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Thread: Workshop Heater

  1. #16
    Join Date
    May 2019
    Location
    On the Continental Divide somewhere in Montana
    Posts
    102
    I run both a small woodstove and a 75K BTU sealed combustion chamber propane unit. I keep the thermostat on the propane unit at 45 degrees and fire up the woodstove when I go out to the shop each morning. We've been having a week or so of temps in the minus teens to minus 20's so the temp differential between outside and inside is quite large. Shop size is 30x30. Log walls and I insulated the attic to R-40.

  2. #17
    Thank you all very much for the advice! It's greatly appreciated. My shop is build inside of an existing barn. It is a quonset barn, so two of the walls are curved. As the barn was an existing structure, I didn't have the opportunity to install any kind of an air barrier on the exterior of the barn. I have thought about having it spray-foam insulated as this would provide the best air barrier, but wasn't able to afford it at the time. Currently, the walls and ceiling are insulated with r13 faced insulation and are covered (or being covered) with 7/16" OSB. The ends are covered in 3/16" underlayment board to accommodate the curved walls, however I'm considering redoing this with tongue and groove, or half-lap so it stops warping.

    From the responses I've read here, it seems that putting in a vented propane heater will be the best bet. I can't put in a wood stove for a couple of reasons. First is that I share the barn with my wife's horses whose stalls are in the main part of the barn. Too great a fire risk to have a woodstove in place for me to be comfortable. Second is that I am only able to work out there a few evenings per week, so I think it would probably take too long to heat the space sufficiently. I can have the propane company trench and hook up the propane line from our large propane tank for the house, so that will probably work out the best.

    Thanks again for all the advice and responses. It really helps.

  3. #18
    Join Date
    Jan 2013
    Location
    sykesville, maryland
    Posts
    861
    Quote Originally Posted by Tom Dixon View Post
    To add to my earlier post and expand on the cost of heading with my Modine Hot Dawg, I went back through the past years bills and compiled the cost and cubic footage for your reference as well as what the average temperatures are in my location, which you can find here for comparison. https://www.timeanddate.com/scripts/go.php?type=climate

    It turns out that since I have a separate meter on my shop I pay a minimum charge of $17.60 per month even if my gas usage is zero. My average cost even with that extra cost was $23.75 per month for the past 12 months and for the actual 9 months where any gas was used my average cost was $25.79 per month and I averaged 2111 Cubic feet per month. Since a gallon of propane = 35.97 cubic feet you can translate the propane cost for 2111 average cubic feet into 58.7 gallons per month and at the rate of $1.599/gallon that would be $93.86 or almost 4 times what I'm paying for natural gas. That surprised me.

    Attachment 451891


    COMPRESSED PROPANE (GASEOUS FORM) EQUIVALENCY INFORMATION: At 14.73 lbs. of pressure per square inch (psi) and 60 degrees Fahrenheit:


    • 1 cubic foot propane = 0.0278 gallons propane
    • 100 cubic feet propane = 2.78 gallons propane
    • 1 gallon propane = 35.97 cubic feet propane
    • 100 gallons propane = 3597 cubic feet propane

    "NATURAL GAS" means naturally occurring mixtures of hydrocarbon gases and vapors consisting principally of methane, whether in gaseous or liquid form.
    NATURAL GAS (GASEOUS FORM) EQUIVALENCY INFORMATION: At 14.73 lbs. of pressure per square inch (psi) and 60 degrees Fahrenheit:

    • 1 cubic foot natural gas = 0.012 gallons natural gas
    • 100 cubic feet natural gas = 1.2 gallons natural gas
    • 1 gallon natural gas = 82.62 cubic feet natural gas
    • 100 gallons natural gas = 8262 cubic feet natural gas
    I'm not surprised at the cost difference And propane yields less btus/cubic foot. It's expensive, but often the only option for gas. Even so, I'd still go propane over electric unless it's a heat pump. The advantage of the heat pump is you also get AC for the summer.

  4. #19
    You can buy an outside woodburning furnace. I built a small steel building, and installed a wood furnace, then ran ducts for supply and return to the shop, as I did not want to have a fire in my wood shop. Have to build a fire a little while before using the shop, as it takes a little while for the furnace to get hot and start blowing air. Not long after I built my setup, a local store started selling the outside wood burners.

  5. #20
    Join Date
    Jan 2012
    Location
    Olympia, WA 98502
    Posts
    13
    Has anyone used infrared heaters? I have a 3 car garage, which looks like a 2 car garage, but half of it goes back double deep. I get the double deep part, and the long wall (wife/ boss) insists on parking a car in the garage) and I have been leaning towards something like this https://www.northerntool.com/shop/to...5094_200665094 as spend most of my time in the double deep section working on the workbench, or making fancy firewood on the lathe. My friend recently put in a natural gas infrared heater and loves it, but where I could mount that in my garage would be facing away from where I spend most of my time working, and I am afraid that if it isn't line of sight, it won't make a difference for me. Bonus points to anyone else who has funky shaped workshops that found heating solutions.

  6. #21
    "My average cost even with that extra cost was $23.75 per month for the past 12 months and for the actual 9 months where any gas was used my average cost was $25.79 per month and I averaged 2111 Cubic feet per month. Since a gallon of propane = 35.97 cubic feet you can translate the propane cost for 2111 average cubic feet into 58.7 gallons per month and at the rate of $1.599/gallon that would be $93.86 or almost 4 times what I'm paying for natural gas. That surprised me."

    Tom,
    To compare NG to propane you have to convert them both to BTU's.

    One CuFt of NG = 1037 BTU's
    One gallon of propane = 91,500 BTU's

    So for 2111 CuFt of NG I get 2,189,107 BTU's or 23.92 gallons of propane. 23.92 x $1.599 = $38.26. A premium, but not outrageous.

    I'd go for the HotDawg or a Reznor. Don't forget to derate the equipment output for propane if you go that route.

    Resistance electric, over time, is usually the most expensive option. Even though it's as close to 100% efficient as you can get.

  7. #22
    Join Date
    Sep 2013
    Location
    Wayland, MA
    Posts
    3,655
    Quote Originally Posted by Stan Coryell View Post
    "
    Resistance electric, over time, is usually the most expensive option. Even though it's as close to 100% efficient as you can get.
    Heat pumps are much more efficient than resistance heaters, providing about 3X more BTUs of heat than they consume in electricity. They are using the electricity to move the heat from one place to another not generate heat directly, a much more efficient process.

  8. #23
    Quote Originally Posted by roger wiegand View Post
    Heat pumps are much more efficient than resistance heaters, providing about 3X more BTUs of heat than they consume in electricity. They are using the electricity to move the heat from one place to another not generate heat directly, a much more efficient process.
    Roger,
    You are absolutely correct.

    The point I was trying to make is that "efficiency" and energy usage are independent of each other. A 80% gas furnace allows 20% of the heat energy to escape in flue gas. An electric resistance heater converts 100% of electricity to heat. Just because the resistance heater is more "efficient" doesn't mean if is cheaper to run.

    Unless the OP wants air conditioning, I doubt the heat pump makes sense. For his region, the heat pump should be upsized to compensate for the low ambient temperature. Mitsubishi claims to be able to run as low as 20 degrees without out upsizing (I'm sceptical). Also, the recovery time is going to be much longer, so the shop should be kept close to the desired temperature. This may not save electricity costs. I would also expect the upfront installation and equipment cost to be double.

  9. #24
    Join Date
    Jan 2020
    Location
    Elizabethtown, PA
    Posts
    124
    sealed propane would be my choice, electric is expensive. Heat pumps should not even be considered unless you live in the south, they are not efficient and not ment for northern temperatures. I would also suggest more (better) insulation and to keep your shop at a lower constant temp rather than larger swings which make the heater run harder to over come the huge temp increase. Over all this will be cheaper.

  10. #25
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
    Posts
    65,675
    Quote Originally Posted by Ryan Yeaglin View Post
    Heat pumps should not even be considered unless you live in the south, they are not efficient and not ment for northern temperatures.
    Keep in mind that MiniSplits are heat pumps and they are extremely efficient, even in our area. Mine has barely blipped our electric bill over the past two years and it's either heating or cooling. My shop is rarely un-conditioned. My particular unit is good to -5ºF and units are available that do better than that. My summer efficiency is 20 SEER which is easily exceeded by multiple units on the market.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #26
    Join Date
    Feb 2010
    Location
    Collegeville PA (30 min west of Philly)
    Posts
    1,143
    Blog Entries
    1
    +1 on Jim’s comments. My HVAC professional explained that the technology has improved over the years but that the original “won’t work in the north” stigma remains
    - Bob R.
    Collegeville PA (30 minutes west of Philly)

  12. #27
    Join Date
    Sep 2013
    Location
    Wayland, MA
    Posts
    3,655
    Current ordinary commercial heat pumps will perform with a COP (Coefficient of performance) >2 at 10 degrees below zero F (-23.3 C). (COP is, is, if I understand, a comparison to electric resistance heating. So a COP of 2 generated twice as much heat as the same number of kWH put into resistance heating. At more moderate temperatures that number goes up to the 3.5-4 range. So efficiency drops, but it's not like you're going to freeze with a properly designed system. Variable speed compressors like they're using on modern AC units allow the output to be adjustable to compensate for the outside temperature.

    Here's a fairly comprehensive study: https://neea.org/img/documents/CSA-E...ing-Report.pdf

    In Massachusetts we see ten below one or two nights every 2-3 years. As a practical issue many new installs here and in the rest of New England are heat pumps and they seem to be working just fine, as long as the power stays on-- but that's another issue, and one shared with gas or oil.

    It's time to put the "heat pumps don't work in cold weather" canard to rest.

  13. #28
    Join Date
    Feb 2018
    Location
    N CA
    Posts
    1,279
    There are the old single stage hp’s and there are the mini-split HP’s. The technology has changed dramatically due to the introduction of the Japanese and Korean 410a and inverter units. As the Fujitsu rep in the six New England States if a contractor called me prior to ‘06, when we sold the single stage R22 units, and said he was going to install a HP I would ask him, “what are you nuts?” In about ‘06 we introduced the inverter 410a’s and if the same contractor called and said he wasn’t going to install a heat pump I would call him back and say, “what are you, nuts?” It was a profound improvement in performance and technology. Mini-splits maintain significant edges in operating efficiency over the typical American central HP systems. Disappointing, but the US manuf saw this coming and just fought it regulation wise making minimal investments in research and technology. Over the past 15 yrs they have had to come around or get over run, which in many cases has happened.
    ANy time you compare HP’s you have to be careful in general efficiency/temp ratings. Understand the difference. I frequently see central units and mini-splits being compared in the same threads here and on other sites. They are not the same.
    Roger make perhaps the best point. Heating systems are designed and equipment chosen based upon the lowest temp you are likely to see, “design condition.” the 25 yrs I lived in MA there were times where it would hit deep minus temps and sometimes, once in a blue moon, it would stay down there, but typically you see design condition about 2% of the seasonal heating hours, and yet that is what we pick the equipment on. This is compounded when an owner or contractor want to make sure that they have enough so rather than the correct 50kbtu unit they put in a 75 or 100...all day, every day.
    I know the central HP’s are improving in performance, but I think it has to be a really large building to benefit from a central system over a mini-split

  14. #29
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
    Posts
    65,675
    Thanks for those observations, Jack.

    As an aside, in our current future real estate considerations, one of the first things that crosses my mind when I see a property that has oil heat is "well, I can replace that with a mini-split or three."
    --

    The most expensive tool is the one you buy "cheaply" and often...

  15. I'm in MN (a little colder that OH!), and in my 20'x30' shop I run a sealed-combustion natural gas overhead heater. It works great. I keep the shop at 50 when I'm not in it, takes less than 5 minutes to warm it up to 65 when I want to do some work. Didn't really notice the change in cost - my gas bill jumps around so much it's hard to do a valid apples-to-apples comparison. For intermittent use, and when you don't plan a day ahead for "shop time", I think a gas forced-air unit is the best way to get a lot of heat out in short amount of time.

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