Famous How To Flush A Tankless Water Heater References. There is also a safety hazard if the tankless water heater is plugged in while doing a flush. [1] this can be done by shutting off the main gas or turning off the circuit breaker for electrical devices.

Close off the valves for the hot and cold water and replace the filter (s) firmly. Web how to flush a water heater you'll have to drain a water heater in order to flush it. If you have a gas water heater, turn off the gas at the source.