# Furnace sizing for a garage



## Mvlawn (Jul 13, 2014)

Hello All

     I was sent here by havasu on Garageretreat. My new garage is a 40'X26' with 10' ceilings. It will be insulated with fiberglass in 2x4 walls and ceiling. 2 16'X8' garage doors r7.3 value and 6 windows 36"X36" and 1 man door. Cement floor


     How many BTU's would it take to heat this in North Eastern Ohio? I will be using shelled corn as my primary heat "thats what i heat my house with" and a heat pump for spring and fall.

Thanks Vern


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## nealtw (Jul 14, 2014)

Welcome to the site.
Untill the pros show up with some answers, you may find this interesting reading.
http://www.wikihow.com/Calculate-BTU-Per-Square-Foot


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## havasu (Jul 14, 2014)

Hey buddy. Glad to see you here. These guys are sharp, and I'm sure they will give you the answers needed soon!


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## bud16415 (Jul 14, 2014)

My thoughts on heating a garage up in this climate. I once put a good size wood stove I got for free in my 24x30 garage being tired of going out in the winter to work and freezing. What I soon found is if I went out at 7:00 in the morning and fired the stove it took till noon before I could even take my coat off and by 3:00 in the afternoon it was really nice to work in. if your garage is to not be heated full time the thermal mass of the floors and everything in that garage will kill you with trying to heat it up. In a house we get it warm and keep it warm so all the heater needs to do maintain the level. Another problem I had with heating my garage up over a day and then have it cool off again over the night was with condensation as it cooled and rusting my tools and equipment. 

My friend heats his garage all winter and has in floor heat and that without a doubt is best that thermal mass allows us to open the door and bring a car in and the temp drops fast with the warm air loss. Once the door is shut it warms up instantly and snow melting evaporates as soon as it hits the floors almost. Anyone building new should spend the money on putting the pex in the floors even if they don&#8217;t hook it up for a while. 

The reason you see such oversized gas units is to blow a lot of hot air fast is to try and heat the air up before the building can soak it up. 

At the house I just bought there is an unheated garage that&#8217;s about the size of yours and here is what I&#8217;m in the process of doing now. There is one smaller area with lower ceiling and I put in a dividing wall and a large extra wide door that room is about 12x16 and I&#8217;m calling that the tool room. There I&#8217;m having work bench and tool storage good lighting and some of the smaller machines. That room I&#8217;m pouring the insulation to it will have heat and even a window AC along with a smaller man door to the outside. In the cold months I can do a lot of projects in there and heat it all winter if I want turning it down to 50 when not in use. If I do have to work in the big part of the garage I can fire up a large space heater to just blow some hot air my way. And when I get to where the small room suits the work go in there and do it or just go in and get warm. 

The heating system depends a lot on how you use your garage and what works for me might not be right for you. 

Welcome to the forum Vern. Do you grow and dry your own corn? Many are going away from corn as the prices are going up. I don&#8217;t know a lot about corn burning but know quite a few with pellet stoves and they seem to be the slow and steady heat source not well suited to getting a large area hot fast. 
What type of work will you be doing in your garage? And how many hours per day will you be out there? Open flames might not be a good idea with painting and other fumes also.


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## Wuzzat? (Jul 14, 2014)

There should be a Manual J calculator online for $50.

"The energy content of shelled corn is not a constant value because of biological variability and management factors. Generally, the energy content of corn is in the range of 8,000 to 8,500 BTUs per pound of dry matter."
so corn that is not bone dry will give you less BTU than a scale will lead you to believe.  By comparison, propane is ~22K BTU/lb.

Other things being equal, if propane is available to you, on a per pound basis, the corn/propane fuel choice decision would be a tossup if the propane costs 22/8 x what the corn costs.

This
http://www.degreedays.net/
should tell you how warm or cold your area gets.  Getting from here to your answers will take a little work.

BTW, if there is a Wikihow for doing your own medical treatment, surgery, etc.,  the doctors would be out of business. . .


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## Mvlawn (Jul 14, 2014)

Thanks Everyone for the help!!!

Bud16415 I buy my corn from my neighbor this year it was cheap but I have paid as high as $7 per bushel that was a killer but for not having gas available corn is my cheapest available fuel "calculated by AA Samules my heating contractor. 

Wuzzat you are correct on the BTU rating of corn fluctuating i burn at 11 to 13% moisture. Propane would break me. Some of my neighbors heat with propane and the cost is nearly 3 times that of corn for the same size house. Thanks for the tips and there is noway I would operate on my self as I shake to bad. LOL


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## nealtw (Jul 14, 2014)

If you can burn corn in a boiler I would go with the infloor as Bud suggested.


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## Wuzzat? (Jul 15, 2014)

Mvlawn said:


> Some of my neighbors heat with propane and the cost is nearly 3 times that of corn for the same size house.


That is a quite a difference.  What are those neighbors thinking?


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