Install a Tankless Water Heater for Hot Water on Demand along with the Savings of Gas over Electricity

Install a tankless water heater when your conventional tank water heater needs replacing because it isn't heating or is clogging your home's water pipes with debris. In this project, a clogged kitchen faucet started a home improvement journey through water fixtures and water-using appliances in the house to become a successful adventure into tankless water heating technology--on demand.

Safety Note: The flexible gas supply line for this water heater installation is corrugated stainless steel tubing (CSST). In rare situations, lightning strikes can cause arcing between the CSST and nearby metal conductors (e.g. another piece of metal pipe) causing a rupture in the flexible line. For this reason, all CSST installations must be directly bonded. Bonding uses a heavy gauge wire to safely conduct electrical energy to the ground significantly reducing the chance of arcing.  

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attaching a corrugated stainless steel gas supply line
Step 1

Install a Gas Supply Line for the Tankless Water Heater

Install a T and valve in the existing gas line and run a new corrugated stainless steel supply line for the tankless water heater. Building codes in many communities permit its use rather than conventional black iron for gas lines.

soldering the copper waterlines
Step 2

Tie in New Copper Waterlines for the Tankless Water Heater

Tie in new waterlines for the tankless water heater. Bell-hanger brackets hold the pipes in place to prevent contact with the wall and to facilitate applying pipe insulation. Clean copper pipe joints and coat with flux before soldering.

attaching the cover to the platform
Step 3

Build a Covered Platform to Position the Tankless Water Heater

Construct a covered vertical platform to position the tankless water heater so its vent clears the floor joists while passing through the outside wall. Secure the platform with Tapcon® screws that cut threads into concrete to anchor themselves.

mounting the tankless water heater to the platform
Step 4

Secure the Tankless Water Heater to the Platform

Hang the tankless water heater on the covered platform. A single screw will hold it temporarily. Secure it by driving screws through the holes on its mounting bracket into the platform.

connecting the supply line nut with adjustable wrenches
Step 5

Connect the Gas Shut-off Valve, Sediment Trap and Supply Line

Connect the gas shut-off valve and sediment trap and then attach the corrugated stainless steel supply line. Tighten the nuts at the connections with adjustable wrenches.

supporting the pipe runs with bell-hangers
Step 6

Connect Water Shutoff Valves and the Tankless Water Heater

Make connections between the water shutoff valves and the tankless water heater. Use bell-hangers to support the pipe runs. Solder the joints on the copper piping.

sniffing for gas leaks
Step 7

Use a Gas-sniffer to Confirm There Are No Gas Leaks

Turn on the gas and bleed the air from the line. Use a gas-sniffer device at each joint to confirm there are no gas leaks in the tankless water heater installation.

securing a connector with a hose clamp
Step 8

Attach Heater Vent Piping, Connectors and Elbows

Apply heat-resistant silicon sealant to the heater vent. Slip-on a connector and secure it with a hose clamp. Add and secure sections of vent pipe and elbows. Bore through the outside wall at the center of the vent hole.

fitting the metal wall thimble on the outside wall
Step 9

Install the Metal Wall Thimble through the Outside Wall

Trace the metal wall thimble and cut away the outside wall. Remove shingles as necessary for the thimble to rest against the wall sheathing. Install exterior and interior portions of thimble. Add remaining components of vent piping.

insulating the hot water pipes
Step 10

Plug Electric Power to the Water Heater and Insulate Pipes

Plugin the tankless water heater unit to supply electrical power to its thermostat and onboard microprocessor. Protect the hot water pipes with pre-shaped pipe insulation. Turn on the gas and press the start button on the heater.


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