How to Build a Wood Steaming System Using PVC for the Boiler

Building a wood steaming system using PVC for a steam box is an inexpensive way to steam wood for bending into shape for a shop project. Use schedule 80 PVC for all the pipe, fittings and connections. Live steam is extremely dangerous, so be careful when using the steam box. Operate the wood steamer outside in an open area where you will have access to both ends of the PVC steam box.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Hacksaw
• PVC primer
• PVC glue
• 6 feet of 4-inch diameter PVC
• 4-inch diameter PVC Tee
• 1 ½-inch diameter PVC pipe, 3 inches long
• PVC Reducing bushing, 4 by 1 ½ inches
• Two 4-inch PVC threaded female adapters
• Two 4-inch PVC threaded caps
• Handheld power drill
• Four 6-inch long galvanized bolts and 4 nuts
• 5-gallon oil recovery can with a telescoping spout and drain hole in the top
• Propane burner
• 3-foot length of 2-inch diameter radiator hose
• 2 band clamps
• Heat resistant plastic funnel

1. Cut the 4-inch PVC pipe into 2 3-foot sections. Insert them into the two ends of the 4-inch tee. Attach one 4-inch female adapter onto each open end of the 4-inch PVC pipe.

2. Insert the 4-inch by 1 ½-inch reducing bushing into the remaining opening (the Tee opening) of the 4-inch PVC Tee, and insert the 3-inch piece of 1 ½-inch PVC pipe into the 1 ½-inch opening of the PVC reducing bushing. You should have about 2 inches of the pipe sticking out as a nipple.

3. Lay the assembled PVC boiler on a flat surface with the PVC Tee in a horizontal position. Use a 6-inch drill bit with a diameter slightly larger than that of the stainless steel bolts and drill four equally spaced holes through both walls of the 4-inch PVC pipe below the centerline of the pipe. Measure and mark the holes before drilling to be sure the bolts are at the same level.

4. Push the four stainless steel bolts through the holes so the ends of the bolts protrude out the other side of the 4-inch PVC. Screw on the nuts to hold them in place. The wood will rest on these bolts to keep it off the bottom of the PVC pipe where water will collect.

5. Drill a hole vertically through the top of each end of the 4-inch PVC pipe near where the female adapter and the pipe meet. These holes will allow the steam to escape while you are operating the steam box.

6. Attach one end of the radiator hose to the 1 ½-inch PVC nipple and the other end to the spout of the oil recovery can using the two band clamps. The steam will pass from the can through the radiator hose and into the PVC steam box.

7. Set the oil recovery can on the propane burner, put the funnel into the drain hole and add 2 ½-gallons of water. The funnel acts as a relief valve if too much steam is generated, and it allows refilling of the can as the water boils away.

8. Light the propane burner and place the wood into the steam box on top of the bolts. Once there is a good head of steam built up, screw the two end caps into the ends of the female adapters to contain the steam.

Tips & Warnings

• Use the PVC primer and PVC glue to join all the PVC pipe and fittings. Allow all the glue joints to dry overnight between Steps 2 and 3.
• The propane burner and the can should sit lower than the PVC steam box to allow the steam to rise into the steam box.