How to Troubleshoot a Bosch Tankless Water Heater

Bosch manufactures a line of tankless water heaters. A tankless water heater provides an endless supply of hot water and reduces energy costs. The heating element is covered under warranty for a period of five years. All other parts are covered under a one-year warranty. If the tankless water heater develops a problem, troubleshoot it before calling for service. Disconnect the power supply to the water heater before removing the cover.

No Hot Water

Step 1

Inspect the water supply. Connect the supply line to the blue inlet on the water heater.

Step 2

Disconnect the power, remove the cover on the water heater and reset the high-temperature thermal cutout. Push the reset button in the center of the cutout. Reconnect the power.

Step 3

Remove the cover and check the flow switch. The switch activates when hot water is turned on. If the switch does not activate, call for service.

Step 4

Turn the power selector screw to "Hi" with a screwdriver. Open the cover and turn the screw counterclockwise to loosen it. Push the screw from the "Lo" position to "Hi." Turn the screw clockwise to tighten it.

Problems With Water Flow

Step 1

Inspect the plumbing for restrictions. Pipe joints should not be sealed with plumber's glue. This can reduce the flow of water.

Step 2

Open the service inlet valve. Turn counterclockwise to open fully.

Step 3

Turn the shutoff valve on the water supply line counterclockwise to open fully.

Temperature of Water Fluctuates

Step 1

Turn the shutoff and service inlet valves counterclockwise to turn on the water supply fully.

Step 2

Shut off the inlet isolation valve on the water heater. Turn the hot water faucet on in a nearby sink. If there is a steady stream of water, the cold water is flowing into the hot water lines. Call a plumber to repair the crossover between hot and cold water lines.

Step 3

Remove the aerators on household faucets and remove sediment clogging the aerators.