BTU needed for keeping garage ... usable

[MikeH]

I just want to be able to make the garage useable when I need to during the winter.

Usable means I might have to keep a jacket on, but I don't need a heavy coat, gloves, mittens, and a scarf. I dont' want to keep it at short sleeves levels for a long project at the bench while the -5 wind blows outside. That can wait until spring.

The garage is a detached, non-insulated, 1.5 car garage that leaks like crazy (so at least I don't have to worry too much about fumes). On that note, I'm assuming that some sort of kero heater is going to be my best bet. I'm open to recommendations. There's no gas line there, and the electricity is a single 15 amp circuit.

This is occasional only, it doesn't have to maintain anything, just raise it to the point where I can fix something that breaks in February without worrying about losing a finger to frostbite.

So, how much do I need? What's the minimum, or the recommended, or the overkill?

 

[Lennyzx11]

Based on my 24x24 2 story.
Vermont -5 to 10 degrees outside.
I’d look for a mobile home wall heater that vents outside. Around 80-100k.

1st year no insulation and 1st floor only I used a propane mr heater torpedo. 38000 btu. It struggled and ate propane bottles. And was loud.

Then a 80-100k stand up dyna glow heater did better. Was quiet also. Still only first floor.

Insulating the walls R13 made a huge difference. The 38k could keep the first floor at 50-60.

Currently running a big wood stove but have a 80k propane forced air furnace cobbled together mounted on the wall.
With insulation inside roof and walls, 5 degrees outside, it will stay above 60 fairly easily.


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[JRC3]

15A won't do anything as far as electric. I would say 25K might get you to a reasonable place after running for several hours beforehand to warm the slab and contents.

I knocked the edge off for a long time with this single setup. At my old garage it was a leaky 24x24 when it was real cold sometimes I knocked the cold down with my 30-50K propane torpedo while letting this tank mount run continuous to maintain as much as it could. Of course moisture will be a problem, but what are you gonna do.

A double tank mount with a smal fan behind would keep things reasonable and deliver about 8 hours or so on a 20lb tank.

 

[skulldrinker]

Torpedo heater is your only option. Ay least 50k btu. I had one when i started out. I felt like in heaven better than nothing. But now that i have gas i know how caveman that was.

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[MikeH]

Based on my 24x24 2 story.
Vermont -5 to 10 degrees outside.
I’d look for a mobile home wall heater that vents outside. Around 80-100k.

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I've never considered anything like this. I don't have propane on the property, so would be using the 5 gallon bottles: is that going to be cheaper than a kerosene torpedo? I'll look around in any case.

15A won't do anything as far as electric.

Yeah, I only mentioned the service so that people wouldn't be tempted to suggest electric, thanks for confirming though.

Torpedo heater is your only option. Ay least 50k btu. I had one when i started out. I felt like in heaven better than nothing. But now that i have gas i know how caveman that was.

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Thanks, I'll keep 50K as my bottom line.

 

[PWC Repair]

For a couple winters before my shop was built I used my buddies old shop with no heat. I brought my "Kerosun" radiant heater over and a small 10" fan. Turn the heater on high, fan on a chair pointed at the heater and my direction......nice warm air right where I was working. My buddy was really surprised how well it worked. The heater will run about 6+ hours on high and use 1 gallon of kerosene. If you're smelling a lot of fumes the wick is tarred up. When these are working correctly they don't stink except for a couple minutes right after lighting it.

https://www.walmart.com/ip/Dyna-Glo...MI-cDr0dLi7QIVTvHACh3Eyg10EAQYBSABEgI9tfD_BwE

 

[The Cobbler]

get a propane torpedo heater .adjustable from 75k to 125k would be my choice

 

[JRC3]

get a propane torpedo heater .adjustable from 75k to 125k would be my choice

For a 1.5 car garage? Yikes. LOL

 

[theoldwizard1]

20x20 uninsulated garage in SE MI.

When it is down in the single digits and the wind is blowing, it take TWO of these double burner (30,000 BTU) tank top heaters to keep the one side of the garage warm. Don't get to close to them or you will scorch your clothes.

 

[Steve W.]

Before I started building my shop, my wife was nice enough to score a kerosene torpedo at an estate sale. "Dual heat", it will burn K-1 or diesel (I use K-1 only) and has 50k and 75k BTU settings.

Before the insulation was installed, the heater would run for about 10-15 minutes, then be off for about 5, and repeat for the entire time I was out there. Got R-13 insulation in the trusses upstairs, in the floor/ceiling between the two levels and all the downstairs walls. Now, with outside temps in the 20s, I can easily maintain low 60s inside. The heater is run on the 50k setting, it will be on for about 3-5 minutes per hour. Usually uses less than 5 gallons (one tank) per week. I am happy enough with this for now. A mini-split is in the works, but won't be for another couple of years.

.

 

[The Cobbler]

.....

The garage is a detached, non-insulated, 1.5 car garage that leaks like crazy (so at least I don't have to worry too much about fumes).......

get a propane torpedo heater .adjustable from 75k to 125k would be my choice

For a 1.5 car garage? Yikes. LOL

Yup . heat it up fast, easily maintain warmth when its breezy in there

 

[HoosierBuddy]

Brings back memories. Before I built my cozy garage in 2006 I was working out of our barn.

I had a torpedo heater. I actually ran NG out there and converted the heater to run on it. Not an approved option....but it sort of worked.

Of course propane will work as well....it's just going to be super pricey. When you say 5 gallon bottles, I assume you mean 20 pound tank? It's like 20 bucks for an exchange on those and you'll likely only get about 2.5 gallons per exchange. So at $8 per gallon and 100,000 BTU's per gallon....you're looking at only getting about 3 hours and 20 minutes run time per cylinder if you use a 75,000 BTU heater. That works out to $6 an hour to heat your garage. The only thing that will keep you from breaking the bank is the tank is going to run out so often you won't have time to do any work in your garage, as you'll be running to the store 3 times a day.

No. This is just not a workable problem. You need to modify the problem by insulating the building and going with much larger tanks. Check with a propane supplier and see what options they can recommend. 100 pound cylinders maybe?

Phil

 

[JRC3]

...I assume you mean 20 pound tank? It's like 20 bucks for an exchange on those and you'll likely only get about 2.5 gallons per exchange....

Around here, I go to the local propane supplier and get mine completely filed for about $13. Also the Ace around the corner fills them for about $2 more. Recently we got a new Menards who fills them instead of an exchange like the two other Maenads in the area. I'm sure locale and local regulations may make a difference on availability of places to get refills. For me, the Ace won't touch a tank over 10 years old. The propane supplier does sort of a mini certification and will fill them for me. I have 4 or 5 tanks that I basically only use for the grill, but it's nice to always have a full tank if I do need to drag out the tank top or torpedo heater for whatever reason. I don't need it in the garage so much as I have 2 electric heaters out there.

Bottom line, check for places that refill 20# tanks to save money while getting more runtime. I would guesstimate it's about 50% difference compared to an exchange considering that the tank isn't under filled.

 

[HoosierBuddy]

Around here, I go to the local propane supplier and get mine completely filed for about $13. Also the Ace around the corner fills them for about $2 more. Recently we got a new Menards who fills them instead of an exchange like the two other Maenads in the area. I'm sure locale and local regulations may make a difference on availability of places to get refills. For me, the Ace won't touch a tank over 10 years old. The propane supplier does sort of a mini certification and will fill them for me. I have 4 or 5 tanks that I basically only use for the grill, but it's nice to always have a full tank if I do need to drag out the tank top or torpedo heater for whatever reason. I don't need it in the garage so much as I have 2 electric heaters out there.

Bottom line, check for places that refill 20# tanks to save money while getting more runtime. I would guesstimate it's about 50% difference compared to an exchange considering that the tank isn't under filled.

You may be getting a deal at $13 refill, but that's still about $5 per gallon for propane. Just to give you reference, if I convert the price I pay for natural gas in my barn to "gallons of propane equivalent" it is $0.64 per gallon...so your "deal" is almost 8 times what I'm paying for NG. You'd be better off buying in another format tank. Or...if you can run a NG line to it....you'd be WAY better off.

 

[Leaflessshadetree]

I have a 200k kerosene torpedo. In a drafty 30x40 (with insulated ceiling and some in the walls) Below 0 and windy it does OK at heating but noise and smell are both annoying.

In a 20x20 uninsulated garage with no ceiling I use propane. An 80K BTU "can" style convection heater if I'm going to be there for several hours and need the whole space warm. A tank top radiant style to heat a small spot quickly.

Seal as many gaps/leaks as you can, it will help more than a larger heater.

 

[JRC3]

You may be getting a deal at $13 refill, but that's still about $5 per gallon for propane. Just to give you reference, if I convert the price I pay for natural gas in my barn to "gallons of propane equivalent" it is $0.64 per gallon...so your "deal" is almost 8 times what I'm paying for NG. You'd be better off buying in another format tank. Or...if you can run a NG line to it....you'd be WAY better off.

Certainly. I'm lucky I have NG in the house too, probably about the same price as you. Eventually I want to run NG to the grill and unattached garage because I have a 45K HotDawg type from my old garage just sitting in the shed collecting dust.

 

[klassenl]

If you are actually serious about being out there in the cold spend some time sealing and insulating. At very minimum get some poly and staple it up everywhere to keep the wind from blowing all of the heat away ($).

 

[deter]

kerosene will do it as long as you have a ceiling.

 

[PhantomEB]

Insulate first and foremost, Ceiling especially.

Until then my neighbor now gets his 20 lb’ers filled at Costco for around 8$ CDN then runs a small oscillator fan to spread the heat around. No wonder he rather come over to my fully insulated and Natural gas heater. Mines 20* all day long even when it’s -20*c outside.

 

[Denwood]

Insulate first and foremost, Ceiling especially.

Until then my neighbor now gets his 20 lb’ers filled at Costco for around 8$ CDN then runs a small oscillator fan to spread the heat around. No wonder he rather come over to my fully insulated and Natural gas heater. Mines 20* all day long even when it’s -20*c outside.

Yep, insulate first. You may find it "usable" with no heat. My shop is 16x24 (insulated with spray foamed ceiling) and even with no heat running, it's consistently about 15-20C warmer than outside overnight. I only heat my shop when I need to using a 60K BTU hanging Reznor furnace which heats it up very quickly. For example, right now it's a brisk -20C outside, with a wind chill of -30C after a pretty major storm. The shop is sitting at about -2C.

I have an insulated roll up door (black) that does add some heat during sunning days, even if it's frigid outside. Thermal images here: https://www.garagejournal.com/forum/showthread.php?t=281764

The other advantage of insulating is that over winter, a parked car in there will retain it's heat a lot longer, adding a bit to the building itself. I have an EV parked in my shop this winter so there is no contribution there. However the batteries stay a lot warmer and therefore the car range in very cold temps is still pretty good. Charging also increases the pack temps...12 hours on charge will raise the pack temps to about 45F, even in the unheated garage with inside temps just below freezing. Again, insulation is key.

 

[TractorJeff]

Be realistic, buy a used 50k Kerosene Torpedo Heater on Craigslist to use when you NEED to be out there.

 

[steel 35]

Three maybe four 20 lb refill's a year $8.00 each. Worked for me for a few years, made it less uncomfortable and cheap as I could be, Helped that my wife almost stole it used, bought 2 tanks two swap!
I kept it close to where I was at and I never caught fire but a few times it felt close. Found the 500 watt flood light's cozy as well.

 

[Loose Nut Buster]

Caulk, seal the gaps, insulate and use a Tyvec type wrap to cover the insulation inside and eliminating most of the drafts. Ceiling is real important since heat rises more so than going through the walls
Save the $$ on the torpedo since the noise will be the real issue... been there both kerosene and propane both real loud even in a 26x36 area.
Instead get a tank top radiant 30-35k (its like having a wife that never screams at you) and have your propane shop (no hdwe or big box) make you up a hose length to suit your needs then you can move the heat to you and as mentioned earlier at least 4' away from you, a small fan if desired but suggested to do so.
I did this in my detached but bought two 100# tanks (one being a spare) that are outside, plumbed with 1/2" black pipe to the inside with shutoff both at the tank as well as inside and the hose connected to it.
One tank & a little per season for my needs in northern MI.
Believe it or not but that little heater easily keeps my insulated 26x36x10' walls at 50° running about 20-25 min p/hr once its up to temp, I usually heat to 40-45 most of the time when I do use it and shut it down completely after 3-4 hrs if I'm out there all day at 10-15° outside
When I'm finished I shut off the wall valve then with the 20# tank for support only just rotate it against the floor and coil the hose around the base keeping it nice & tidy.
The only real work is re lighting the heater each time since there is no auto start.
In my opinion this is the best option in your situation.

"Justice Just be aware that gasoline, propane or any other vapors they "ALL" lay on the floor and that goes for that wall heater as well."
Thats why they sell ceiling mount heaters for garages.
Good luck, stay warm and stay safe!

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[Outlander]

I'm using both a MrHeater torpedo and a bottle top in my uninsulated garage to keep it "useable" (ie around 0-5*c is fine for most of my small tasks). I wish I could decide how long we will stay here (it's a cottage, not primary residence) so I could fork out the money to insulate.

 

[OakAndIronStudios]

Just installed a 45,000 btu hotdawg heater with a 120 propane tank. VERY happy with the results in my 26x26 open ceiling studio. Insulated the roof and put corrugated metal on the inside.

 

[jonshonda]

I have a 25x25 garage w/ 9' ceilings, insulated walls, sheetrock on walls and ceiling. 60k BTU torpedo heater running for a 3 hrs will take the chill out, but will leave lots of moisture. Have a few 25lb tanks on hand, and you should be good to go.

 

[Jazz1]

It would pay to insulate and vapour barrier considering how much propane you going to burn trying to heat while most of the heat escapes the building.

 

[zc15]

Just installed a 45,000 btu hotdawg heater with a 120 propane tank. VERY happy with the results in my 26x26 open ceiling studio. Insulated the roof and put corrugated metal on the inside.

How do you like the hotdawg?

 

[greenskeeper]

I just want to be able to make the garage useable when I need to during the winter.

Usable means I might have to keep a jacket on, but I don't need a heavy coat, gloves, mittens, and a scarf. I dont' want to keep it at short sleeves levels for a long project at the bench while the -5 wind blows outside. That can wait until spring.

The garage is a detached, non-insulated, 1.5 car garage that leaks like crazy (so at least I don't have to worry too much about fumes). On that note, I'm assuming that some sort of kero heater is going to be my best bet. I'm open to recommendations. There's no gas line there, and the electricity is a single 15 amp circuit.

This is occasional only, it doesn't have to maintain anything, just raise it to the point where I can fix something that breaks in February without worrying about losing a finger to frostbite.

So, how much do I need? What's the minimum, or the recommended, or the overkill?

find someone selling or giving away a forced air oil furnace because they are converting to gas.

You can vent it out a window with some modification and run it off of 5 gallon cans or a 55 gallon drum.

That's what I did with my detached garage that I was heating with a wood stove. I already had a flue so it was easy to install the FREE oil furnace for heat. Works like a charm and it's an oversized by about 3x so it heats the garage quickly when I am out there working, otherwise the garage is unheated.

 

[OakAndIronStudios]

How do you like the hotdawg?

Love it. Have only used 40 gal of propane in two months set at 62* during the day 56* at night here in the NE PA.

 

[sparky 1971]

I have a similar garage situation in a similar climate. 30X40, but the part I use is walled off to 20X30. Uninsulated concrete block building. It does have a 9' drywall ceiling but no insulation. I use a 80,000 btu kerosene end shot heater from Menards. It does a decent job of making the shop usable. When I am out there, I set the stat at 60. The problem is that everything out there is cold, so it only shuts off for 5-10 minutes at a time. I also have a 210,000 btu kerosene heater. It works great, but it's too big for my shop. Way too loud, heats it up too quick and it almost starts raining inside, and the fumes are incredible even for my drafty building. I bought that one for a 50X100 building I was working on with plans to use it at home. It just sits waiting for my next winter pole barn project.