Heating the Shop

M

Mr. M

Joined
Jan 3, 2011
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62
So, my lovely bride and I bought a small piece of land and a shop with a house also on the property :D
I am trying to decide the best way to keep the insulated section of the shop just above freezing. The shop is 26'x72' and the insulated section is 18'x26' that I want to keep warm.
I have a woodstove in there that I use when I'm out there so it doesn't need to be able to get it real warm, just 38 degrees or so.
I don't have gas on the property but if a gas heater will be the best I can look into that.
What suggestions do you guys have?
 
Propane forge!

Better yet, Waste Oil Forge

Barring those, I'd still lean toward waste oil heat, especially if you have or can find a source for used veggie or motor oil. Plenty of easy and inexpensive plans to build a WO heater.

There are also rocket type stoves built into earthen/rock benches = large heated mass heated extremely efficiently, so efficiently that basically only water vapor is exhausted at just over room temperature.
 
An oil-filled radiator type heater is exactly what you want. Safe, and will keep the space as warm as you need. You might need 2.
 
+2 for oil filled radiator(s).

They provide warm heat and low energy consumption. They also last a long time.

Another thing that might be worth considering is some sort of solar collector that will warm the shop all day. The temp will drop overnight, but the OFH will keep it above freezing.
 
I started out with a wood burning stove, but soon took it out and put in a wall mounted propane furnace...Never looked back....The wood took to long to get heat..But lots of insulation really helps............carl
 
I don't think an oil filled heater would be sufficient in central Minnesota, where it regularly gets, what, -25° F? Oil filled heater might keep you above 0° on a -20° F night, but trying to keep a space 60° above ambient is going to require more than 110v.

Ask your neighbors, they probably already know how to do it in your part of the world.
 
I have a wood stove and use a blower system that I made from an old ceiling mounted gas drop down heater. It already had a fan and just had to do a little welding to change up the heat exchanger. Mounted it 6 inches above the stove in the flu. It will heat my insulated 20 x 40 shop when freezing outside. Here is a link to one they sell at Tractor supply. They say 10% heat re-coup. Well mine is way above that and it will make my shop nice and warm. I will even be working in short sleeves when it is a roaring fire. I cut my own wood and crap trees that burn fast are great. Yes I feed it a lot but also use oak to build a base fire. I have a steel pipe that I drilled 6 3/32" holes in and put a cap on the end of the pipe to make a burner that connects to a propane tank. On the bottom of the pipe is an angle iron welded so the flames are pointed up. Then made a 2" wide sq, (the top is open with small rebar welded on it to prevent wood falling into it and leave it in the stove. It is so I can slide the propane pipe into the stove, light it and get instant fire. When the fire is lite I just slide it out. Wait 4 or 5 minutes and turn on the fan and hot air is blowing. Close to my bench. Works great, I get my wood for free and warms my shop all winter. Dont think because I live in the south that it does not get cold here. It is a nasty cold because of the humidity. This system is cheap to run and easy to set up. This link is just to give you an idea on how to build it because I made mine much better with a throw away old gas heater. Can probably find one at a scrap yard or call some heating companies and ask for throw away,s. Main thing is it works great.
http://www.tractorsupply.com/en/store/united-states-stove-miracle-heat-6-in-heat-reclaimer
 
Buy a decent wood stove designed to handle the load for your shop and don't be afraid to pay more. A good stove will hold the warmth in overnight. The climate in Minnesota has serious winters and electric heat (those oil filled heaters) will do little but run up the electric bill in short order. They may work fine for those of you who live down south who mentioned them, but come up here in January during the freeze for a visit and you will understand why I don't recommend them. Check the insulation, add more to attic, insulation is your best friend for the type of climate in that area. Temperatures fall into the -30s sometimes for days at a time, make sure you have a good supply of seasoned firewood.
 
I did the math for a 220V electric heater vs. propane for BTU's per dollar, and propane came out slightly cheaper.

That said, I wish I'd just gone with an electric shop heater, because constantly filling propane tanks in the middle of winter is a bummer. The cost difference wasn't that much.
 
Another vote for electric Oil Filled Radiator. seems to be the most economical electric heat option. also some of the newer ones have digital thermostats, making them even more efficient. the one i got last year even has an option just for keeping the temperature above freezing to prevent frozen pipes etc. as mentioned before, perhaps get two...good luck!
 
zaph1 said:
I don't think an oil filled heater would be sufficient in central Minnesota, where it regularly gets, what, -25° F? Oil filled heater might keep you above 0° on a -20° F night, but trying to keep a space 60° above ambient is going to require more than 110v.

Ask your neighbors, they probably already know how to do it in your part of the world.
Click to expand...

We have some nights down to those temps but not a ton of them.

I was thinking about a 220v heater for a few reasons,

A. I don't have to get a tank
B. I only need it to stay at 35-40 degrees
C. It is safer that a homemade waste oil burner

I like the idea of a waste oil burner, but not for when I'm not around. I know a few heavy truck repair places that had fires due to them so I'm a little skittish.
Also I cannot spend a grand on a heater out there :D My bride was ok that the shop has more sq footage than the house, but I don't think she'd ok me spending that.
416, you said an oil filled seems to work good for you up in the tundra? What brand/size do you have?
 
Mr. M said:
We have some nights down to those temps but not a ton of them.

I was thinking about a 220v heater for a few reasons,

A. I don't have to get a tank
B. I only need it to stay at 35-40 degrees
C. It is safer that a homemade waste oil burner

I like the idea of a waste oil burner, but not for when I'm not around. I know a few heavy truck repair places that had fires due to them so I'm a little skittish.
Also I cannot spend a grand on a heater out there :D My bride was ok that the shop has more sq footage than the house, but I don't think she'd ok me spending that.
416, you said an oil filled seems to work good for you up in the tundra? What brand/size do you have?
Click to expand...

Thermal mass rocket stove
 
Even if you had to buy 3 oil filled heaters, the cost probably wouldn't be over $150. Just space them evenly. The will do exactly what you want them to do-safely.
 
Mr. M said:
We have some nights down to those temps but not a ton of them.

I was thinking about a 220v heater for a few reasons,

A. I don't have to get a tank

Also I cannot spend a grand on a heater out there
Click to expand...

Unless electricity prices are stable and lower than we pay here (ontario) expect some large bills. True an electric heater/furnace are cheap to buy and install, but operating costs are much higher than fired heaters/furnaces over time. If you are planing to move after a year or so then go electric, if you plan to be there for the long term buy a good oil or propane furnace with duct work you will not regret it. In Ontario going just by the math oil heat is about half the operating cost of standard resistance electric heat.
 
I heat my home/shop/garage with geothermal in floor radiant heat. Super expensive to set up and instal, but it pays for itself in 10 years compared to traditional systems.
 
One is a few years old Kenwood model EW0507TK. I have seen ones that look very similar in stores, but no longer Kenwood...this one has a simple old school knob for temps and a timer. Basic and solid...newer ones dont seem to be as well built...
Second one is a Bionaire BOF2001-CN. This has a digital thermostat, various options including a setting to keep just above freezing temp. Probably more efficient than the other one. Got this one last year...
Both are made in China. Approx. $60 - $70 if I recall correctly...
Also if the need arises, turn the temp high and blow a fan at them to warm up the place a little quicker :)
 
One kilowatt has 3412 BTU per hour when used in standard electric resistance space heaters or electric furnaces/baseboards. It does not matter what the shape of the heater is fan or non fan operated or whether the space heater is oil filled. If is has a standard element then 3412 BTU per kilowatt/hour is all it can produce. Many come in with a 1.5 kilowatt output for 5,200 BTU's, and when you start to add it up it becomes expensive to use these space heaters for anything more than spot heat for areas where the main heating system falls short. With that said most wood stoves output between 50,000 to 100,000 BTUs per hour, and probably more when the wood is very dry.
 
What I took from the OPs post was he was going to keep it nice and warm during the day with the wood stove, and only wanted a backup for overnight to avoid freezing temps. If he stokes the woodstove and shuts the damper at quitting time, most likely the oil filled heaters will not come on till the wee hours, if at all. They won't keep it at 60F, but should keep it above 35F.

I agree that good insulation, double glazed windows ( maybe even with insulated shutters), and sealing all cracks is your first line of defense against heat loss.







I just did some math with round numbers, and:
If the shop is well insulated it should stay warm enough with two oil filed heaters ( actually, any type of electric heater). A 1500W heater delivers about 5000 BTUs. An insulated 18X26 area is a bit under 500 sqft. It takes about25,000 BTU to heat 1000 sqft., so about 12,000 BTU to heat that size room for normal daytime temperature, and about 6000BTU to keep it easily above freezing. Giving some loss and inefficiency, two heaters will work fine and draw 3 kilowatts. That would be about 20 KWH if they run six hours a night. At $0.11/KWH in Minnesota, that would cost around two bucks a night for any night it drops below freezing. Three heaters should hold it above freezing even during sub-zero days.
 
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