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Heat loss software

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by chewy, Mar 29, 2013.

  1. chewy

    chewy Member

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    Hello

    I'm in the process for doing a heat loss calc on my shop and I came up with a design loss of 228000 kbtus. The heated space in my shop is 36'x50'x12'. I have a r30 in the ceiling and r19 in 3 walls and r13 in one wall. There is a 12'x12' sliding door insulated with 1.5 foam board and a insulated 9'x8' overhead door. Also a 4" thick concrete slab. It's saying I have a 205,000 kbtu loss on the slab floor. Is this correct? If so what size boiler would I need to heat this and house with a 90kbtu load?

    Ty in advance

    Erin

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  2. Bob Rohr

    Bob Rohr Minister of Fire

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    Including 1-1/2" edge insulation I come up with a 30,069 BTU/ hr load. 65 indoor, 0 degrees outdoor temperatures. Typically a well built and insulated shop, in your climate runs 15- 20 BTU/ sq. ft load.

    So a boiler with a 120,000 BTU/ hr output would cover those loads. A 40KW boiler, about 109,000 at 80% efficiency, would be close, maybe the shop drops below 65F on a few real cold days.
  3. heaterman

    heaterman Minister of Fire

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    The tough factor to deal with in a shop is air infiltration. Overhead doors are notorious for leaking air and sliders are the worst case scenario. Really tough to get a good seal on them.

    I'm going to assume that
    A: you are heating with a forced air unit of some kind.
    B: you heat your shop to usual temps of around 60-65*
    C: you are not heating with a radiant floor system seeing that you do not mention tubing or any insulation under the slab.

    If that's the case I would use a rule of thumb number of 50btu/sq.ft. so you're talking about 90-100,000. for total load in a climate such as Indiana.
  4. chewy

    chewy Member

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    Ty guys for the responses

    Heater man you are correct about forced air with a wta heat ex. So I'm looking at a minimum of a 120- 130 k boiler and probably 180k? I figured I made an error somewhere.

    Do panel rads make sense in a pole building?

    How much storage would I need for these numbers? Is there any way to calculate wood consumption targets?

    Ty
    Erin
  5. heaterman

    heaterman Minister of Fire

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    Something rated for an output in the range I suggested would be plenty unless you need to recover from a deep temperature setback or an open overhead door really quickly. Your 120-130,000 suggestion would be fine.
    If it were mine, the storage capacity would depend a lot on the type of boiler I was going to use and how well I seasoned my fuel.
    Another way to look at it would be to oversize the boiler a bit if you want to be able to charge a lot of storage quickly while still providing heat to the building.
  6. chewy

    chewy Member

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    My original thought was to buy the elite 200, but not so sure now. I wasn't going to have storage with it. I like the idea of not of not having storage bc I want to do the install myself and I think it will be easier for me. Now I'm kicking the idea around. To many choices.

    Erin

    Heaterman was your load recommendation for the shop or house and shop?
  7. BadgerBoilerMN

    BadgerBoilerMN New Member

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    "If that's the case I would use a rule of thumb number of 50btu/sq.ft. so you're talking about 90-100,000. for total load in a climate such as Indiana."

    Maybe a different line of work?

    We have designed several thousand radiant floor heating systems all over N. America. The steel building we did in Kenai Alaska a couple years ago came to 23 Buth per square foot. The are no modern steel buildings with a heat load of 50 Btuh/sq.ft. save a few car washes with doors open and that it only when they are not in full operation. The old 50 Btuh thing is one of those "Rules of Thumb" that should be cut off.

    Hire an experienced professional to perform a proper ACCA Manual 'J' heat load on dedicated radiant floor software.

    If you have a slab, tube it. If the slab is in place panel rads are an option--room by room heat load still required--and hot water fan coils if you must. Where the slab goes in without tube (sad) we often design and install a gas-fired infrared system.
  8. chewy

    chewy Member

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    Badgerboiler, Ty for the response.

    Radiant floor is out of the question bc the floor is already poured. I already have an lp powered overhead radiant heat system in there, but dont want to use it if I don't have to if I'm going to throw down 10k plus on a gasser. I haven't used my lprh for the last 3 years since I installed my wta heat exchanger. Im just trying to figure out what will be the best and most efficient for my setup.

    Right now I have forced air in both house and shop power by the "free heat machine" and it sucks!

    Erin
  9. rkusek

    rkusek Minister of Fire

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    My shop and climate is very similar to yours. You should be able to crosscheck your heatloss calcs vs. how much propane you burned with the overheat LP radiant setup in the past. I would say that figure (205k) is outrageous for the shop. Neither my shop slab or my home's basement floor is insulated underneath and I know the Slantfin software I used placed a big penalty on that which doesn't seem accurate in my situation. The basement on my 2200 sqft ranch was about the same as the main floor (~35kBTU) which I question since the walkout basement is only exposed on 2 sides and has less doors and windows. I never did a calc on my shop but it is a 30x60x14 Morton with R38 batts in ceiling, R19 in walls, 2 walkout doors, an 12x18 insulated overhead, and no windows. Opening the big door in the dead of winter quickly a couple of times a day doesn't seem to cool it off much at all. The objects in there are still ~70 or so and my comfort seems to return as soon as the door is closed. If you run a business out of yours and its 25 times a day that might be a different story. My EKO 40 (130kbtu) takes 3 loads a day during the coldest days of winter to maintain the house at 70 and shed at 65-70. Base on estimates from what members have quoted here I put that at about 50kBTU/hr (3x400,000 / 24) to heat over 6000 sqft. Slantfin seems to be a little off on that. Jebatty's figures would indicate this to be about 240lbs of wood on those cold days (1 lb of wood ~ 5000btus). If you know the approximate efficiency of your "free heat machine" and your current wood consumption you should be able to get a decent approximation of your true heat load. In general, OWB are 30% and gassers about 80-90% efficient. I think one of Jebatty's posts said gasser wood consumption is about 1/3 to 1/2 of an OWB. I'm also using water/air HX in both home and shop at this time anyway.
  10. chewy

    chewy Member

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    Ty rkusek for the response. Just doing my house using ash at 3000lb cord. I use about 3/4 of a cord a week on cold weeks. So 2250lbs x 5000= 11,250,000 btu. 11,250,000/168hrs= ~67k btu hr. what does this mean with a 30% efficiency owb?

    Erin
  11. heaterman

    heaterman Minister of Fire

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    Just the shop. Much depends on the use of it, how often the doors are open and for what length of time, night time temp setbacks and how fast you want to recover, insulation, air infiltration etc. Hence the worst case estimate.

    As Badge has so politely pointed out, 50btu/sq ft is high. The reason for that is because there are so many variables involved that are unknown and simply can't be known or discovered via the www. Such are the hazards of seeking advice over the internet.

    To illustrate what Badge is talking about as far as heat loss goes, we did a new 4800 sq ft pole structure this past winter that has a 16 ft ceiling height. We installed all the insulation and tubing in the slab and wound up needing a boiler that has an output of only 113,000 btu which figures out to just a whisker over 20btu/sq ft.
    This of course was after I interviewed the owner, reviewed the blueprints for the building, understood exactly how they would use it and then did a heat loss calc to see exactly what was needed. Plus this was with a gas fired boiler so we knew exactly what we were dealing with as opposed to wood which can vary highly from manufacturers ratings.

    I would also highly recommend you hiring a heating professional to at least do a heat loss and maybe design the system for you. If you want to do the actual installation work yourself to try and save some $$.$$ by all means do so. Once you have a good design the rest of the job is just assembly. The devil is in the details though when it comes to laying everything out. Discovering exactly what you need to do over the interwebs is dicey business at best.

    PS: if there is a commonly recurring subject on this forum, it is how much better nearly any boiler will run with storage. Don't avoid it because you are shy of the extra work involved or because you don't know how to hook it up. In most cases, running a gasser with no storage is like being married to another spouse. It can eat up a LOT of time which storage eliminates.
  12. chewy

    chewy Member

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    I greatly appreciate all the help from everyone at this forum who answers questions and gives advice. Ty everyone.

    I'm not sure there is anyone in my area that can design or install a gasser. Time for google.

    Erin
  13. heaterman

    heaterman Minister of Fire

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    In what part of the state do you live?
  14. rkusek

    rkusek Minister of Fire

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    Roughly speaking, I think that means the design load calc of your home should actually be much less than the 90kbtu that I see the software gave you in your other post. If you are talking the coldest weeks of winter (single digits or less), it seems your home heat load is more in the neighborhood of 30kbtu (maybe even less) factoring in the ~30% efficency of the wood boiler. Again, roughly speaking of course and I'm no pro either. Heaterman and some of the others do this for a living. Having a pro evaluate your demand needs and still doing the work yourself like Heaterman suggested sounds like a good option. I'm guessing IN is in the land of nearly exclusive gas fired forced air heat much like NE and finding someone that has even seen a wood boiler is probably unlikely. Maybe they could at least estimate your demand needs on your shop though. If you have some knowledge of the LP use of the gas fired overhead radiant from past years, I still think you could estimate it using that data. I did do my own install work from the boiler, piping, chimney thru polebarn roof, UG pex lines, manifolds, w/a HX, etc. and had to learn a lot along the way. Like HM mentioned previously air infiltration would play a big part and those sliding doors would be the worst. Does it get opened during the winter or just the overhead? My big overhead seems to seal very well, maybe you could "winterize" the slider if it doesn't get used. FWIW, we have several nights in March with lows in the 20's and even the teens and my shed would still be at 42-43 degrees even after not burning for several days in a row (I'm out of wood!). Insulation is the key. My shed is protected from wind very well by trees to the north and even my home to some extent. From what you have said, it does seem like your heating needs might likely be met with a mid sized gasser (40KW - 130kbtu class) but take that with a grain of salt.
  15. chewy

    chewy Member

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    I live in west central indiana.

    Erin
  16. BoilerBob

    BoilerBob Member

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    Not many "Heating Professionals" round these parts.

    Is it possible to send all "house info" to professional online, for a system design?
  17. NE WOOD BURNER

    NE WOOD BURNER Minister of Fire

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  18. chewy

    chewy Member

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