How to Vent for Water Heaters

If you ever had a gas-fired water heater you probably have seen galvanized sheet metal venting running from the top of it to a chimney.

Venting Out Chimney

When a gas-fired water heater burns the natural gas it uses to heat the water, it produces toxic gases as a byproduct of that combustion. These gases need to be vented out of the home. While it may look complicated to run galvanized sheet metal venting, it is actually a fairly easy task and only a few tools are needed.

Step 1

Locate a spot on the chimney where you want to vent your water heater. It should be at an elevation above the vent outlet on the water heater.

Step 2

Use your hammer drill and drill a 4-1/4-inch hole into the chimney.

Step 3

Measure the distance from the vent outlet on the water heater to the hole you drilled in the chimney.

Step 4

Purchase the required amount of 4-inch galvanized vent pipe along with any elbows you need for turns.

Step 5

Install the 4-inch galvanized vent pipe from the vent outlet on top of the water heater to the chimney. The 4-inch galvanized vent pipe is connected together by inserting the crimped end of one piece into the non-crimped end of the next piece. Screw each connection together with four sheet metal screws.

Step 6

Cut the vent pipe as necessary with your snips to make shorter pieces. Each cut piece will need one end crimped with your pipe crimper so that you can connect it into the vent pipe system.

Step 7

Caulk each connection with high temperature silicone caulk---this includes where it enters the chimney.

Step 8

Support any vent pipe that is over 5 feet in total length with galvanized hanger strap. The hanger strap should form a hanger in the shape of the letter "U". Each end will be screwed to a ceiling joist with the pipe resting in the middle.

Venting Out Exterior Wall

Step 1

Locate a spot on the exterior wall where you want to vent your water heater out. This location should be at an elevation higher than your water heater vent outlet so that the pipe pitches up toward the exterior of the building. Drill a 1/4-inch hole from the inside out to use as a reference point.

Step 2

Go outside and locate your 1/4-inch reference hole. Using that as a center point, drill a 5-inch hole through the exterior wall with your hole saw. Make sure the exit point is at least a foot above the ground, or above the highest expected snow level for your area, so the end of the pipe end won't be blocked.

Step 3

Measure the distance from the water heater vent outlet to the exterior wall and purchase the required amount of 4-inch galvanized vent pipe and elbows.

Step 4

Install the 4-inch galvanized vent pipe from the vent outlet on top of the water heater to within 12 inches of the exterior wall. The 4-inch galvanized vent pipe is connected together by inserting the crimped end of one piece into the non-crimped end of the next piece. Screw each connection together with four sheet metal screws.

Step 5

Cut the vent pipe as necessary with your snips to make shorter pieces. Each cut piece will need one end crimped with your pipe crimper so that you can connect it into the vent pipe system.

Step 6

Slide your 2-foot length of 4-inch B-vent pipe through the hole you drilled from the outside. Slide it over the end of the 4-inch galvanized vent pipe and secure it with four sheet metal screws.

Step 7

Caulk each connection with high temperature silicone caulk--this must include the spot where it penetrates the exterior wall.

Step 8

Support any vent pipe that is over 5 feet in total length with galvanized hanger strap. The hanger strap should form a hanger in the shape of the letter U. Each end will be screwed to a ceiling joist with the pipe resting in the middle.

Step 9

Take your 4-inch B-vent cap and line it up with the end of the B-vent pipe outside. Push it on to the pipe and twist it to lock it into place.

Things You Will Need

  • Tape measure
  • Hammer drill
  • 4-1/4 inch core bit
  • Drill
  • 1/4-inch drill bit
  • 5-inch hole saw
  • 4-inch galvanized vent pipe
  • 4-inch galvanized elbows
  • 2-foot length 4-inch B-vent pipe
  • 4-inch B-vent cap
  • Sheet metal screws
  • Snips
  • Pipe crimper
  • Galvanized hanger strap
  • High temperature silicone caulk
  • Caulk gun
  • Gloves