How to Install a Gas Heater for a Garage

RON HAZELTON:

It’s chilly out here today.  You know, this is my first winter here in this shop and already it’s become apparent that I’ve got to have some heat out here.  Now, I don’t need to keep this at a constant temperature, that is, a living temperature, but I do want to be able to get the heat up quickly when I need it.  So, I settled on this unit right here.  It's called the hot dawg. Now this heater comes in 4 different sizes.  30,000 BTUs, 45,000 BTUs, 60,000 and 70,000 BTUs.  This is the 60,000 BTU model right here and this is the one that's the right size for my shop. So let's get started.  We're going to put this up. There we go. Now this heater is designed to attach directly to the bottom of the joist. But in this case, I want it mounted at an angle, so I've added a couple of 2 x 6's up here and lag screwed those into the joist. 

Now since I'm going to be working alone today, one of the more challenging parts of this project may be hoisting this 80-pound heater up there where I'm going to attach it to those 2 x 6's.  To start with, I've wrapped a couple of cargo straps around the case.  A little research leads me to a marine supply store, where I check out things in the rigging department.  Now, to do the heavy lifting today, I decided to use this marine block and tackle.  It's designed to lift very heavy booms on sailing ships.  Lightweight, very strong, a little pricey, but it's a lifetime tool.  Now I'm going to attach it to this 2 x 4 that I put up earlier.  The lower end of the block and tackle gets attached to the cargo straps. Then I hoist the 80-pound heater upward as easily as a sailor would raise a mainsail on the mizzenmast.

Once in position, I clamp the mounting flanges.  And more clearance holes.  Next, I insert carriage bolts - and finally twist on nuts and snug them tight with a socket wrench. Now this being a gas-burning appliance, I of course have got to exhaust those gases at a flue.

So the first thing I'm going to do is attach this T-shaped piece of flue to the back of the furnace right here.  And I'll attach that permanently a little bit later on.  Now there's going to be a second piece of pipe that will go from the center of this flue right up through the roof.

And that means we're going to have to cut a hole up there that's exactly on top of this one right here. So let's take a plumb bob. This is the best way to do this.  I'm going to move it around up here until the plumb bob is centered directly over this flue.

Right, now I'll make a mark right up here at the top of the plumb bob line, right there. Next, I bore through the roof and insert a wire coat hanger.  Well, the coat hanger marks the spot.  We won't need that anymore.  So let me push this back down through here.

Now what I want to do is draw a circle 6 inches in diameter - now this is a lumber crayon that I have in here - I bore a half-inch hole on the edge of the circle, insert the blade of the jigsaw and make the cutout. Well, this is the flashing that's going to make the watertight seal eventually around our flue.

I'm going to set this about where I want it here. And that is, I want to center the large opening down here on the bottom over that hole that we cut in the roof.  That looks pretty good.  Now I'm going to reach inside with my lumber crayon.

Be careful because this is sharp here - I'm going to trace the outline of this oval shaped base here.  Then using a utility knife with a hooked blade, I cut along the mark that I just made.  Next, I apply sealant to the lower shingles, where the base will be sitting on top.

Then I slide the flashing underneath the upper shingles and into the circular cutout. Finally, I secure the flashing base with roofing nails.  This is double wall vent pipe. The inner liner's aluminum, the outside is galvanized steel.

Now the idea is that even though there are hot gases passing through this pipe, the outer jacket remains cool. So what I'm going to do is pass this up through that flashing we put on earlier.  The lower end of the pipe I connect to the vent coming out of the back of the heater.

The joints are held together with couplings that snap into place.  Back up on the roof, I slip a weather ring over the top of the vent and slide it down to the top of the flashing. Finally I set the vent cap in place and apply sealant to the nail heads.
With everything finished on the roof, I go back inside to make the electrical connections. Next I apply thread sealant to the gas pipe sections.  Tighten them together and finally connect the flexible gas line.  I installed the main part of the gas line and shut off valve earlier.

I've installed a programmable thermostat because out here in the garage workshop, I don't need heat all the time, just when I'm working. And the nice thing about this one is, if I'm coming to work at 9 o'clock, I can set this to bring the heat up around 8:30.

I can't tell you how glad I am that I put this unit in.  In the few weeks since I've installed it, the temperature hasn't gotten above freezing and this heater has done a great job of giving me heat where I want it, when I want it.