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What would you do?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Jimxt88, Feb 19, 2008.

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  1. Jimxt88

    Jimxt88 New Member

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    Here's my situation. Two family home in Central Maine. Approximately 5,000 sq ft., 2,500 per floor. Two chimney's, one unused the other used by an oil fired tankless boiler located in the full cellar, which is not used for living space. Two single brick unlined chimneys. The chimneys are in the middle of the house and about 20' apart. The unused chimney doesn't have a flue in the basement. The flue opening inside this chimney begins at the first story level of the house. The unused chimney has capacity for one six inch liner but not an eight inch liner when clearance from cumbustibles are taken into consideration. Two zones, two thermostats, baseboard radiant heat. One zone heats up stairs, where people are living and the second zone heats down stairs currently unoccupied but heated to 50 degrees to keep the pipes from freezing. The domestic hot and cold water supply is not seperated, upstair from down stairs. There is no propylene glycol in the radiant system. I believe this is called a two zone, closed, pressurized, hydronic oil-fired system. Correct me if I'm wrong. The house is attached to a two and a half story barn with a dirt floor. The cellar has a dirt floor as well.

    My goals is to heat the house independent of fossil fuels with the primary incentive of saving money. One possibility I am considering is to seperate the two floors making them thermally independent with the option of shutting one floor down completely while heating the other with wood, pellets, or other biomas. This would require buying and installing two boilers. I am also considering a water storage tank charged by a high energy short burst boiler. It may be more economical to retain the current plumbing arrangement and install one monster boiler in the barn with an underground hot water transfer storage tank that can hold a charge for 24 hours and requires less attendance. I am open to all suggestions including designer referrals.

    What do you recommend?

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  2. wdc1160

    wdc1160 New Member

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    1. Does fossil fuel independent mean "home grown" electric for the pumps too?
    2. Do a heat analysis. I have learned a ton from it. You wouldn't believe what you'll learn heatinghelp.com
    3. Do you have access to wood??
    4. Saying closed and pressurized is redundant, but no big deal.
    5. why would you need two boilers?
    6. Why is there "Monster" demand heat for 5000 ft of house?
  3. Jimxt88

    Jimxt88 New Member

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    1. I have not taken electricity into consideration. My electric bills are not what's killing me.
    2. I have not done a heat analysis, but I will.
    3. I have access to wood.

    4. Thank you for the correction: pressurized and closed is redundant. But is open and nonpressurized? Gravity? Please explain this.
    5. Two boilers would serve to make each floor independent of the other. The family living upstairs would be responsible for their own heat.
    6. One monster boiler would heat the entire house without seperating the floors. I use the word monster to describe a boiler like the Garn or other boilers I have seen that use gassification and solid logs creting an enormous output of heat in a very short time. This would only be efficient with a water storage tank to hold the otherwise dumped energy and use it to heat the house when the boiler is not breing fired.
  4. Jersey Bill

    Jersey Bill Member

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    Jim,
    you need to paint a better picture of your goals. It sounds like we are talking about an owner-occupied 2 family, and you are living on the 2nd floor. Separating the utilities to have the 1st floor tenants pay their own way is a good thing, but if you really want to heat the whole house with wood you would be better off to leave the system intact and put a wood fired boiler and a storage tank as you suggest. Probably outsite, or in your barn.
    If you really want to separate utilities, tackle that problem first, then consider alternate fuel stratagies. for you and your tenant.

    I dont think that you can do much with an unlined chimney that would take a 6" vent max. Maybe a direct vent pellet stove fireplace insert. I think they might be available with a 4" exhaust. If you have a local source for pellets and dont want to deal with cord stock, that might be an option.
  5. Jimxt88

    Jimxt88 New Member

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    Bill,

    Heating the whole house with wood is primary to having the tenants pay their own way. So, weather I seperate the plumbing or not, My main goal is to heat both parts of the house with wood, even if it means some of the heat would be used to keep the pipes in an empty apartment from freezing. If the plumbing were seperated, I could pump the downstairs with glycol and not worry about the tenants. One day, I hope to have the entire house occupied year round. Right now the tenant is upstairs and I am out of town. So it is my apartment that is unoccupied and heated at fifty degrees to keep the pipes from freezing. When I got into this I had no idea the rent, $300/mo which included heat would pay for less than half the cost to heat the house per month with oil.

    I am inclined to go with the wood fired boiler and storage tank in the cellar of the barn and leave seperating the two floors for later, if ever. Wood is plentiful and cheap here, so I'm told though I've never bought any. I had a few dead poplars felled, and split and they are stacked in the barn right now. I think you're right that the barn would be a good place for a boiler and storage tank. The cellar of the barn is accessible to a vehicle for deliveirng the boiler, parts and unsplit logs. Because the floor is dirt, I can dig a hole for a water storage tank.

    If I buy two wood pellet boilers from Harmon, put one up stairs for the tenants and one in the cellar for the first floor, I will still have to seperate the plumbing and use electric heat tapes to keep the pipes that pass through the down stairs from freezing up.

    I see you have a two hundred gallon storage tank and are upsizing to 1,200. Why is that?
  6. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I assume for longer run-time. The storage tank is like a thermal "battery." The larger the battery, the longer it takes to charge, but the longer it will run for, until the next "recharge."

    An accurate heat loss will be important to designing a system like this. Until then, do you know the output rating of the oil boiler (check the rating plate, and also check the service log to see if it mentions nozzle size, since sometimes techs change to a smaller nozzle)? It may be significantly oversized (many are), but would at least give us a ballpark idea of your heat demands...

    Evergreen Heat in Old Orchard has a pellet boiler and a wood boiler running in the shop. I'd recommend giving him a call and chatting about your needs and what you hope to get from your system. He's very good at talking people out of using wood... if he can't talk you out of it, then you're actually serious about doing this. I like that policy. He may also be able to recommend an installer in your area who can look your actual system over and give you a more accurate idea of what is involved in doing this conversion.

    Joe
  7. Jimxt88

    Jimxt88 New Member

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    I'm not at the house so can't check out the rating plate. Why would a tech change to a smaller nozzle on the boiler and how would that affect the cost of running the boiler. Likewise, would would be the affect of an oversized nozzle? I will call Evergreen and have a talk with them. There is no way of talking me into sticking with oil. It is prohibitively expensive. Thanks for the advice.
  8. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    If a boiler is very oversized, it will run inefficiently. Often, a smart tech will realize how oversized a boiler is, and (since he can't easily change the boiler) will install a smaller nozzle. Within reason, a smaller nozzle in a larger boiler will be more efficient, in terms of combustion parameters. Typically, after that, each subsequent tech will just replace the current nozzle with exactly what was in there, so the earlier tech's change usually ends up being preserved.

    It sounds like you have a potential interest in pellets, and Mark (the guy at Evergreen) can give you a good comparison of wood versus pellets versus oil.

    How many gallons of oil are you actually using per year?

    Joe
  9. Jimxt88

    Jimxt88 New Member

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    Since November 1st I have purchased 1,045 gal. of number 2 heating oil. I probably have enough oil stored to make it through the end of March. So, I'm guessing I'll average 220 gallons/mo. for the entire seven month heating season, October through the end of April. Add another 300 gallons for the rest of the year and it brings me to about 260 gallons per month per year on average for this year. Keep in mind the first floor of the house was maintained at 50 degrees all winter. If it were occupied and heated at 65 degrees, the amount of oil consumed would have been much greater. The short answer to your question: How many gallons sof oil are you actually using per year? 1,345, this year. Next year when both floors are occupied, probably 1,800 gallons - just a guess. At the current price of oil in my area that translates into $5,960!
  10. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Sounds like you could see a pretty realistic payoff with either wood or pellets. There are plenty of other reasons to get away from oil, but it's nice when it also makes good economic sense...

    Joe
  11. heaterman

    heaterman Minister of Fire

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    Regarding a heat loss calc. A real benefit of an accurate heat loss in your case will be that you can accurately determine the percentage of the total load each floor provides. Use this as a hypothetical situation; assume the total heat loss for the structure is 100,000 BTU's. The heat loss may reveal that the bottom floor represents 45% of that total and the upper floor requires the remaining 55%. You now have concrete data which will enable you to split heating costs on a very fair basis.......all other things being equal. This can help you make an intelligent decision as to whether you really need 2 separate heat sources or a single larger one.
  12. wdc1160

    wdc1160 New Member

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  13. Jimxt88

    Jimxt88 New Member

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    Thanks guys. These are impressive calculations. What is the factor for single-pane wooden double-hung windows with aluminum storms outside?/per sq. ft. I'm not sure I understand how I can better calculate heat loss the differential heat loss between the two floors in the house using room height, and width, etc. It seems the other variables are more determinitive. For instance, that one floor is vacant most of the time and heated at 50 degrees or that the tenants crank up the heat to 80 and open the windows to let in fresh air (not that they do).
  14. wdc1160

    wdc1160 New Member

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    Jim,

    goto heatinghelp.com they have software that give you a heat loss table and all the things that come with it. It is really to hard to do in your head.
    You know that is like 10 cords of wood, 15 if you start keeping the temperature at higher levels. (in a gasifier)
  15. Jersey Bill

    Jersey Bill Member

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    For 2 layers of glazing, an average number is U=0.55.

    I would not lower the temperature of the 1st floor apartment below 50. Most likely, the heat load on the 2nd floor apt was figured with the heat on below. Its not worth the risk of freezing pipes.

    Based on the ammount of energy being consumed, it seem to me that a full energy audit would be worthwile. How many degree days per year up by you Jim?
  16. Jimxt88

    Jimxt88 New Member

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    1,045 gal of oil is equal to ten cords of wood? I figure that's a ball park. I mean if I had a gasifying boiler and buffer storage, i.e. 2,000 gallon water storage tank, do you think I'd need ten cords of wood?

    What is a degree day? I mean how do you calulate that. I am in Piscataquis County, Maine.
  17. wdc1160

    wdc1160 New Member

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    Well, I think the concensus is that storage may not increase effciency (cause you to use less wood). You can check about 500 posts on this site and still be in wonderment as to whether that is true. I assume until I see a consensus that it isn't a fact.


    I think that you will find that a 100 gal of heating oil can be replaced with 1 cord-- all things being equal. Keep in mind you'll be a rookie with wet wood the first year.
    http://en.wikipedia.org/wiki/Heating_degree_day
  18. slowzuki

    slowzuki Feeling the Heat

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    The storage is two things, how often you want to have to add wood to the boiler and somewhat related to efficiency. A massively oversized boiler will like storage. Storage can let you go down a boiler size in some cases if you have enough storage but it doesn't really help efficency as much in that case.
  19. Jimxt88

    Jimxt88 New Member

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    The house is big but not that big. I mean, it's about 1,500 upstairs and 2,000 feet down for a total of (I'm guessing) 3,500 sq ft. with maybe 8 floot ceilings.
  20. Jersey Bill

    Jersey Bill Member

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    in your area, my map shows 7200-9000 heating degree days per year.
    based on your information on oil consumption, I backed into your design heat load which is 126,000 btu/hr, or 25 btu/sqft.
    Thats high, but not crazy high considering how cold it is there.


    I don't think that storage will increase efficiency by much, if at all.

    From what I can think of, any increase would be in the system efficiency because the boiler is running long, so the startup losses are minimized. Also, the boiler is working at a lower water temperature so the heat exchanger will be working better to extract more energy from the flue gas.

    This is offset by the storage losses. Nofossil claims 1 deg per day standing loss for his 880 gallon tank. Thats a loss of about 7 MBH per day, or about 1.4% per day loss.

    The real benefit from a decent size storage tank is the human factor. Without storage a wood boiler would have to be tended every 2-3 hours, at least my wood boiler. This can be a pain in the neck when its cold and its nicer to be in bed sleeping through the night.
    A storage tank would allow a normal person to come home from work, fire the boiler until bed time, then coast on the storage until morning. This is quality of life, not efficiency.
  21. Jimxt88

    Jimxt88 New Member

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    7,200-9,000 heating degree days per year in Piscataquis, Maine. With my oil consumption for this year I'm looking at 126,000 btu/hr, or 25 btu/sqft. Jersey, Bill, can you define what you mean by efficiency when you say "I don't think that storage will increase efficiency by much, if at all."? And "system efficiency", can you define that?

    I've under stand combustion efficiency to mean how efficiently did you combust the wood in the first place, i.e., what percentage of the chemical energy that's locked up in that piece of wood was released as heat energy vs went up the chimney uncombusted? That's the combustion efficiency. Transfer efficiency is what percentage of that heat that you produced is then released in to the living space? It seems from what you are telling me, correct me if I have misunderstood, is that storage won't directly improve my combustion efficiency or transfer efficiency but indirectly it could. And that will be because I will be able to have hotter, cleaner burns and store the energy I can't use during the burn time for later, via my storage tank. But it doesn't necessarily mean I'll be burnnig less wood. But of course, importantly I will have less burden of tending the fire. So storage means, cleaner emmissions, better combustion efficiency, good but probably not better transfer efficiencies, but definitely less fire tending burden.
  22. Jersey Bill

    Jersey Bill Member

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    sorry, I meant "system " efficiency, not "storage" efficiency
  23. wdc1160

    wdc1160 New Member

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    Jim, all of our deductions are great, but if you put in the work with a heatloss calc you'll likely not be disappointed.
    It is entirely possible that your system is ineffcient and so we are overestimating your needs, It would be nice to check estimates against a heat loss.
  24. Jersey Bill

    Jersey Bill Member

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    Right, a formal heat loss calculation has to be done. Then this can be compaired to the "field" measured heat loss derived from energy consumption.
    If they are close, you are OK. If not then you have to start looking for either an inaccuracy in the calculation, or, maybe a lack of insulation in the house, or a hole in the thermal envelope.
    The ammount of money spent on energy could definately justify an energy audit on the house, including an infra red scan. I would not wait until next year. Get it done while its still winter.
  25. Jimxt88

    Jimxt88 New Member

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    I found a photograph of my cellar and was able to zoom in and crop out the boiler plate. I have put $2,838.00 US into this piggy bank since November 1, 2007 and I'm never going to see that change again. Is there someone who could translate the numbers on the boiler plate? What do they suggest as to the heating needs for the house when I transfer to a wood boiler? Thank you.

    I will take your advice Bill and get it done this winter. I am not at the house now but will probably head up there today with my tape measure, ten gallons of glycol and a pipe cutter. Wish me luck. I will stick around till I hear back from someone regading his post. Any advice on pumping propylene, anticrossive glycol into the system and isolating the downstairs fixture branches would be appreciated too.

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