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Help heating garage

Post in 'DIY and General non-hearth advice' started by ArsenalDon, Jan 13, 2013.

  1. Seasoned Oak

    Seasoned Oak Minister of Fire

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    I use all these things in my work. Im rehabbing an old apartment building right now and it currently does NOT have a heating system. I have a wood stove in one aptmt and i use portable propane tank top heaters in the other one. I also have a salamander/torpedo type propane but its loud and i dont use it much. Used to use kerosene heaters but i feel the propane is Cheaper,Cleaner burning,quieter, and smells a whole lot better. Usually i do houses so a wood stove provides all the heat i need in those cases.

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  2. Highbeam

    Highbeam Minister of Fire

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    You've got to use this tool. I've really changed a lot of minds about elctric heat vs. the other options. People have it beat into their heads that electricicty is a more expensive way to heat when really it is often the cheapest plus it has several advantages over burning fossil fuels in your shop such as no open flame, no poison gas, no exhaust plumbing, cheap, and an endless supply already piped into the building.

    http://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/
  3. Seasoned Oak

    Seasoned Oak Minister of Fire

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    Great calculator. About the same results as other ones. I use mostly coal at home and switch to wood from time to time,plus i use a lot of wood were i work rehabbing old houses were i have a wood stove. My wood is practically free and the coal i burn about $500-$600 a year.
  4. stee6043

    stee6043 Minister of Fire

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    I've read countless threads on this site and others where people will claim "you'll get condensation on your tools" and "everything ends up wet" when using ventless heaters in garages. I've experienced zero condensation anywhere but on the window. I personally don't think condensation on a window is any indication of anything in a garage. My father has a nice "proper" Modine unit in his garage and he gets the exact same window fogging I get. I'd bet an electric heater would fog the windows when you "crank it up" as well. There is a certain amount of moisture in the garage no matter what you do. Once you start heating it with any source the windows will typically, eventually, end up being the coldest thing in the garage. No different than condensation on your beer after you pull it out of the fridge. And I don't blame my beer condensation on my HVAC system.
  5. stee6043

    stee6043 Minister of Fire

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    They are illegale in California...this is true. That makes me happier to have one up here in the substantially more free state of Michigan, actually.
  6. begreen

    begreen Mooderator Staff Member

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    Agreed. It is a lot cleaner too. I get headaches pretty quickly in a building that's heated by a torpedo heater and the moisture coming off of a ventless propane heater is something you don't want in a garage. It condenses easily on the ceiling insulation and inside walls if the place is not well insulated. Sooner or later that can lead to a serious mold issue.

    Instead of trying to heat the whole building, I built a shop area within the garage. I keep the shop at 50F using electric. It stops tools from rusting and is comfortable enough that I can go right into a project instead of trying to get the place warm for the first hour. It's insulated well enough that I could warm it up and ferment and age beer/wine out there too. When I have a big or dirty project I take that out into the garage after moving out the car.
  7. stee6043

    stee6043 Minister of Fire

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    I do hate to disagree with anybody having more than 10 times my number of posts...but I just don't buy the moisture issue on ventless heaters in a standard garage. And I use one nearly every other weekend in my garage.

    For every cubic meter of natural gas (methane) we burn "ventless" we put just over 3lbs of water into the air through combustion. Or we say that for every 100,000 btu's of output you would get something closer to 9lbs of water. Let's call it a gallon for nice round numbers.

    So for a "decent size" three stall garage of 825 square feet let's assume a nice average heat load, in the dead of winter, of 20,000 btu/hr to keep it at a cozy 75 degrees while working. In this case we'd have to be heating the garage for 5 hours to put a gallon of water into the air, approximately.

    Further, let's say the above mentioned garage has an unheated relative humidity in the dead of winter of 80-85% if it holds at 55 degrees F. Dim's on this garage are 25x33 with 10' ceilings. This garage holds 8,250 cubic feet of air. In an unheated state it holds about a half gallon of water in the above referenced temp/RH. In this case, assuming 20,000 btu heat requirement, we'd be adding roughly 0.2 gallons of water each hour we run the heater. Does this represent a 40% increase in "humidity" every hour we're running the heater (.5 gallons to .7 gallons)? Not even close. At 75 degrees air holds more than twice as much water as it does at 55 degrees.

    If we add 0.2 gallons but we also raise the temp to 75 degrees we end up with an increase in relative humidy of 2% or 3%. How many hours can we continue this without exceeding the water capacity of the air and we end up with "condensation all over the place"? Anecdotally I can tell you I've run mine all day long (10+ hours) more than once without having any condensation on the ceilings, walls, tools or anywhere other than my cheapo garage window. I'm really not willing to do the math required to find a real answer for "how long can you go" but I suspect there certainly is a real limit at some point. Can you realistically reach that limit in a garage that leaks air all over the place (garage doors, attic, etc)? I have no idea.

    I guess you could argue that condensation is more of a concern when the garage cools after you shut off the heater. This is when the excess moisture will want to leave the air. But garages leak air, we park wet cars in them all the time, etc and so on. I don't believe ventless heaters will cause any more of a moisture issue than parking a car packed with snow in the undercarriage inside, or washing a car for that matter. I don't know many people who park their cars outside in the winter to keep the snow from melting in the garage for fear of mold on the ceiling...

    My two cents only....or three cents I suppose.
  8. woodgeek

    woodgeek Minister of Fire

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    Remember that if you are using a heat pump or minisplit, you should put in a number >100% for the eff. Actually its COP*100%. When I put in my number (225%) I find I can make a BTU cheaper than CSD wood in the stove. And I thus become a WE/evening/recreational burner.
  9. Highbeam

    Highbeam Minister of Fire

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    I
    Absolutely. Though the minisplits are not a good candidate for a dusty woodshop since the inside unit can get gunked up easily in that environment. In house heating though, a minisplit along with cheap electric rates can totally kill everything else.

    If only there were minisplits made for heating water. I have a garage with radiant heat tubing in the slab that would love to be heated by something like a Fujitsu 15rls but they seem to spend R&D dollars on air heating and not water heating. Heck, the domestic water heaters in our homes could be replaced by this minisplit technology. It just kills me. Like small diesel engines in cars, there is technology out there that can reduce costs as well as fuel consumption but something is holding us back.
  10. woodgeek

    woodgeek Minister of Fire

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    Agreed. It comes down to ROI. For a shop used all the time (in the right clmate), a mini might make sense, for a garage you might want to heat a few hours a week, too much up front and too slow to come up to temp on demand.

    Are you sure about the gunking up the coil....is cleaning the coil on a mini a DIY-able procedure?? I haven't cleaned the coil in my split HP in 4.5 years, but I keep meaning to!
  11. FanMan

    FanMan Feeling the Heat

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    But isn't everything illegal in California, unless it's compulsory? The state that puts warning labels on ordinary untreated lumber ("this product contains a chemical known to the State of California to cause cancer")...

    Just kidding (except about the warning label, which is true)... I looked at unvented heaters a year ago and concluded I didn't want one in my house.


    Probably not a solution for the original poster, but I acquired an old oil furnace when a friend put a new one in his house (the furnace worked but the DWH coil was shot, but that didn't matter to me). Put it in my garage, fed by a 55 gallon drum, and plumbed it to a car radiator with a fan blowing through it. The water is mixed with antifreeze since I don't use it all the time. Overkill to be sure, but I can go from 0°F to comfortable in a half hour. :)

    As I'm converting my house from oil to propane, I'll replace it with another used gas furnace I recently acquired (this one was replaced because the matching air conditioner failed, but the furnace part still worked) when the oil tank runs out.
  12. Seasoned Oak

    Seasoned Oak Minister of Fire

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    You do get a lot of moisture from unvented propane heaters in a tight setting . My sister had to get rid of hers as the house was filling with mold from it. She switched to electric and the problem went away.
  13. ArsenalDon

    ArsenalDon Minister of Fire

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    Tell me about it...I paid for my own 30 years ago and now for my 30th anniversary..I get to pay for my daughters!
    Swedishchef likes this.
  14. Swedishchef

    Swedishchef Minister of Fire

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    lolol.
  15. begreen

    begreen Mooderator Staff Member

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    I think there are. I was on Mitsubishi's website a few days ago and I think I saw this. http://www.esmagazine.com/articles/...xchangers-mitsubishi-electric-cooling-heating

    They are very popular in Europe. I see multiple mfg. selling them there but not in the US.

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