Is a 30,000 BTU heater big enough for a two car gar-shop with 10 foot ceilings? This would be a ventless natural gas heater.
OR....
Does anyone have a link for a conversion table for BTU needed per square (cubic?) foot?
Thanks!
Joe C.
Depends on where you are and how well insulated your building is.
-j
I heat a 630 cubic foot, three car garage with 11 foot ceilings with a
24,000 btu kerosene heater and a ceramic heat cube. The garage is pretty well insulated including foam backed door panels. It also shares a wall with the house.On moderated days (around 40 degrees) I can usually let the kero heater run for an hour or so, turn it off and the cube can keep up.
On really cold Kansas days (0 to teens, both units can keep the temp around
50- 60 depending on wind.
Depends on a few variables! How well insulated, quality of the doors and windows, outdoor temps for a start. But, a well insulated garage should heat fine with 30,000 BTU. I have a 24'x38' garage with 10 foot ceilings that I heat with 50,000 BTU, insulation is good, but could be better, but the furnace is plenty large. North Dakota climate. I would avoid a ventless heater though. Our area they are not even allowed by code. Greg
Hmm. 630 ft³ ÷ 11 ft = 57.27 ft². If your garage were square then it would be about 7.57 ft on each side...
What kind of cars are you parking in there?
Ok, yeah, I guess I could've given some more details. I live in Chicago which means temps down to zero (occasionally, more like teens), ceiling of the garage is drywall with 12" of insulation blown in, but the walls are bare brick. Door is relatively well insulated. Garage dimensions are: 18' X 21' with 9' ceilings (not 10" as in original post). I wouldn't do ventless with kerosene or propane (do they even make them?) but how about with natural gas?
Thanks again,
Joe
IMO, not going to make it. I have that sized heater for my shop (propane) , about the size of yours. I get a 30 degree temperature rise, so when it is zero outside, plan on 30 inside. From the end of December until the end of February, I do very little in the shop. Add some insulation on the walls and you will get better performance. If I was buying a heater now, I'd go for a variable model from 30 to 80,000 Btu. If I was going to spend every day out there, I'd install a small furnace. Ed
Geez Ed, here I go agreeing with you again! (ABPW!)
To the OP Those bare brick walls are going to be a killer for heat. Some 2x2 furring strips, some 1-1/2 styrofoam, plastic, and a few pieces of sheetrock would help alot! When you were talking ventless I was assuming a ventless wall mount heater. You can buy wall mount vented heaters too, propane or natural gas. I still caution against a ventless heater. I think you will need at least 60,000 BTU, maybe more unless you add some insulation to the walls. Although a 30,000 may buy you some comfort on most days. A Reznor or Hot Dawg heater is really the way to go. Greg
Maybe RonB is a Shriner?..*S*
Ron,
I think you might have dropped a zero on that cube. Wouldn't 6300 cu ft be more reasonable for a 3 car garage???
Tom Veatch Wichita, KS USA
Hi Greg. What part of N.D. are you in? I see that Menards has the ventless type heaters in Fargo. I'm surprised they can sell them if they are not code rated. I think that Harbor Freight has them as well. Ciao',
Paul
First, the required BTU's are *NOT* a function of volume, it is a function of heat loss. Heat loss is a function of area, insulating value, and temperature differential with the outside.That said... It's complicated.
When I tried to figure this out for my shop ( 500 sf over a 2-car attached garage, 5.5" fiberglass in the walls/floor and a foot over the ceiliing, similar climate, northern NY). I ended up guessing at 2 10K BTU toe-kick heaters. In retrospect, could have gotten by with one.
You could approach this problem imperically. That is, borrow some electric heaters (if you have enough circuits) and see how they perform. If you could get four of the little 5K BTU jobbies going and see how they perform. I would think that 20K BTUs on a chilly day would be a goos starting guess give you a sense of how much oomph you need.
I would be concerned with dumping all that water vapor (the result of natural gas combustion) into a space with cold cast iron. Unless you always keep the space heated, that water vapor will condense on the cold cast iron and rust it.
-Stvee
What? a type o on the wreck? It could never happen. Joe
Fargo. Not allowed in the city of Fargo. Out in the sticks you can kill yourself anyway you want, so they can sell them. Here in the big city we have codes to prevent you from doing that! Just mention non-wented heaters to the mechanical imspector and watch him get excited! Greg
The procedure to measure heating cooling needs etc is I believe called a Manuel J....Not sure but one of my sons is in the heating business and he wipped out his clipboard and figured out what I needed in about
10 minutes....Bet a local heating/ air contractor could tell the OP just what he needs... BUT yea you know damn well he would want to sell you a heater...Bob Griffiths
Hmmm. I'll have to check the codes here in D.L. I was thinking of getting one for my shop. One thing I don't like (as mentioned elsewhere in the thread) is the high condensation you get going from 20 degrees up to 65 or so with the gas heaters. I have a couple of electric heaters now, but usually blast a small gas heater to preheat the shop quickly. I run around wiping everything down as it heats up to fend off the rust. On another aside, I just got an email from the wife & it looks like we're getting a Menards in D.L. Woohoo! Not a Rockler or Woodcraft, but pretty big doin's for us.
Cheers,
Paul
After researching, I got the impression that what the best method would be to have someone with really good experience to "adjust" the formulas. In theory the formulas work. They are a simulation, and with all simulations, they simplify/round/estimate/assume. It really depends on the sophistication of the algorithm. Does it account for the size/quality/tightness of windows and doors? It probably works reasonably well with tight new construction, goes downhill with 100-year-old houses where there is alot of leakage and you don't know what's in the walls.
My gut says that a formula in the hands of the inexperienced could yeild results that were off by a factor of two. In this case, a poorly fitting garage door could double your heating needs. The trick is telling the difference between an experienced heating pro and a hack with a formula that only takes into account wall size and assumed insulation.
-Steve
Condensation is from non-vented heaters, vented heaters do not create condesation in the shop as it is vented outside. As for Menards, I rarely go there! The one in Fargo is so damned busy all the time it takes over an hour to get some sticks if you get them out of the yard. I hit the local yards, Simonsons, Crane Johnson. Most of the big box stores' prices are not any better than I can get else where, and get help that actually knows their product too. I may hit Home depot, Lowes or Menards on a sunday when the locals are closed. If D.L. gets a Menards, you will lose the local lumber yards, perhaps a hardware store too! Greg
preheat
This is true, and I generally support the "small guy" over the big box retail, but there is an attitude at some of the places in town where if "you don't like it you can go to Fargo". I am also willing to pay more for service, but do not like being gouged. If the service is not there, then you may as well go for price. I agree totally with you however and the places I do frequent that give me service may be hurt. That to me would not be worth the convenience and slightly lower prices. I guess I just want to have my cake & eat it too. Also thanks for the tip on the vented /nonvented condensation problem. I guess I will look into punching a hole in the wall. Not really a big deal I suppose
Paul
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