# Electric garage heaters ?



## Pallet Pete (Aug 11, 2013)

I am starting to consider a ceiling mount garage heater and need some help with the math. 

The garage is 

22.8 long
23.8 wide 
15ft tall front 
10ft tall rear

Here is my first issue how do I determine the cubic ft with a slanted roof ? 

Second my electric company charges 13cpm per kwh so how would I determine the per hour charge on a 5000 watt heater. 

Here is what I am considering. 
http://www.lowes.com/pd_359041-49285-FUH54_0__?productId=3499392

Currently I use a 80,000 btu heater that burns a 20 gallon propane tank in 4-8 hours depending on how cold it is outside. Being in Michigan winters its 4 hours when below zero out. I was considering wood or pellet but I don't want to give up the floor space and the county gives you almighty heck about it too.

Thanks 
Pete


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## BrotherBart (Aug 11, 2013)

5,000 watt heater cooks off 5 kwh per hour.

Sixty-five cents an hour.


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## heat seeker (Aug 11, 2013)

Figure the volume of the roof area seperately. Draw an imaginary line across one end of the gable where the ceiling would be, if you had one. Measure, in the center, the height from the "ceiling" to the peak .Then measure the width of the gable at the bottom. Multiply the two dimensions, then divide by two. That gives the area of the gable. Multiply that number times the length of the garage. You now have the volume of your "attic".

The formula for the area of the gable: ½bh, which is ½ times the base times the height of the triangle.

http://www.ask.com/web?q=area+of+a+triangle+formula&qsrc=178&o=0&l=dir

The volume of the work area is Length times Width times Height. Add the two volumes together, and you have the total volume. You'd save a load of heat if you could install some sort of ceiling to isolate the attic area.


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## Pallet Pete (Aug 11, 2013)

At $12 for 20 pounds of propane electric is cheaper alright ! Propane is $144 a day vs $15.6 a day for electric 5000 watt. Thanks BB that is a seller. 

Now for the cubic ft.

I did it at 12 ft height because the front was 14 and the back 10. My logic is that if I where to flatten it the back would rise two feet and the front lower two. Does that even make sense lol. I came up with 6511 cubic ft.
Pete


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## heat seeker (Aug 11, 2013)

Makes sense, I didn't allow for the different heights. Assuming that the roofline is straight, you got it right.


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## Pallet Pete (Aug 11, 2013)

heat seeker said:


> Makes sense, I didn't allow for the different heights. Assuming that the roofline is straight, you got it right.



Thanks it is straight. You guys are great !

Pete


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## Pallet Pete (Aug 11, 2013)

Does anyone have experience with this style of heaters and how well they work ?

Pete


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## Grisu (Aug 11, 2013)

Be careful not to underestimate your heating load with the electric heater. 1 gallon of propane = 91,000 BTU * 20 = ~1.8 mill BTU. If the heater is 75% efficient you have a heating load of 1.35 mill BTU in 4 to 8 hrs. 1 kWh has 3,400 BTU, the max per hour you will get are therefore 3,400 * 5 = 17,000 BTU or in 4 hrs 68,000 BTU. Unless your propane heater is awfully inefficient (or I made a stupid mistake with my numbers) the system you are thinking of will not be able to get the garage space heated.

To calculate what is really cheaper for heating:
1 pound propane = $0.60 = 22,000 BTU; cost per 1000 BTU: 2.72 cent
1 kWh electricity = $0.13 = 3,400 BTU; cost per 1000 BTU: 3.82 cent

Only when the propane heater is less than 70% efficient you will save money but it will take a while to recoup the cost for such a rather large electric heater that gives you at least 250,000 BTU per hour (75,000 watt system) when it is really cold outside. Have you thought about insulating instead? Maybe just a dropped ceiling with some insulation above would help.

P.S. You could also test if a 5000 watt heater would be sufficient assuming your circuit can handle it. Borrow from friends/family 3 space heaters in the winter. Those usually use 1500 watt on high. Let them all run continuously for a while in your garage and see if they get it up to temp. If it is not even close your 5000 watt heater will be too small.


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## Ashful (Aug 12, 2013)

Pallet Pete said:


> I am starting to consider a ceiling mount garage heater and need some help with the math.
> 
> The garage is
> 
> ...


(22.8 x 23.8 x 10) + 1/2 x (22.8 x 23.8 x 5) = 5426 + 1357 = 6783 cu.ft.

I had an electric heater in my last shop, heating only 2261 cu.ft. of extremely well-insulated space (minus one overhead door).  I don't remember the numbers now, but it was painfully expensive to keep it going all winter, particularly when I was shooting paint, and had to keep temps close to 70F.  I'd usually keep it closer to 55F, though.


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## Pallet Pete (Aug 12, 2013)

Grisu said:


> Be careful not to underestimate your heating load with the electric heater. 1 gallon of propane = 91,000 BTU * 20 = ~1.8 mill BTU. If the heater is 75% efficient you have a heating load of 1.35 mill BTU in 4 to 8 hrs. 1 kWh has 3,400 BTU, the max per hour you will get are therefore 3,400 * 5 = 17,000 BTU or in 4 hrs 68,000 BTU. Unless your propane heater is awfully inefficient (or I made a stupid mistake with my numbers) the system you are thinking of will not be able to get the garage space heated.
> 
> To calculate what is really cheaper for heating:
> 1 pound propane = $0.60 = 22,000 BTU; cost per 1000 BTU: 2.72 cent
> ...



Yes I did think about insulating the ceiling but I use the rafters for storage so that's not really feasible to do right now. Thanks for all the good info I will certainly research more.

Pete


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## Pallet Pete (Aug 12, 2013)

Joful said:


> (22.8 x 23.8 x 10) + 1/2 x (22.8 x 23.8 x 5) = 5426 + 1357 = 6783 cu.ft.
> 
> I had an electric heater in my last shop, heating only 2261 cu.ft. of extremely well-insulated space (minus one overhead door).  I don't remember the numbers now, but it was painfully expensive to keep it going all winter, particularly when I was shooting paint, and had to keep temps close to 70F.  I'd usually keep it closer to 55F, though.



Joful I am not using heat all the time but instead on the weekends and possibly weeknights for a couple hours at a time. That's why propane is so painful for me lol 4 hours 20lbs ! I think I would be willing to pay the same price but with the convenience of not filling a tank every time I use the garage. ( not that I want too )

Pete


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## stee6043 (Aug 12, 2013)

Do you have natural gas?  I think you're going to find that properly heating your garage with electric is going to come with a fair bit of upfront cost. 

The heater you linked above is 240V.  Do you have 240V wired to your garage already?  If not, how far will you have to run a new line?  I assume you're going to need a 30amp 240v circuit for this rig.  Copper is expensive these days.  Ground fault 240v breakers are even more redicilous (if required).

You can't beat electric in terms of efficiency.  But for the amount of use you're talking about I think you're going to be hard pressed to beat gas/propane in bang-for-the-buck.  Maybe you could get a bigger propane bottle if you don't have natural gas available?  My two cents only.


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## Pallet Pete (Aug 12, 2013)

stee6043 said:


> Do you have natural gas?  I think you're going to find that properly heating your garage with electric is going to come with a fair bit of upfront cost.
> 
> The heater you linked above is 240V.  Do you have 240V wired to your garage already?  If not, how far will you have to run a new line?  I assume you're going to need a 30amp 240v circuit for this rig.  Copper is expensive these days.  Ground fault 240v breakers are even more redicilous (if required).
> 
> You can't beat electric in terms of efficiency.  But for the amount of use you're talking about I think you're going to be hard pressed to beat gas/propane in bang-for-the-buck.  Maybe you could get a bigger propane bottle if you don't have natural gas available?  My two cents only.



I rewired my garage over the summer with 60amp service in the garage so that shouldn't be an issue. And yes its pricey but worth it because I weld frequently. Propane is expensive a bigger tank would still be just as much as 20 pound tanks but a fill at once. Our natural gas would cost a fortune to run to the garage otherwise I would do that. They quoted us at $3200 to run it out to the garage. O well sounds like I might have to give up the idea ! 

Pete


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## Highbeam (Aug 12, 2013)

That 5000 watt heater uses 5kwh per hour so at 13 cents each the electric will be 65 cents per hour and if you run it all day it will cost you 15.6 bucks. You are only getting like 15700 btus from that per hour though.

Propane in that burner is only 80% efficient so you are getting 64000 btus per hour or 4 times as much output.

So the electric cost to get the equivalent heat would be 62.4$ per day.

Your propane cost is okay at 2.4 per gallon. Something is fishy. Burning 20#s of propane in 4 hours with an 80,000 btu burner is a bit odd. 20# gets you 440000 btus. In four hours you would have to be eating it at a rate of 110000 btus per hour. That's not 80,000.

You know what might be happening. It's not funny really, but maybe a little. Perhaps you are freezing the little BBQ size tank of propane so the output stops. This happens when you overdraw a small propane tank. Then you think it is empty but really it isn't and you go and exchange the tank for a new one.

You shouldn't be feeding an 80,000 btu burner with a BBQ tank, it is too small.


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## semipro (Aug 12, 2013)

Pete, it may be worth running the numbers on using a ductless mini-split heat pump.  
While the up front cost will be much higher, the break-even point may not be as long as you think.  
While it won't necessarily heat the garage quickly you may be able to warm up the place beforehand using a remote control or scheduled operation.


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## ScotO (Aug 12, 2013)

Hey, what the heck?!?  Put a little woodstove out there, Pete!!  just scrounge a little extra wood (or get some pine off of our buddy Dennis up there near you).  That pine gets the room warm in no time, just go out a half hour before you plan on being out there and build you a fire.....VOILLA!!

This IS a woodburning forum, remember?


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## Highbeam (Aug 12, 2013)

Scotty Overkill said:


> Hey, what the heck?!? Put a little woodstove out there, Pete!! just scrounge a little extra wood (or get some pine off of our buddy Dennis up there near you). That pine gets the room warm in no time, just go out a half hour before you plan on being out there and build you a fire.....VOILLA!!
> 
> This IS a woodburning forum, remember?


 
Trouble is that the code and most insurance companies forbid a stove in a garage or an outbuilding. Stupid rule and often ignored but in our modern society you have to be careful.


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## ScotO (Aug 12, 2013)

Highbeam said:


> Trouble is that the code and most insurance companies forbid a stove in a garage or an outbuilding. Stupid rule and often ignored but in our modern society you have to be careful.


yeah, I know....same goes with my insurance co. in regards to a stove in the garage......they won't allow it.

But I DO have one in my workshop/barn out in the backyard, and I love that stove.  It's nice to be able to go out there and work in good dry heat.....


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## Highbeam (Aug 12, 2013)

Scotty Overkill said:


> yeah, I know....same goes with my insurance co. in regards to a stove in the garage......they won't allow it.
> 
> But I DO have one in my workshop/barn out in the backyard, and I love that stove. It's nice to be able to go out there and work in good dry heat.....


 
I am jealous. My 30x60 shop may not have a solid fuel burner as it is an "outbuilding" according to state farm. I woudl love to use some wood out there.


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## ScotO (Aug 12, 2013)

Highbeam said:


> I am jealous. My 30x60 shop may not have a solid fuel burner as it is an "outbuilding" according to state farm. I woudl love to use some wood out there.


I don't think I'd even want a shop if I wasn't allowed a woodstove in it......


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## Pallet Pete (Aug 12, 2013)

Scotty Overkill said:


> Hey, what the heck?!?  Put a little woodstove out there, Pete!!  just scrounge a little extra wood (or get some pine off of our buddy Dennis up there near you).  That pine gets the room warm in no time, just go out a half hour before you plan on being out there and build you a fire.....VOILLA!!
> 
> This IS a woodburning forum, remember?



I wish ! I went through the gates of hell and back already trying to get them to allow an add on furnace in the garage 24" off the floor. It ended up that no insurance company anywhere that I called would allow it or the county for that matter. It is a nightmare to get approval for. 

My other thought is a pellet stove with an outside air kit 15" off the ground. The county will approve that as long as the insurance does. The insurance won't approve it without written consent from the county and the county won't approve it without written consent from the insurance company. What a mess ! 

Pete


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## Pallet Pete (Aug 12, 2013)

Maybe I should be looking at coal ? Pot belly stoves are cheap !

Pete


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## Highbeam (Aug 12, 2013)

For us, the prohibition was "solid fuel heater". So no coal either. I could put in a gas fireplace though.

Really, those hanging reznor type heaters really kick out the heat but without NG they cost some bucks to run.

Electric heat is very cheap and easy to install. Yes, it will take a 30 amp circuit but with 60 amps available you have plenty. Remember, your welder isn't a huge demand item. 60 amps is fine for most shops. No open flame, no ducting, no emissions, you already have an endless supply of fuel, etc. Electric has some benefits.


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## fbelec (Aug 13, 2013)

also remember that 15 and cents dollar a day is the electric heater running full blast and never shutting down. if it has a thermostat on it and is cycling on and off to maintain a temp it will be cheaper to run


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## jharkin (Aug 19, 2013)

Scotty Overkill said:


> I don't think I'd even want a shop if I wasn't allowed a woodstove in it......


 

Interesting. I had thought the woodstove prohibition was _only_ for garages on the thinking that there may be stoves gasoline or other volatile chemicals in a garage that could get ignited.  I certainly see a lot of  barns and even large shed workshops around here with stovepipes.


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## oldspark (Aug 19, 2013)

jharkin said:


> Interesting. I had thought the woodstove prohibition was _only_ for garages on the thinking that there may be stoves gasoline or other volatile chemicals in a garage that could get ignited. I certainly see a lot of barns and even large shed workshops around here with stovepipes.


 Yep does not seem to be a problem here either, do they allow you to have a welder in the shop, seems like more of an issue then a wood stove.


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## Swedishchef (Aug 19, 2013)

In the town where I live, most people have bigger garages (or shops, whatever you want to use as a name) than they do houses. My garage is not big. And it is well insulated. I bought a great heater and it takes no time to heat the place...

http://www.ouellet.com/residential-heating-specs-usa.aspx?i=56

I didnt want to lose storage space for clearance issues in my garage. PLUS it would have cost me about $600 for a stove and another $600-$700 in stove pipe, chimney, etc. That is a pile of electricity....especially at the low cost where I live.
Andrew


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## oldspark (Aug 19, 2013)

Our rates are high here, any thing electric raised the bill dramaticly.


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## Swedishchef (Aug 19, 2013)

oldspark said:


> Our rates are high here, any thing electric raised the bill dramaticly.


Average of about 7 cents /kWh here


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## Highbeam (Aug 19, 2013)

Two things. The county/city or other AHJ can prohibit the garage stove and your insurance company can prohibit a garage stove. They can also both interpret what a garage is. To you it's a shop, to them it may be a garage.

Finally, the insurance company has no duty to accomodate you. If they say no then you must choose to buy insurance elsewhere. Even if the insurance allows it, an illegal installation (if unpermitted it is deemed illegal by your AHJ) will give your insurance company the right to deny your claim.

You need both insurance AND AHJ to agree to allow it. You want protection from liability should your shop burn and somebody be hurt. Even the firefighter that dies while trying to put out your shop can ruin you financially since you are "at fault" due to your illegal installation.


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## oldspark (Aug 19, 2013)

Well I know a guy who collected insurance for a shop that burnt up and it had a wood burner in it so I just assumed it's not a problem in this area.


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## Highbeam (Aug 19, 2013)

oldspark said:


> Well I know a guy who collected insurance for a shop that burnt up and it had a wood burner in it so I just assumed it's not a problem in this area.


 
That's a chance I'd take on a 5000$ shed. It's not a chance I'd take on my home, shop, cars, or on the medical expenses of the people hurt as a result of the fire.

You'd hope that all parties involved would be able to find that something legal caused the fire but I know fire marshals and when they can't figure it out they will blame it on the stove or electrical. I bet lots of people do their own unpermitted electrical work in barns too, that's another big risk that you don't realize until it is too late.


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## oldspark (Aug 19, 2013)

Not hand cuffed by that stuff here in the middle of no where, you seem angry, not my fault things are different here in the mid west, many parts of the country I could not stand to live.
By the way I am not taking a chance on any thing but you make it sound like I am, my insurance company knows what I have.


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## oldspark (Aug 19, 2013)

"That's a chance I'd take on a 5000$ shed."
Where the hell do you get a $5000 shed, way more then that tied up in it, my SIL (who has a wood burner in his) has way more money in his then I do.


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## oldspark (Aug 19, 2013)

So high beam do yu have a wood burner in your house, I guess I dont get where you are coming from, like I said you seem angry about something.


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## Highbeam (Aug 20, 2013)

oldspark said:


> So high beam do yu have a wood burner in your house, I guess I dont get where you are coming from, like I said you seem angry about something.


 
Of course I have a stove in my house. Permitted and legal and insured. My shed does not have a stove and I am bitter about it. In my case, state farm is the insurer and a large company, they refused to allow a stove in an outbuilding. The value of the buildings is one thing but the liability you have in the injury or death of people is far larger. Even after you sell the home, the liability follows you if you leave the stove in place. 

Ever heard of ignorant bliss? If you really thought it was acceptable to have a stove in your barn then why don't you get AHJ and insurance approval in writing? You may think you have the answers but that is only because you have never asked the questions.


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## oldspark (Aug 20, 2013)

"Ever heard of ignorant bliss?"
I love the smell of condescending in the morning.
All I did was tell you some have collected insurance for a fire in a shop.
Dont have one in my shop but am going to call insurance company before I install it.
Not sure why you think your part of the world is the same as every where else, codes and regulations vary a lot from state to state.
You said you were bitter about it-no shiit.


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## Highbeam (Aug 20, 2013)

oldspark said:


> "Ever heard of ignorant bliss?"
> I love the smell of condescending in the morning.
> All I did was tell you some have collected insurance for a fire in a shop.
> Dont have one in my shop but am going to call insurance company before I install it.
> ...


 
Dude, you shot three rapid fire posts at me and then gripe that I responded?

I'm bitter but knowledgable due to my experience on this. We're talking about national fire codes and national insurance companies, your location is not that special.


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## Swedishchef (Aug 20, 2013)

What ever happened to the talk about electric garage heaters?!


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## oldspark (Aug 20, 2013)

3 posts because I did not take the time to put it into one, I did not gripe cause you responded, did you read my post, you seem to think I dont have a clue and stated as such, they collected insurance on  a fire in a shop so where the hell was the fire marshal in that?


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## oldspark (Aug 20, 2013)

Swedishchef said:


> What ever happened to the talk about electric garage heaters?!


 What electric heaters?


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## oldspark (Aug 20, 2013)

Just got off the phone with my insurance company, THEY have no problem with it what so ever and no raise in price.


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## Ashful (Aug 20, 2013)

(crickets...)


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## Pallet Pete (Aug 20, 2013)

Joful said:


> (crickets...)


What happened while I was away ? Wow. So here is the thing guys solid fuel is banned in my county for a garage my style. I just had the inspector and fire marshall out for an inspection. It's a no go unfortunately. I can only install natural gas or electric heat. Looks like I will finish insulating the doors and install an electric heater probably a 7500 watt. 

Pete


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## Highbeam (Aug 20, 2013)

Pallet Pete said:


> It's a no go unfortunately.
> Pete


 
At least you asked and know the real answer before spending money.

7500 watts is  decent heater. 240 volts means it is a 31.25 amp appliance and that means you need a 40 amp circuit. 8 gauge romex will do it. This will be similar to an oven circuit in your house.


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## Swedishchef (Aug 24, 2013)

Did ya decide on a heater? Check out the type ones I mentioned. I find it works great and is fairly efficient!

GOod luck!

Andrew


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## Mr A (Aug 27, 2013)

I think the ban on a solid fuel heat source could have something to do with flammable vapors from vehicles and equipment, stored solvents, paint, etc. Even a NG water heater in a garage can be dangerous,pilot light igniting fumes. Most gas water heaters are on a raised platform now, but that wasn't code before many had to learn the hard way. Unfortunately, learning the hard way is how most building codes are upgraded.


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## Highbeam (Aug 27, 2013)

Mr A said:


> I think the ban on a solid fuel heat source could have something to do with flammable vapors from vehicles and equipment, stored solvents, paint, etc. Even a NG water heater in a garage can be dangerous,pilot light igniting fumes. Most gas water heaters are on a raised platform now, but that wasn't code before many had to learn the hard way. Unfortunately, learning the hard way is how most building codes are upgraded.


 
In my county, I can still install a woodstove in the garage but it must be elevated 18" just like a gas water heater for this reason. 18" to flame, spark, or glow is their actual comment.


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