Shop Heating Questions

[Steve Goetz]

I'm in the market for a heater for my garage/woodshop. How important is a sealed combustion chamber for the heater if I have decent dust collection and use hand tools regularly? The cost of a sealed combustion chamber unit far exceeds my current budget and would like to get something installed before the snow flies here in Ohio. This is the one that I'm looking at currently: https://www.menards.com/main/heating-cooling/heaters/gas-garage-heaters/mr-heater-reg-big-maxx-dual-fuel-forced-air-garage-heater/f260550/heating-cooling/heaters/gas-garage-heaters/mr-heater-reg-big-maxx-dual-fuel-forced-air-garage-heater/f260560/p-1444441204088.htm

I'm heating about 1,100 sq. ft. with 9"+ sidewalls with 3 drafty overhead doors. It's a log home so insulated walls is not an issue. Any other suggestions? I will eventually supplement the gas fired heater with a wood burner whenever I can find one reasonably priced, but wanting something to take the chill off soon. TIA.

[Andrew More]

The problem with heaters that burn propane and natural gas is they increase the humidity in the area. This is a good thing for a lot of cases, but not when you've got a number of cast iron surfaces. If you've got the money a minisplit can be a better option. There are even DIY kits on the market to reduce the cost of installation.

[Steve Goetz]

Yeah, I've been kicking that idea around as well. I really like the idea of the mini-spit and the DIY kits look very appealing! I have my eye on the Mr. Cool DIY kit, but the cost is a bit much for me now. I do appreciate your thoughts on the humidity issues...I remember reading about that on this site once before and it slipped my mind!

[Frank Pratt]

That heater you linked to is vented, so no worries about humidity or CO emissions. It's the unvented propane/natural gas/kerosene heaters that should be avoided. If you have decent dust collection, an unsealed combustion chamber will be no problem. You just need to blow it out occasionally. That heater will work well, but you'll need to do something about the drafty doors.

I have a residential type natural gas furnace in my shop that isn't sealed. Every fall I service & clean it & there's just a light accumulation of dust inside the combustion chamber.

[Jim Becker]

Steve, the MiniSplit will be worth the investment and with Mr Cool, you can do the install yourself. And you get summer benefits, too.

As to the gas heaters...unless they are vented to the outside with makeup air available, humidity will be a huge negative factor. Unvented is no longer permitted in some parts of the country, too, but if they are for sale locally, I would assume there's no prohibition.

[Steve Goetz]

So to confirm, as long as I buy a vented gas unit, humidity will NOT be a concern? Though I'd love to put in a mini-split unit, my budget will not allow for such an expense at this time. I figure if this gas unit will work, I can get a couple of years out of it, sell it, and then put in a mini-split unit.

~Steve

[Jim Becker]

A vented gas heater can be pretty effective in keeping you reasonably toasty while insuring greater safety. You MUST pay attention to the venting requirements, however, and that includes the specific type of vent pipe and outdoor accommodations including positioning between exhaust and intake. IE, pay attention the instructions.

[Mark Bolton]

So to confirm, as long as I buy a vented gas unit, humidity will NOT be a concern? Though I'd love to put in a mini-split unit, my budget will not allow for such an expense at this time. I figure if this gas unit will work, I can get a couple of years out of it, sell it, and then put in a mini-split unit.

~Steve

The unit in your link is a vented unit with fresh air intake so you have no issue with moisture. Its completely correct that an unvented unit dumps gallon of water for every cubic foot of gas. Stay away. The unit you posted pulls in combustion from the exterior and power vents combustion air to the exterior. Just keep in mind if you use their venting kit there is a pretty large additional expense for the vent kit so your not looking at the price of the unit only. Those MrHeater sealed combustion units are a good value. Electronic ignition, power vent, etc. If you can locate it very close to an exterior wall your costs will be the lowest possible with that option.

No different than any sealed combustion option youll have to blow out the heat exchanger periodically but other than losing AC in the summer they are a good option. Its a big jump to a MrCool.

[Bryan Lisowski]

A pellet stove may be your best option, easy to vent and generally don't add moisture too the air. The biggest negative may be having to give ups some floor space.

[Jim Becker]

A pellet stove may be your best option, easy to vent and generally don't add moisture too the air. The biggest negative may be having to give ups some floor space.
May not be permitted in the OP's area but could be considered. The gas version is a bit easier to maintain a temp long term when one isn't in the shop every day because it doesn't need to be "fed".

[Ed Aumiller]

That unit, if vented properly, would work great and be very efficient. Humidity would not be an issue..


If room permits, consider a high efficiency standard propane furnace. The savings over the first year will probably pay for the difference in price as
you can get 90-95% efficiency. Plus they can use 2" pvc for both the intake air and exhaust vents. By using outside air for the furnace, it reduces
bringing in cold air for the rest of the room.

[Dave Seng]

I just installed a 75K BTU unit that is very similar this past Monday. The power vent on these units carry out all of the combustion byproducts, including the moisture from burning propane or natural gas. I use mine to keep the shop around 50F at night and fire up woodstove during the day while I'm out there working.

[Ray Newman]

Someone mentioned a pellet stove. I had my detached shop built in 2001 and looked for an insurance carrier. All wanted know if I had a wood or pellet stove as they would not write a policy if the building had wood/pellet stove heating. In 2019, I changed my insurance carrier and those I queried about coverage told me the same.

[Steve Goetz]

Jim, you are exactly right. I would love to put in a pellet stove, but the temperature maintenance would be too much to regulate now since I'm only going to be in there "part time"....for now. I will likely get a smaller wood burner stove to supplement heat when I find the right one!

~Steve

[Steve Goetz]

Good to know, thanks Ray!

[Lee Schierer]

One more safety concern. Since this heater is going in a wood shop, be sure to blow the sawdust off those heating tubes each year before heating season.

[Art Mann]

I have a Hot Dog brand natural gas heater that is nearly identical to the one in your link. I think it is 40,000 btu and it does a fine job heating my well insulated 1100 sq ft shop. It is vented to the outside so there is no accumulation of moisture as a combustion product. I would highly recommend it.

[Bill Dufour]

Natural gas or propane is cheaper then pellets. I think a heat pump might not be much, if any, more expensive for heating then pellets. Do they still make corn stoves?
Bil lD

[Andrew Seemann]

I have a Reznor 45K BTU in my shop in MN, but it is well insulated and not drafty and I don't have any overhead doors. It is good to at least -35F (lowest temp we have had here since I put it in). It is a standard power vented model, not sealed combustion. There are specific code requirements as to air volume, but at 1100 sq ft with leaky doors, it is unlikely you will have any problems with makeup air. Obviously don't fill the shop up with solvent fumes from spraying finish and then fire it up. You might look into the Reznors and Hot Dawgs; they cost little more, but they seem to be the standard unit heaters that most everyone uses.

Natural gas if it is available is almost always the cheapest way to heat, unless you have access to free wood (and even then you pay with your time).

I keep my shop around 50-60F in the winter, and then bump the temp up before I am going to be working out there. I'd say keep your shop at least 40F in the winter, to keep condensation off the tools. The wood also seems to like not having wide temperature spikes.

I did have a friend who used an unvented gas radiant heater in their shop for a while. It kept the place warm, but it did put a ton of water in the air.

[Ray Newman]

Art Mann: agree on the Hot Dawg propane heater. Been running one for almost 20 years and no regrets, no rust on the machines/tools, or any maintenance issues for the heater. Controlled by a low temp. thermostat set at 47 when I am not in the shop and when in the shop I turn it up to about 68 or so and it is warm in no time.

[Dan McGonigle]

I’ve been using a natural gas Modine Hot Dawg heater in my small shop for about 5 years. Shop is brick/plaster (19th century construction) with a cinderblock and brick facade bump out built sometime probably mid 20th century. Standing seam roof over typical T&G roofing boards. Completely uninsulated. I’ve been extremely happy with it and consider it my best shop investment. It does not have a sealed combustion chamber and I have never had a problem with humidity. I only turn it on when needed though. It’s properly vented and code compliant. That and a big window unit made my shop a 4 season workspace. Money well spent.