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I can see my breath

Posted by on 5 November 2011

As the temperature drops in my neck of the woods, I begin thinking about how to keep my shop warm for the winter.

This post will introduce you all to my shop environment. I’ll cover the basics construction, which I used make my decisions about how to warm my shop. I hope this will help you design a way to keep yourself warm.

The Shop

I am lucky enough to have a separate building as my woodworking shop. It is just 20 yards or so out my back door. It is pole barn construction and is sheathed and roofed with “wavy” tin. The shop has a 30 x 60 footprint, 20×30 of which has a poured floor, so that is where my shop space is.

After a couple of winters of working in an ice box, I decided that my passion for woodworking was being snuffed out by the extreme cold of an uninsulated space. It can get down to 40 below around here and my cast iron tools soak up all that frigid air, making them painful to the touch.

First thing to do was to put up a wall along the edge of the poured floor. I took this opportunity to add a few outlets along the wall for 230 VAC service. This was a wonderful addition to the shop, but a topic for another post. The was insulated with fiberglass rolls and sheeted with plywood.

The next step was to make a ceiling. Yep, this shop was as basic as they come when I started working in it. Just open rafters. With significant help from my father-in-law, we put rigid insulation and steel on the bottoms of the rafters, giving us a 12′ ceiling height.

Now the 6 sided box that is my shop had two insulated sides. Two of the remaining sides were purely wall surface, with no doors or windows. The final wall surface is a big sliding door and the entry door. I installed 2″ (because it was $5.00 cheaper per sheet than 1 1/2″, go figure) rigid insulation on the walls, and 1″ foil faced in the sliding door.

I covered the walls with plywood for the first 8′ then OBS for the final 4′.

Alright, now 5 out of 6 surfaces are insulated. Just the floor remains as a poured surface. Now we can talk about putting a heater in, without going broke trying to maintain a reasonable temperature.

The 20 x 30 x 12 space is 7200 cubic feet. Based on this number, and my desire to keep the shop temperature in the 50-60 degree range, it was recommended to me that I needed around 30,000 BTUs (or 30K BTU, look at the Very Big and Very Small numbers page to learn about metric prefixes) of heat.

I mulled over the options:

Forced Air

I had a 50K BTU high-efficiency forced air furnace available to me. We salvaged it from a house that was being torn down to make way for a children’s hospital.

Pros: Heater was essentially free. House heat is natural gas, so fuel supply was close by.

Cons: More BTUs than required, would it run efficiently? No natural gas line to the shop. Filter cost would add up quickly.

Electric Heat

My shop has a dedicated service line for power, so I have 120 Amp capacity.

Pros: Energy supply already in place. Easy to install.

Cons: Not the cheapest source of heat in my area.


I also had access to a few different models of propane heaters. My father-in-law, being the avid outdoorsman that he is, was willing to set me up an “Ice Fishing” heater.

Pros: Again heater were almost free, but under rated, so I would need to run more than one.

Cons: Would require the purchase of a tank (or two if I ran multiple heaters).

Decisions, decisions…

In the end, I chose to buy a 30K BTU “blue flame” heater.

Image courtesy of Northern

I also bought a 110 gallon tank from my local propane delivery service shop. The up front cost for this setup was much higher than a simple electric unit would have been, but I think I will make up the cost in energy savings over the course of a few years.

This heater will keep my shop at 50 degrees even during the depths of winter. For extra heat, I fire up a tube style heater.

Fire in a WOOD shop!

I’ve written a few posts about how you can control your tools, but for a heater application, you want the heater to control itself.

When we turn control over to the unit, we have to make sure the unit can keep itself operating safely.

The blue flame heater has sufficient safety features built-in. It has a thermostat to control the flame and a thermocouple to make sure the pilot light is burning. Should the pilot light extinguish, the flow of gas would be cut off.

The secondary heat source, the tube style heater, is a loose cannon. As soon as you plug it in, it atomizes the fuel, kicks on the fan and starts sparking. If the igniter falls down on the job, a stead spray of fuel will start collecting in the tube. Can you say time bomb?

This could spell disaster in a wood shop. I absolutely NEVER EVER let this heater run when I’m not in the shop. During the next post, I’ll show you how I control this beast.

Can you see your breath?

How about you? Is you shop heated? What kind of heater do you use? I’d love to hear about your situations and hear your questions about how to stay warm.




P.S. Check out the following posts to catch up with the valuable shop tips I’ve shared here so far.

Switched Outlet with Fuse

Router Table Switched Outlet

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