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Need help to estimate amount of pellets I'll need for this winter

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by mdphilps, Sep 8, 2006.

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  1. mdphilps

    mdphilps New Member

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    I own a 2500 sq ft house that currently runs on a forced air propane furnace. Last year I used about 700 gallons of propane to heat my house. I just installed a Harman XXV pellet stove in my basement. I'm in the process of finishing my basement and hope to have it insulated before it gets too cold out. I'm going to cut a hole in my return duct in the basement and leave my furnace fan on 24 hours to circulate the heat from the basement to the rest of the house. I'd love to totally eliminate the need for propane, but I'm realistic and understand that the furnace might need to kick on every once in a while to help keep the house at a constant temperature.

    Oh yeah, I live in Pennsburg, PA which is about an hour north of Philadelphia.

    Any idea how much pellets I'll need? I've already purchased 2 tons but I'm thinking about getting a third ton before the cold hits and the prices really go nuts.

    Thanks in advance for you help,
    Matt

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  2. webbie

    webbie Seasoned Moderator Staff Member

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    The figures go like this - this assumes you can move the heat around similar to the LP and also that the efficiencies of the stove and furnace are similar - they usually are.....


    1. 700 gallons of LP at 100,000 BTU per gallon - 70,000,000 BTU input that you used last winter.
    2. Pellets are about 8,000 BTU per pound, which is 16,000,000 per ton. (2000x8000)

    70/16=4.5

    So it would take 4.5 tons of Pellets to produce the same amount of heat in your entire home. I'd pick up that third ton if I were you.
  3. wg_bent

    wg_bent Minister of Fire

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    Craig's analysis is dead on but totally analytical. (but he does state the catch) Given that you can move the heat.

    With a stove in the basement your not likely to get the two equal. You'll have to keep the basement quite hot to get the convection currents flowing enough to get heat to the rest of the house. I'd also super insulate the basement.

    Like r30+ on the walls and R10+ on the floor.
  4. cbrodsky

    cbrodsky Member

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    Craig, this calculation is way off!

    You forgot to multiple the pellet BTU content by the 4.5X miracle factor by which wood pellets magically convert into super BTU pellets that overcome all known thermodynamic principles thus allowing you to buy only 1 ton of pellets and get just as much heat as you did with 700 gallons of propane.

    :)

    Seriously, Craig's calculation is a good way to look at it if you put the stove in your living area that you heated last year. Only concern is that you are putting it in a basement that it sounds like you just finished.

    Was that 700 gallons of propane including heating your basement last year? If not, you will actually need additional BTUs keeping the basement warm with that new square footage, which should all come from pellets. Also, to keep your upper levels at a comfortable temperature, you may well end up with the basement at a much higher temperature, and that will go through a lot of pellets. It's hard to calculate this without a lot more detail - some deep well insulated basements without windows won't need much heat at all, while if much of it is above grade with walk out or a lot of windows and poor insulation, you could dump a lot of heat into it.

    I susepct the pellet stove will easily keep your propane bills from going up with the new square footage, but may not drop them a whole lot unless you insulate the basement well and go through great lengths to get heat upstairs like keeping doors open, installing grates, etc...

    -Colin
  5. webbie

    webbie Seasoned Moderator Staff Member

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    There are two types of super pellets - one is sold by HarryBack, and this one is approx double the heat value of others.

    A new type, being developed by Hasidic Jews in NYC, are the Jewish Pellets. One weeks supply of these will burn for eight weeks! That's enough to kill Harrys Pellet sales....

    :coolgrin:

    ---------------
    As mentioned, there are two issues here - BTU for BTU, and delivery of heat to the home. If you really want to heat a house of that size from the basement, a central heater (Pellet/Corn, etc.) would be a better choice than cutting holes and turning the fan on.

    If you are stuck on a freestanding stove, then experiment the first year and see what you can do to move the heat.
  6. Roospike

    Roospike New Member

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    Heat is strange stuff. As we know heat rises but its not always that easy per house. We have a 2 story home and the wood stove is down stairs ....... The front room the wood stove is in runs say 74° then the kitchen / other half of house runs 72° and the up stairs runs 70° . Stove is in the middle of the house right next to the stairs. #2 my brothers 2 story house with the wood stove on the first floor will run 74° then the up stairs will be at 82° and his stove dont sit next to the stairs. My next door neighbor has a ranch home with a finished basement ....... With his wood stove down stairs 10' away from the stairs will have to run 90° +++ to keep the first floor at 70° . He uses 3 time as much wood to heat his house with the basement wood stove than when he had the wood stove up stairs . You'll just never know for sure until you get it installed and running on how things work out. There have been some good points posted about the figures and also with you now heating the extra basement over the past with just LP upstairs. I would guess with the information shown and with what we know that you will need at least 5 tons of pellets. Its like a wood stove and how many cords of wood........ it better to have some extra than to run out. If you run out you will #1 have to pay EXTRA $$ to get the extra stock in the winter or #2 If you run out you just wont know for sure what you will have used total and what you might need for the next year .
    Also you mentioned your "last years" propane usage . If last years usage was for a mild winter then what is the usage for a normal or really cold winter ? +++++ Its always hard to figure the first winter with a new stove ....... unless you have that bit of extra onhand the first time around.
  7. saichele

    saichele Minister of Fire

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    If you keep them relatively dry, the pellets don't go bad. I think I'd go for 4 tons. If you don;t use them you probably haven't lost anything (they probably won;t be cheaper next year). If you use them all, you'll at least have a better run (maybe 2-3 months of data) to estimate your buy for next year.

    The thing most of the calculations this far have skipped is that a pellet stove is probably more efficient at delivering heat to the living space. An LP forced air system might have an 80% eficient furnace, but the ductwork proably knocks another 10 to 50% off that.

    Steve
  8. cbrodsky

    cbrodsky Member

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    Thus the plan of running the central furnace fan full time to circulate heat may actually backfire - you may lose so much heat in doing so that it negates any benefit you might get from the less expensive pellet heat in the basement. But certianly, the stove will be great to keep your basement warm.
  9. Roospike

    Roospike New Member

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    Yeah ....................Well that "central furnace fan" idea is always a great one but it dont seem like too many people actually get them to work like one would think that would. Most of the time people say that it puts out a lot colder air than what they thought it would. I thought i had it all figured out when i put two floor vents from the first floor to the room above to let the heat from down stairs go up to the rooms i wanted extra heat , just the opposite happened and cold air falls through the open vents to the 1st floor and the extra heat still goes up the stair case.
  10. mdphilps

    mdphilps New Member

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    To give more detail....

    Last winter was our first winter in this house. So I only have heating "history" for 1 year (700 gallons of LP)

    Last winter the basement was UNfinished so required no heat.

    I'm in the process of finishing the basement now. It is framed. I just need to run electricity and then I can insulate. I'm going to insulate as much as I can. This should be done in the next couple of weeks before it starts to get cold.

    I understand that my living space has increased and so will my heating needs. That was reason #1 for getting the stove. Reason #2 was to cut down if not eliminate LP (eliminate is obviously a stretch).


    Should I not cut a hole in the return duct to try and move warm air from the stove to the rest of the house? I thought that was a good idea, but it sounds like some people have tried it and it doesn't work.

    I'll probably go out and get a third ton based on everyone's comments. But I'll hold off on a forth for now.

    Thanks,
    Matt
  11. webbie

    webbie Seasoned Moderator Staff Member

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    Cutting into the return may not be worth your while at first.

    Consider this - first is that your central heat system is designed to move 100,000 BTU/hr or more through the house. A return in the room with the stove may - if you are lucky, move 1/10 this much heat. When duct loss and air dilution are figured in, you may notice 72 degree air coming out your ducts, which will feel cold to you.

    It also may cause a negative pressure in that room - buy sucking air out of it. If you don't have outside air hooked to the stove, this could actually cause the stove to function differently. In a worst case situation (unlikely) it could suck smoke out of a stove and distribute it through the house.

    A floor register into a large area upstairs might work better. In the end, perhaps two - one will act as a return - unless you already have an open stairway. As the others say, try it and see where the heat wants to go.
  12. GVA

    GVA Minister of Fire

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    Since you only have a one year heating history you may need that extra ton.... Last winter was pretty warm here in the Northeast and I used about a ton less. My stove was actualy shutting itself off in January.
  13. jabush

    jabush Feeling the Heat

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    [/quote]

    Thus the plan of running the central furnace fan full time to circulate heat may actually backfire - you may lose so much heat in doing so that it negates any benefit you might get from the less expensive pellet heat in the basement. But certianly, the stove will be great to keep your basement warm.[/quote]

    Exactly...Roo touched on this as well. When my downstairs get too hot I flip the furnace fan on to COOL it down some.
  14. HarryBack

    HarryBack New Member

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    all Craig's anti-pellet poop aside, Id suggest you pick up four tons total......but I am very skeptical that you'll adequately heat your home of 2500 square feet with a pellet stove of an output of 50,000 btu from your basement, but it will supplement your heat. Even though Craigs gonna gag on this, I heat my home of 2000 square feet with 5 tons per year, except of course, my hot water still being oil-fired, but mine sits in my living room, not the basement. Good luck.

    As for super pellets......Before my stove, I burned 1300 gals of fuel oil per year....FACT. With the stove, I burn 300 gals/yr, plus 5 tons of pellets...also FACT. You can analyze BTU content all you want, efficiencies, etc, but the FACTS speak as they do, Craig, like it or not. Whats the average BTU content of a pound of corn, by the way, used for burning in a stove?
  15. Retired_Ted

    Retired_Ted New Member

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    This is a very good thread for me since I am also going to try and suppliment my heat pump system (electric) with a pellet stove (Accentra). I thought about running the circulating fan 24/7, but, since I've read this, that may not be a good idea. My heat pump thermostat is located in a hallway next to my pellet stove's location (family room) and I'd like to avoid allowing the entire house other than the family room to cool down - a problem I had when using the fireplace as a radiant heat source. I will be using outside air which should help the house maintain humidity. I do not have an open layout as there are walls all over the place - modifications are planned. Anyway, thanks for such a great forum - I check in every day and seem to learn something every day too.
  16. mdphilps

    mdphilps New Member

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    I was thinking about the furnace fan issue that was brought up in this thread.....

    What if I installed super-quiet bathroom exhaust fans in the basement (maybe, two) and exhausted them straight up into the first floor. This would work better then the central furnace fan....right?

    I've seen some fans that run at less then 1 sone. I could hook them each to independent switches depending on what rooms I wanted to heat upstairs.

    Any downsides besides the added noise?

    Let me know what you think.

    Matt
  17. Mike Wilson

    Mike Wilson New Member

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    Based upon the information given, I think it is safe to assume that you will need 16,487,432 pellets this heating season, assuming that your area has the same number of degree days as last year. :p

    -- Mike
  18. drizler

    drizler Minister of Fire

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    Seriously, this calculating amount needed is way over rated. You are going to need at least 3 tons to be sure so just go buy them. You can stack them about any where. I have left them sitting on the porch with a blue tarp over them for weeks of snow and rain. They just aren't that easily destroyed. Get them up off the ground and under a tarp and be happy. A dry garage floor is fine as well. Believe me whatever you have left over will be there waiting for you next year.
    You might also find that running that furnace fan constantly will jack your electric bill way up as well. I just use 1 or 2 small 10" plastic box fans to do the trick. One thing you won't want os one of those little plastic half moon fans you mount in a hall doorway up near the ceiling. I got one and ditched it quick. Cursed thing sounds like my Cessna idling. Best one found yet is a nice cheap Wallyworld $10 HAUER. Its small , soft and has rounded edges for when you trip over it and you will. Ceiling fans may help you too.
    I know this is a sacralige but here goes. Don't forget you can burn corn in a fairly high concentration is any pellet stove. 30 % to 50% easily . You might just find corn is priced locally low enough to be worth your while.
    Before you go out and buy tons of pellets make sure what you are buying is good. I never could tell any difference between them but I once bought 5 bags at Agway that were "premium" and weren't even much good for lighting the stove.
  19. mdphilps

    mdphilps New Member

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    Well my question wasn't if I'm going to get a 3rd ton. If you read the whole thread, I already said I was going to pick up a 3rd ton. My question now was about the central furnace fan.....and if I install 1 or 2 super-quiet bathroom exhaust fans in the basement and vent them straight up into the first floor.
  20. GVA

    GVA Minister of Fire

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    Before you go out and buy tons of pellets make sure what you are buying is good. I never could tell any difference between them but I once bought 5 bags at Agway that were "premium" and weren't even much good for lighting the stove.[/quote]

    Hey those wern't Valfei pellets were they....
    Yeah I had a similar experiance at an agway...
    They don't seem to have much of a clue on pellets and at the very least how to store them since most of the ones I got from them were wet... never again (unless I can't find pellets anywhere else just kidding i'll freeze first) :red:
  21. wg_bent

    wg_bent Minister of Fire

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    Sorry Mike, but in reading your posts I've come to realize that you always underestimate by a lot. I think it's much closer to 16,487,563 pellets. You really have to stop misleading these folks. :cheese: (Warren ducks!)
  22. Mike Wilson

    Mike Wilson New Member

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    Warren,

    Well, I wouldn't call it underestimating... perhaps we are talking about two similar, but different, things. I made my predictions based upon premium softwood pellets, which I am told have a higher heat content than hardwood pellets, due to all that pine oil in the pellets. Maybe that accounts for it?

    -- Mike

    PS - I can still heat my whole house for an entire season on 2 splits... you're just jealous because your Osborn uses 3 splits!
  23. elkimmeg

    elkimmeg Guest

    Residential HVAC is not like its comercial applications, meaning there are no safe guards protecting the spread of fire and smoke. In comercial applications, they are required to be tied into a smoke alarm , which will either close a fire or smoke damper and stop the transmission threw the hvac system Thus preventing rappid acceleration of its spreading. The other way is the dectors, detect the presence of fire and smoke and automatically initiate the complete system shut down.

    Both systems are designed to produce heat in a closed combustion chamber. by heating water, coils, or exchangers, then transmitting the heat. Your HVAC system is not designed for any other purpose. Believe it or not it has been engineered and should be balanced for even heat distrobution. Using it to function for a purpose it not designed for, makes it dangerous and non code compliant.

    Removing air in the imediate area of a fuel burning appliance, is also non code compliant. You just reduced the need vollume of combustion air to support proper functions of that appliance. You just increased the rish of drawing Co and Co/2 gass into the living space and supplied the expressway to distribute them threw out your home.

    Fire safety = containment. Your floors and ceilings and natural containment areas . Containment buys vital time for safe exit in a time of emergency. Believe me I have seen what smoke can do every second is valuable.
    Today codes address containment, with fire blocking. Every wire pipe and vent should be draft stopped. This is one area I check when doing the rough frame inspection, I will fail it. if not draft stopped. I know it does not take a permit to cut holes in the floor nor would one ever try to obtain one admitting they were about the violate code. The only time you would see me inspecting these holes, is after the disaster has occured.

    Getting back to the engineering aspect,supply without returns is useless. Hole fans are the supplys where are the returns?
    That means cutting even more unprotected holes in your floor.

    Please, I hope you do not live in my town, where I am the inspector. Disaster inspections is not all that exciting. I hope I never have to do one agin , it really bothers me that most could have been prevented.. Some will reply that the hole in the floor will not present as great a danger as driving a car and they are right. I presented, a very strong case that they reduce you safety in your home. Its your decision to take that risk. One other thing I would know, is your fire dept response time to your home should you need them.
  24. mdphilps

    mdphilps New Member

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    Elk,

    I appreciate your honest answers and will take what you said into account.

    Thanks!!
  25. Handyman

    Handyman New Member

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    1st off I want to say hello, newbie here...

    My father was a tin knocker, installed heating systems, duct work in residential and commercial buildings.
    My uncle used to heat his home using a wood furnace tied into the house duck system using a fan.

    Your solution is rather easy, however finding a good duct man that isn't going to **** you will be a bigger challenge.. LOL

    Personally I would tie into the main duct system using a one way damper that would open with just the pressure of the forced air and close when the fan was turned off. you will need one at the head of each heating source.
    Another words, when installed just above each heating source, it would block the air from escaping into the other furnace directing the heat through the duct system.
    This would of course be limited to the ability of the craftsman.
    I do not recalled how the return air was designed for air circulation, but a good duct man could help you there.
    The air reaching the rooms won't be hot, but it will maintain the house at a comfortable level.

    Before you blow me off... I designed and built my own home by myself as well as the HVAC system. I have a all electric home with an avg cost of $2 a day , sometimes less for a 1700 sq ft country style ranch.
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