clock menu more-arrow no yes mobile

Revisiting Our Hybrid Water Heater Install

Ask This Old House plumbing and heating expert Richard Trethewey returns to a home he visited four years earlier to replace a faulty water heater.


  1. Unplug the electrical connections.
  2. Turn the gas valve off.
  3. Turn off the water supply to the current water heater.
  4. Drain the current water heater using a hose into a utility sink or a bucket.
  5. Break the connections on the current water heater by cutting the copper pipes with a pipe cutter and breaking the gas line nut connections using opposing force and pipe wrenches.
  6. Mount the new hybrid water heater unit to the wall.
  7. Use 3” PVC pipe for both the air intake piping and the exhaust flue products. Dry fit all the connections first.
  8. Once the dry fittings are set, use PVC primer and cement to make the connections permanent.
  9. Dry fit the copper water line connections into the unit and out of the unit using 1” copper. Be sure to clean each pipe with emery cloth for a tight connection.
  10. Make permanent connections on the 1” copper pipe lines using flux, solder, and a torch.
  11. Install a temperature and pressure relief valve on the water line.
  12. Connect the gas line piping using pipe wrenches and opposing force.
  13. Plug in the unit to an electrical outlet.
  14. Turn the gas valve back on. Check for any leaks using a soap solution. Bubbles will show a leak.
  15. Turn the water supply line back on. Check for any leaks in the copper pipes.