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Quanset building unkown R value, BTU #s?

DZoro
DZoro Member Posts: 1,048
Who is good with numbers? I have a Quonset style building owner wants to be heated year round. Do not know what R is in the walls/ceiling. Anyone good with numbers? Here are some of the knowns. 140'lx45'wx20'h. 30*f outside, building lost 6* in a hour 65* to 59*. What formula do I use, is this enough information to figure a btu load at -25*?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 16,607
    The temperature loss is attractive -- but there's a problem: you don't know the mass and heat capacity of the contents, so no, sorry...

    But.

    Do you have any information on the shell of the building? Is it the straight old metal shell, or is there any interior sheathing or finish on it? The best approach is to take the wall construction and add up the R values of the components to get your total R value, and then proceed as usual.

    If it's straight metal -- no sheathing or insulation -- you're going to have a tough time getting it warm in there. I'd suggest looking into overhead gas radiant units to keep the contents warm (farmers use them all the time), and not worry about the air (or wall!) temperature.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,706
    The right way is to figure out what the construction of the building is and build your own heat transmission factors and then calculate the heat loss. It takes a little work. But it's the only way to get the right heat loss. Anything else is a guess
  • DZoro
    DZoro Member Posts: 1,048
    Thanks guys, I thought maybe a formula out there with that info. But my wag is probably going to be where I will end up with. I'm at 400,000 to 480,000. I know there was a study done from one of the universities on figuring out the R value with a infared thermometer, will have to do some digging on that info. I did it on my own home many years ago, and was amazed at how well it worked. I want to say it came from North Dakota or South Dakota. Thanks anyhow.
    Dennis
  • Jamie Hall
    Jamie Hall Member Posts: 16,607
    If it's just the shell, @Dennis -- you're low, perhaps by as much as a factor of 4. I really truly recommend overhead gas fired infrared radiant... Find someone (besides me, that is!) who is registered as an Agricultural Engineer and talk to them.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • DZoro
    DZoro Member Posts: 1,048
    There is the outside steel then approx. 10-12" and some sort of insulation material. On the inside is finished with maybe 1/4" or 1/2" wall board/press brown board?? There is some insulation value there, it is just unknown how much and value.
  • Jamie Hall
    Jamie Hall Member Posts: 16,607
    You can compute an effective R value for that, assuming you have some clue as to what the insulation is. This article gives you (among a lot of other things) R values per inch for various materials:
    https://en.wikipedia.org/wiki/R-value_(insulation)
    As sort of a rough guide, each inch of lightweight material -- that wall board, for instance -- will give you around an R of 3 (so that half inch wall board would be an R of 1.5, for instance).

    The metal outer shell has an R value of zero... and the correct R value for the radiant barrier "bubble" insulation is around that same value of 3 for every inch of thickness -- and it's usually pretty thin.

    If it were my job, I'd go exploring -- take some of that wall board off and see what really is underneath it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    CanuckerSolid_Fuel_Man
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,279
    I agree with @Jamie Hall. I have a customer with a similar Quanset. Around here they spray foam the inside of the steel with as much or little as the farmer wants to pay for. Most go for 6" minimum. My customer uses his for toy/equipment storage and keeps it as 55F all winter. No windows, just 10x10 overhead door and a 36" steel man door. Heats it with an oil fired Olsen furnace 100,000 btu. No insulation below slab.

    When foamed properly they are virtually air-tight other than overhead doors etc.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!