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School me on shop heaters

Wheelerfreak

Wheelerfreak

Chronically stupid
Joined
May 20, 2020
Member Number
537
Messages
904
Loc
Near TA, NM, out in BFE
My shop currently has both a barrel stove and a non vented 15kish BTU propane heater and I want to replace them both with just one 75-80k BTU heater. Looking at a Mr. Heater Big Maxx. It is a vented heater, which I like since the current propane is not and I'd rather not kill myself with CO. Barrel heater is kind of a pain since it takes a while to get to heating and then I have cleaning and feeding to do to it. I like the ease of use of firing up the heater and going to work, I know lazy:flipoff2: Can I vent the Big Maxx heater up through the existing flue for the barrel heater or will it not draw right since the Flue is 6" and the Big Maxx uses a 3-4" vent? Do they need to be ceiling mounted or can I make a rack 3-4' tall to mount it on? I'd prefer not to have 100#+ hanging off the ceiling.
 
I had a similar heater in my old shop. I didn't like it at all. It pulls combustion air from the room and then (obviously) vents it outside. This pulls a draft from anywhere it can, like garage doors, wall seams, etc. It actually made the shop feel colder when it was running. It's also a non-condensing setup, so it's only going to be ~80% efficient, so you're throwing money outside for a heater that in my opinion, doesn't do great.

I would track down a heater that pulls combustion air from the outside, it will make all the difference. I ended up switching to a pellet stove after a year and kept the propane for backup when I wasn't around to feed it. Keeping the same set temperature, the shop was much more comfortable to work in.

In my new shop, I insulated the hell out of it when I built it, so I'm opering on a single 5kW electric heater (~17k btu) for a 2500 ft2 building. I pay for that convenience with my electric bill, which will push $200/month for 3 months out of the year just for the shop.

I bought a used furnace that I plan to install, but have not done so yet.
 
My shop is 30'x40' insulated. I use a 55,000 btu forced air heater to bring the temp up. Then I turn on a wall mounted 30,000 btu propane heater to keep the temp up. I have a couple fans up in a couple corners to help push the warm air down. It'll stay around 75 inside when it's in the 20s or 30s outside.
 
Wheelerfreak said:
Can I vent the Big Maxx heater up through the existing flue for the barrel heater or will it not draw right since the Flue is 6" and the Big Maxx uses a 3-4" vent? Do they need to be ceiling mounted or can I make a rack 3-4' tall to mount it on? I'd prefer not to have 100#+ hanging off the ceiling.
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yes, you can run even just a dinky water heater through a 6" flue, don't worry about it.
There's a chart in the national gas code? about flue size/length and max/min BTUs to vent into it.
You will however need to replace the woodstove entirely, as they don't like solid fuel and gas/oil venting into the same flue for whatever reason. Iirc it's something to do with acid production causing rust

of course you can make a rack for it, if it turns out there's like access panels and shit on the bottom just make the rack a couple feet taller and hang it from the rack, dummy :flipoff2:
 
I use an oil stove, just light it and forget it no power needed. It will run for as long as there is oil in the tank and I even mix in waste oil.
 
I've got the 45k Mr Heater unit...does alright, nothing special. Code up here needs stupid expensive stainless vent, so can't really comment on what you might need down there.
 
SomeGuy said:
I've got the 45k Mr Heater unit...does alright, nothing special. Code up here needs stupid expensive stainless vent, so can't really comment on what you might need down there.
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I'd imagine it should be stainless, isn't the exhaust acidic? I was hoping to be a cheapskate, but that usually ends up bad. I've been reading reviews and seems like the Big Maxx is getting mixed reviews. 93% efficiency LP heaters are running $1500ish and up.

I'm not going waste oil since I don't have access to enough to run it and being out in BFE it's too far to get into a a city where I might be able to find a source.
 
Wheelerfreak said:
I'd imagine it should be stainless, isn't the exhaust acidic? I was hoping to be a cheapskate, but that usually ends up bad. I've been reading reviews and seems like the Big Maxx is getting mixed reviews. 93% efficiency LP heaters are running $1500ish and up.

I'm not going waste oil since I don't have access to enough to run it and being out in BFE it's too far to get into a a city where I might be able to find a source.
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If I had a bigger garage, I might even be tempted to find a regular ol' household furnace, use that, and run a bit of duct...far quieter (the mr. heater units are pretty loud) and more even distribution. You can often find used furnaces out there for pennies where people have upgraded.
 
Cheapest forced hot air furnace you can find on CL. Stick the thermostat in the opposite end of the shop. Add a box fan somewhere in between if the heating is too uneven.
 
At work in our 50 x 60 foot shop they have an LP gas fired chicken house heater, hangs from the ceiling and keeps it nice in there, I can find the brand monday if you'd like. Kinda like in the boat world, if you search for things from other worlds it turns out cheaper than a "shop heater"
 
I got an 80k mr heater in my shop. I vented it through the roof because I'm too cheap to buy the stainless for horizontal venting. I'm happy with the heater but its definitely not built as solid as a comparable reznor or modine.
 
Forced hot air oil furnace. Friend of mine has one out of a trailer home in the 2 bay auto shop he works at. Runs it off diesel 5gal at a time because the owner doesn't have his shit together enough to hook up a tank lol! They've had it like that for 3 years now and it keeps it toasty in there.

Fuck propane. It's way too expensive for the BTU's once they screw you with delivery fees ect. if you have a bigger tank, and too much of a pain to haul smaler tanks in to get filled. Oil heats the way to go for convenience.
 
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