Project Guide

How to Install a Gas Tankless Water Heater

1
REMOVE THE OLD WATER HEATER
Remove old water heater  - Gas Tankless Water Heater
  • Turn off the water, gas supply valves and power.
  • Drain and disconnect the old water heater.
2
INSTALL A NEW GAS LINE
Install a new gas line  - Gas Tankless Water Heater
  • Install a tee and valve in the existing gas line if needed.
  • Using flexible gas supply line or black pipe, run a new gas supply line from the tee to a point where it can be easily attached to the gas line of the new water heater.
3
INSTALL NEW WATER LINES
Install new water lines  - Gas Tankless Water Heater
  • Tie in new hot and cold water lines to the existing water lines with copper pipe and run the lines to the new water heater.
  • Use bell hangers to hold pipe securely in place against the wall – this will also make it easy to apply pipe insulation later.
  • Clean the pipes and connectors before soldering to remove oxidation.
  • Apply flux to the end of the pipe, slip pipe and connectors together, heat the copper with a torch, and solder pipes together.
4
MOUNT THE WATER HEATER
Mount the water heater  - Gas Tankless Water Heater
  • Build a platform with 2 x 4-inch pieces of lumber that will allow you to mount the new tankless water heater about 4 inches from the wall.
  • Mount the tankless water heater securely to the platform.


Safety: Choose a location for the new water heater that will allow you to vent it to the outside easily.

5
CONNECT THE WATER HEATER
Connect the water heater  - Gas Tankless Water Heater
  • Connect the shutoff valve and the sediment trap to the water heater following the manufacturer’s instructions.
  • Attach the gas supply line to the shutoff valve.
  • Connect the water supply line to the water heater following the manufacturer’s instructions.
  • Turn on the gas, bleed the line if necessary, and check for leaks. After checking for leaks, turn the gas line back off until installation is complete
6
INSTALL THE VENT
Install the vent  - Gas Tankless Water Heater
  • Apply heat resistant silicone sealant to the vent shaft of the water heater, slip on a connector, and secure with a hose clamp.
  • Slip on a section of stainless steel vent pipe, slide on a retaining ring and fold over the taps to secure it in place.
  • Slide on an elbow and adjust it so that the opening is pointing in the direction where the water heater will vent to the outside. 
  • Drill a hole from the inside through the joist or wall for venting to the outside at a point that will be the center of the vent hole. 
  • Connect the water supply line to the water heater following the manufacturer’s instructions.
  • Outline a circle on the outside wall using the vent thimble and bore a 1-inch hole near the top of the circle using a spade bit.
  • Cut out the vent hole with a reciprocating saw.
  • Remove shingles or siding from around the vent hole to allow the flange thimble to rest flush against the outside wall.
  • Apply silicone caulk around the edge of the flange, then insert the flange into the vent hole.
  • Secure tightly with screws to the outside wall, and seal the screws with silicone. 
  • Install interior flange from the inside and run a section of vent pipe through the flange opening, securing each section with the tabs.
  • From the outside, connect a small section of vent pipe and connect the vent hood.
  • Replace the shingles or siding that were removed from around the vent opening.
7
TURN ON THE WATER HEATER
Turn on the water heater - Gas Tankless Water Heater
  • Plug in the water heater.
  • Insulate the hot water pipe coming from the water heater.
  • Turn on the gas.
  • Follow any specific start up procedures provided by the manufacturer of your new water heater.