Know what to look for when you need to replace your own tankless water heater. Many tankless systems are called POUs (point of use) and are located near the appliance or faucet area to provide on-demand hot water. If the need arises to replace the heater, follow these directions for an easy, safe and efficient project.
Utility Shut Off
When working around anything that is powered, shut off the utilities to ensure your safety.
Turn off the main water shutoff valve to the home or the cold water shutoff valve to the tankless water heater inlet supply line.
If operating an electric heater, turn off the breaker switch at the power supply panel.
If operating a gas heater, turn the gas off at the supply pipe to the heater or the main gas shutoff valve to the home. Check to see that the gas pilot light has extinguished.
Remove the hot water, cold water and any gas or electrical wiring to the tankless water heater. In most situations, the tankless water heater has connector tubing or piping supplying water to the heater in an inlet direction.
The hot water exit flow pipe from the heater will also connect to the home plumbing system. Remove these at the home plumbing source, and take care to not damage the connectors so you can reuse them.
Disconnect the gas line to the heater (if applicable).
Remove all electrical wiring to the heater. Be careful so you don't damage any connectors. Retain any connecting screws for reuse.
Remove the inlet water and outflow hot water connectors from the heater unit to be reused on the replacement unit.
Removing the plumbing may require using a pipe wrench, slip joint or tongue and groove pliers to accomplish twisting off connectors.
Disconnect the heater flue.
After the flue, water lines and all gas and electric are disconnected, remove the old tankless water heater. Be careful not to damage any surrounding area when removing a POU device that may be located under a sink or a mounted on a wall.
There may be some residual water seepage and dripping so be careful to clean up as you go along. Water left unmapped can present a safety hazard.
Install the New Tankless Heater
Follow the manufacturer’s installation instructions. Make sure to check all connections for proper fitting. Most POU tankless water heaters are mounted inside cabinets and come with mounting hardware.
Attach the tankless water heater inlet and outlet connectors to the home plumbing system. Attach either the electric wiring to the heating element or connect the gas to the burner unit. Note that usually only large tankless systems that supply water to the entire building will have a gas power source. POU devices always use electric power sources.