Blue flame heater selection help needed

[sicklyscott]

Hi Everyone,

I've searched through the forums here and I realize using a blue flame propane heater for long term use is rather controversial. Before you start yelling at me and telling me to buy a G73 let me first explain my situation.

The structure
My dettached garage is 11 x 22, the rafters are about 7 foot high and its a "regular" pitched roof. There is no drywall, no insulation and no ceiling. I would consider it to be drafty. The structure was built i'm assuming in the mid-50's using planks covered in shingles, which was then covered in vinyl siding. The 2 "windows" were covered over with plywood and then sided over as well (I say "windows" because it's basically 4 panes of glass trimmed in wood, no opening, closing or double pane stuff). I live in NJ, right now we're seeing daytime temps of 32 and night time in the teens to low 20's.

The Use
I currently have a 91 Miata that I will be using as a track toy. I don't care to keep the garage warm all the time, I just need it to be warm enough for me to handle some tools and do some wrenching in the winter. The other day it was about 50 degrees in there (warm spell) which I thought was probably the lowest temp that was comfortable. I would probably fire the heater up on the occassional week night along with maybe weekend days. I work 12 hour days and go to grad school on the weekends, not exactly an abundance of free time.

The Dillemma
I've been eyeing a ProCom 20k BTU blue flame propane heater that I've found at Northern Tools and Harbor Freight. This heater has gotten some good reviews, however I can't seem to pick one up locally, although the Harbor Freight by me has a 10k BTU unit and a 30K BTU unit. I feel as though the 10k BTU unit might be too small, it says it'll hande the sq ft but because of the draftiness of the structure would it even work? The 30k BTU unit is overkill, howver it's available today, would it be a waste of fuel to buy such a large unit? I also saw that Tractor Supply has a Mr. Heater 20k BTU unit, although it is more expensive than the rest and I've heard it's rather gas hungry. By the way, these are all LP gas, not NG.

Cliff notes:
Drafty ~240 sq ft garage
Looking for the garage to be 50-60 degrees when needed (not all the time)
Three blue flame propane heaters to chose
- 10k BTU Procom
- 30k BTU Procom
- 20k BTU Mr. heat

Your thoughts and suggestions would be appreciated!

 

[lawfarm]

I posted a rather lengthy post on my experience with a blue flame, ventless heater recently (see Vented/Ventless Big Maxx... on the forum below).

My garage is a 2.5 car, and has about 2-2.5x the square footage of yours, and I had a 30,000 BTU heater. My garage is very well insulated, however, and is attached to the house. I suspect that a 10K heater would likely not do a good job for you. The 30k heater will probably be overkill, but with a drafty location, it might not be as much of overkill as you think.

The problem that I'm concerned you are going to have is the slowness of the heaters. If you want to keep the garage above freezing by having the heater always on, that'll do the job. But if you want to be able to come home after work or school, fire up the heat, and be able to work in comfort within a reasonable time, you'll be disappointed. The ventless, not forced air heaters take a long time to warm up a garage...especially one full of cold tools and a cold car. The heat doesn't circulate well, so you'll have a warm spot by the heater, and a cold spot on the far wall. Even if you use a fan, you just can't get the heat around where you want it. The solution, then, is to turn the heat on early (turn it up in the morning if you want heat that night), but that gets expensive, and you still get warm spots and cold spots.

I used a blue flame NG heater for a year. I now have a Big Maxx. The difference is night and day. If you search, you'll find a post on here where I said the ventless were workable and I was pleased with mine. That was before I experienced the forced air in my garage (I've had them in shops before). If I want to maintain a temp (40 degrees, e.g.), my 45K BTU Big Maxx runs far less than the 30K ventless did, and I get a consistent temp across the garage. If I want to warm it up to work in there, I turn up the thermostat about 10 minutes in advance, and it's toasty by the time I get a brew cracked open.

If you can do vented/forced air, I'd strongly recommend it. Initial purchase cost will be double, but it will make up for it with efficiency and comfort.

If you have to do the vented, I would not do 10K. I would do the 20K at the very minimum...especially in a drafty garage. I would also look at a fan on a pedestal to put in front of the heater to try to circulate air, but I wouldn't expect perfection from that setup.

I think the square footage ratings on the ventless heaters assume well-insulated, tight construction (e.g. a room in a house), and are pretty aggressive estimates. I don't think the 30K btu would be overkill for your space, based on my experience. The 20 would probably do the job...the 10 won't cut it.

 

[sicklyscott]

Thanks for the response Lawfarm.

I weighed my options the best I could, to Lawfarm's point above, the 30k unit will be overkill and I think will create a big "hot spot" in front of it. Where i plan on putting it, it'll be right by the car which won't help things. I'm going to go with the 10k unit and put a fan by it. I realize this isn't the best solution but if I get creative with my garage layout I think it'll be sufficient to keep me from freezing. I've come to the realization that I don't need to be warm, I just need to tolerate the temp in the garage, 50 degrees would be good enough. Plus it's cheap enough that if I need a second one it won't be a problem.

I'll post back up once I get it up and running.

 

[lawfarm]

Good luck with the plan.

One thing I found with my ventless heater was that 90% of the heat went straight up, to the ceiling. If you can, I'd try to space it out from the wall a bit, and put your fan directly above it. Maybe mount it so that it is 6" out from the wall, and put the fan above it blowing out, away from the wall (if you know what i mean).

With mine, at one point, I built a sheetmetal shroud to push the air further away from the furnace...but that just moved the hotspot a bit further out. Fan works much better.

Good luck.

 

[logguy]

Go with the 30k model. You can operate it on LOW, MED or HI. low is about 10k BTU. There are specific requirements for clearances afound the heater. It will get VERY hot within 4 feet of the heater.