I have a 12' x 24' workshop I want to put a heater in. I was originally thinking electric heat, however, I am now wanting a natural gas heater. I have learned that natural gas is much cheaper to run than electric. What have you guys done in your shops as far as heaters? Does a natural gas heater need to be ventilated? Thank you in advance.

Need a little more info.

Do you have natural gas to your shop?  Running gas lines can be expensive.

How well insulated?

You can do vent free....but don't. Vent free adds tons of moisture to a shop and when it's cold the last thing you want is more moisture. I've had vent free garage heaters....better than nothing but never again.

I have a 80k BTU Mr Heater Big Maxx in my shop. Vented with 4in pipe. Also have a 45k BTU in my house garage. Vented with 3in pipe. Love them. Mine are propane since we don't have natural gas.

Natural gas pipe also has to be sized correctly. We can probably walk you through the sizes you need if you give us some specifics.

Usually, depending on your electrical rates, electricity will be the cheapest to install but the most expensive to use.

Go natural gas vented if at all possible.  

Your shop isn't that big though so you might be able to get by with an electric heater if it's well insulated.

Also, a through the wall heater might be perfect for your shop. If it's a long way to run natural gas lines(think $$$) you might install a wall heater with propane. Depending on the insulation level you might heat for an entire winter on one 100lb bottle of propane.

Above ^ you can do a vented wall unit that takes up little space.

Most, if the run isn't long, will only need a 1/2 inch line ran depending on the BTU requirement. Flex line, while more expensive can make hard installs much easier.

20 ib. propane tank with a tank-top heater.

cheap, easy, and portable.

Thank you for your post. I will certainly go with an exhausted heating unit, I don't need any condensation issues as you mentioned. My shop is insulated with foam board insulation (2" on walls and ceiling). I may add some batting later for additional warmth. My gas line will be a fairly short run, approximately 20 feet from the nearest access to the shop. I have not estimated the cost but I think it will be affordable. The heater I am thinking about is a 30K forced air BTU unit. What do you think about his from your experience?

I think 30k would be way too big. You have 288 sq ft. You have around R10 insulation which is a little light....especially for your area....but not bad.

How tall are the walls?


Using the rule of thumb of 40BTU per sq ft you should need roughly 12000 BTU. An 18k through the wall heater at 70% efficiency (most through the wall heaters run between 70-80% efficient...Usually less than 80%) would produce roughly 12.6k BTU of useable heat....depending on the efficiency rating.

I think an 18k would do it and definitely do it if you upped the R value of your insulation....especially in the ceiling.

20 ft run is simple. Definitely do it in natural gas.

Looks like Menards can special order a 22k btu vented heater for $670.

Will work but also will put tons of moisture into the shop. Especially a bad idea in a cold climate like the OP.

My dads shop has insulated walls but not the ceiling. He has a standing NG heater that vents up and out. It takes a few minutes to get warmed up but after a few minutes will throw off some alot of heat. It does a great job. I definitely recommend NG over electric. Also, keep in mind that for the exhaust to leave the building you need makeup air coming in. So, don't seal up the building so tight that fresh air can't get in.

The walls are 7 1/2 '. I was just thinking more BTUs would be better in this situation and make up for having a little less insulation. Either way it sounds like I should maybe add another layer of insulation. I will check with Menard's, haven't done that yet. Only Lowes and Home depot. Thanks for the response.

Is it on a slab or a framed floor like a storage shed?

Lack of insulation in the floor will lose some heat but the first area heat escapes a building is through the ceiling/roof so start insulating there.

You don't want to grossly oversize a heater. A little oversized won't hurt anything but grossly oversized isn't good.

I have a 45k propane vented heater in my house garage. It is about 700 sq ft with two garage doors and two walk in doors. I live in a warmer climate than you and the 45k is a bit too big but I had it sitting in a box in my shop so decided to use it. My biggest heat loss is through the two 9x7 garage doors. 30k would be plenty for what I use it for.

The floor is plywood.The frame is made of 2" x 10" treated pine. The frame from the floor is elevated above the ground so I can access the underside and use some spray foam insulation if needed. The trouble I am now having is finding a natural gas heater that is 20K-25K BTUs that can be vented.

Menard's has this direct-vent wall heater for like $670.

Thank you!

Go to local HVAC supply house. You want a Modine or Reznor. Know your square footage and insulation R value. They will help you size it. 

That's the one I was referring to.  Note that it's about 75% efficient.  Not the best on efficiency but the specs say it's rated to put out 16,462 BTU.  Even using the figure of 55BTU per sq ft you're still getting plenty of heat out of that unit for your needs.

Modine and Renzor make good stuff.  The problem is, the OP isn't heating a large space.  288 sq ft.  I don't think either company makes anything smaller than a 30k.

Unless you're going to heat it 24/7, go big on the heater.  I'd use 30-45k btu if it was me.  It takes some oomph to bring a shop full of stuff up to a reasonable temp when it's well below zero and windy.  

I have been using a 60k btu  propane heater with a 5000 watt and 3000 watt additional electric as needed in my 20x36 garage (read that as shop).  North 12' was well insulated (r19).  South 24' only had 1" foam on the ceiling.  Whole thing was kinda drafty.  In the worst weather it could take half the day to bring everything up to 60 degrees or so after having the heat off over night.

I may have opted for heating 24/7 if it was insulated better and not so drafty.  I'm working on that now.  Just got done with the roof and have replaced the leaky car siding with 4x8 sheets of  5/8 t1-11 on three sides so far.  Doing the 4th side over the next few days.