW just doesn't produce enough waste heat.

    Just kidding, I am slowly but surely bringing a 25 KW generator on line. You are way ahead of my curve, congrats on a job well done.

    Why are you against storing heat at above 165?
  8. TCaldwell

    TCaldwell Minister of Fire

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    Pine and spruce, both being pitchy softwoods also add to combustion complexity, they burn fast and hot, with more volatility than hardwoods. Not all boilers regardless of lambda comtrolled or not can sucessfully accomplish this. I would hope you could locate your boiler choices and run a load of your wood through each in your consideration criteria.
    tom
  9. maple1

    maple1 Minister of Fire

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    If electricity consumption is a major factor, have you checked out the Varmebarronens? Some of them don't have any fans and operate on natural draft (although you do need a tall chimney).
  10. Duetech

    Duetech Minister of Fire

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    Onfoot... Tom from Maine (you can do a search for one of his postings to do a pm to him for pricing) has a new liner material that is supposed to be able to handle the higher temps without theusual problems with rubber if you decdide to stay with non pressurized storage. He can have a liner built to your spec's. It sounds like the gen set circumstances are being well considered...Great!
  11. goosegunner

    goosegunner Minister of Fire

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    The only way you are going to add time between loadings with a bigger boiler is to idle more.

    If you have a higher out put boiler it will charge your tank to 165 faster. So you would have to get it to 165, and then reload letting it idle on and off to maintain that temp until wood is gone. Not really the best way to run but maybe it would only be done that way on really cold days.

    It would be nice if you could dial the Froling btu output down so it was a slow steady burn. That way you could take longer to charge tank which in turn would give a shorter time you would need to run on storage alone....

    Does that make sense?

    As much as I like my Econoburn 200, if I had a boiler in my house I would want a induced draft not a positive pressure fan.

    gg
  12. goosegunner

    goosegunner Minister of Fire

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    Now you have me thinking, I wonder if you could run a Econoburn 200 like a 150. What would it do if you had the nozzle from a 150 and ran a smaller fan or a slower speed. Maybe it would give the longer burn time with a larger firebox.

    gg
  13. Onfoot

    Onfoot Member

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    Had composed a very detailed reply to all the posts, only to have it eaten by an internet hiccup. Ah well. One more time...

    Thank you to all for the helpful input! (And fancy meeting you here, Wade!) Some useful things to consider.

    As you will see from the attached photo of my heatsink (the lid taken off when I added a heat exchange loop for my genset), I have invested in a lot of copper! I am a bit nervous about doing more than upgrading the liner--perhaps something to do this summer. (Thanks for tip about the Maine fellow.) The rubber liners tend to become brittle once the temp hits 175. And their life span is typically about 10 years--so coming to the end of mine either way. I do not have room to add more heat storage as per one suggestion, unless it was on top of the current tank--perhaps a possibility, though then I need to think about all that copper... (I have an old 5000 gal heat exchanger sitting in the yard from a commercial boiler system if anyone is interested...)

    In the way of background info, summer temps for the heat sink are typically between 110 and 135. I do not need to keep it hotter and, as noted, the solar system is more effective at the lower temps. (In the winter, the solar heat array mostly collects snow.) My only need is for DMHW. And the genset typically does not need to run between March and September.

    As I see it, to increase my time between needing to feed the boiler, there are two options, both of which require a larger boiler (in terms of firebox, BTU output, or both).

    One relies on getting more BTUs into the heat sink, requiring that the heat sink temp be substantially raised.

    The other relies on the ability of the boiler to 'dial down' its output to keep the heat sink at 165 for a long period of time. This is what I was imagining would be possible with the Frohling and wondering if it might be possible with the Econoburn. (I understand that the Econonburn can decrease to 20% of its capacity will still maintaining gasification burn, doing this on the basis of temperature sensing.)

    Am I thinking correctly? What I don't want is a smouldering boiler making creosote. And either way, my Tarm is not up to the job. It would still take multiple firings in short succession to raise the heat sink temp sufficiently and then to keep it there for scenario one.

    I have looked at the Varmebarronen boilers, but am not convinced that they are the ticket for me. (Power is a concern, but the Frohling with 240v at 180W is only .1 amps more than my Tarm with its 120v at 80W. And I like the powered draft.)

    Re. the quip about my genset being too small, in fact it is just right. My inverters can handle a total of 3.2kW for charging the batteries, leaving 2.5kW for my house systems, which is plenty. A larger generator would suffer by not having a large enough load put to it. (Gensets need at least a 50% load to run effectively.) My overall goal is to run the genset as little as possible. But with sunrise not till after 10am and sunset before 4pm, I don't get a lot of sun in the winter for my photovoltaics!

    Am I missing anything? Very grateful for your input. Have attached a few photos to give you the lay of the land, so to speak.

    Thanks!!!!

    Attached Files:

  14. flyingcow

    flyingcow Minister of Fire

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    Love the pics. impressive set up. Doesn't look like theres a local Starbucks for miles? :)
  15. goosegunner

    goosegunner Minister of Fire

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    My Econoburn will gasify on low speed at 5 degrees under setpoint. When it drops to 10 degrees below setpoint it will go to high speed. You just gave me an idea for when it gets real cold. I will try to run extended time at low fan. It will modulate between high and low if storage is near setpoint so it might work to extend the time between fires.

    gg
  16. Dune

    Dune Minister of Fire

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    When my gensett set is finaly online it will be hooked to the grid, full load at all times.

    No batteries, just net-metering.
  17. Onfoot

    Onfoot Member

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    Reading your signature, you have quite the system! I would love to know more about your wood-fired co-generation plans. It seems pretty clear to me that wood gas should be able to fire a small turbine--so heating one's home and generating power at the same time, without needing to resort to diesel. The weak link in my system is figuring out how to provide electrical power without resorting to diesel when there is no sun or wind--but I have lots (and lots!) of wood.
  18. Onfoot

    Onfoot Member

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    A great recommendation, Cave! Tom has an impressive line of storage tanks. I am now wondering if it is worthwhile upgrading to his 1000 gallon tank, which could accommodate all of my heat exchangers pretty much as they are and would add nearly 20% more heat storage capacity. Hmmm. Another option to explore, especially as my current tank approaches the end of its useful life... Thanks!

    Barrett
  19. Dune

    Dune Minister of Fire

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    A wood gas turbine is the golden grail. I think I have the theory worked out, but I can't put my work life on hold for long enough at this point
    to model it. Dean Kammen isn't returning my calls, so it might be a while.

    In the mean time, a wood gas producer, fueling an internal combustion gensett seems to be the path of least resistance

    http://victorygasifier.com/

    Of course, being a mad scientist, I have to build mine myself. Nothing new though, the technology is well over a hundred years old at this point, and my father used one during WWII to power his fishing vessel in Norway.
  20. pybyr

    pybyr Minister of Fire

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    What about plumbing the genset with a couple of side-leg tees on both of its coolant lines (as one would do to create a secondary loop off of a primary-secondary layout) and a circulator to a dedicated "dump zone" where the genset could direct excess heat if the storage is above 180?
  21. Clarkbug

    Clarkbug Minister of Fire

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    I know this is going OT, but you could use a Lister diesel (or a Listeroid, made new in India these days) engine and put a generator head on it. They will burn on diesel, waste oil, veggie, biodiesel, and of course wood gas. Rebuild time is somewhere around 50,000 hours, completely non-electric unless you add a starter to it.

    Lots of cool vids of them on youtube.
  22. salecker

    salecker Feeling the Heat

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    Onfoot
    Hi fellow Yukoner here.
    Love the pic's of your system.I'm a newbe when it comes to the boiler.About 3 months on our Econoburn 200,and am working little things out.
    I built 1000 gal storage out of two propane tanks,and have access to more if you would be interested in any.
    When i first bought the boiler,wasn't sure if i would have the boiler building finished,or the storage,was told at the time that the 200 could be run at 1/2 output by closing one of the primarys.But i finished the building and storage,so i never tried it that way.
    The two tanks use up a space that is about 5' wide,12' deep and 10' high.I welded them to a frame and had them sprayfoamed.I can also get the propane pigs,which are about 250 gal.I'm thinking of some of these in my basement for additional storage once the rest of our house is finished and we move upstairs.
    Is the red hat your wearing a Ranger Hat ?
    Supposed to rain here tonight.
    Take Care
    Thomas
  23. Onfoot

    Onfoot Member

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    Hey Thomas--where are you located in Yukon? We are technically in Whitehorse city limits, but on the 'bush side' of the river. Appreciate learning about your propane tank storage solution. I suspect the best solution for my situation (when my current heat sink bladder needs replacing) is to build a larger tank enclosure fitted with one of Tom from Maine's liners. That would allow me to use all my heat exchange loops (quite an investment in copper there!) has well as having access to 'fiddle' with heat exchange options.

    Re. my red hat--not a Ranger hat. Just a lined wool hat with ear flaps that I inherited it from my father-in-law some years ago. It is rather ancient, the kind that loggers used to wear before hard hats.

    Weird weather, eh? But saves on wood... :)

    Cheers!

    Barrett
  24. Dune

    Dune Minister of Fire

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    You could, but I wouldn't for one main reason.
    A water cooled generator engine can readily boil water. An air cooled engine can't.

    Adding a genset and a heat exchanger to an existing hydronicly heated house creates a very effective, very efficient Co-Gen system, if sized properly and net-metering is available. For this reason alone air cooled engines are not ideal.
  25. salecker

    salecker Feeling the Heat

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    Hi Barrett
    I'm in Haines Jct.
    Yea i'd be looking to keep using the copper as well,i like to get my money's worth out of anything i spend my hard earned $$$ on.
    My next project after our house is finished is to look into wind generator's,and some solar panals for summer hot water.
    If your in the Haines Jct area,let me know if you'd like to see the Econoburn in action.
    Thomas

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