How to Set Up a Direct Venting System for Gas Fired Boilers

What You'll Need
Tape measure
Cast iron piping
Masonry saw

It is essential for the safety of your home and family to provide direct venting for your gas fired boiler. Follow these steps to set up a direct venting system for your gas boiler.

Step 1: Measure from the Direct Exhaust Vent to the Chimney or Wall

Use your roof chimney to vent your gas fired boiler. If you have no chimney, drill a vent through an exterior wall. Measure from the direct exhaust vent, on top of or on the side of your boiler, to the chimney or wall, to determine the cast iron pipe vent length.

Step 2: Cut the Vent Hole

Use a masonry saw to cut the exhaust vent hole. It should measure 1/16 inch larger than the cast iron pipe nozzle to be fitted through it. Standard widths are 3 inches, 3-1/2 inches or 4 inches in diameter.

Step 3: Install the Pipe Vent Line

Attach the cast iron pipe sections from the boiler's exhaust vent to the vent hole. Cast iron sections will use steel push-in nipples for airtight assembly.

Step 4: Attach the Sidewall Thimble

A sidewall thimble will be included with your gas fired boiler. Attach it to the end of the exterior exhaust vent, with the screened side facing outdoors.