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Cleaning a Marathon Tank
Sediment: Sand and Scale

Without a water softener and/or water filters, sand, dirt and hard water scale accumulates in the bottom of water heaters, even self-cleaning water heaters. A frequently asked question on our tech service line is how to clean a Marathon tank. Yes, there is a drain valve at the bottom of the heater but this sometimes cannot remove all the debris.

Most consumers don't clean their water heater on a regular basis. Most only do it when they are forced to change the lower heating element. This is where the wet-dry vac method comes in handy. With the lower element port open, debris can be vacuumed out.

Instructions

  1. Turn off power at circuit breaker panel to the Marathon water heater.

  2. Close the valve that supplies water to the water heater tank.

  3. Note: Always remember to open a hot water faucet or 2 when draining or refilling a Marathon. This will allow air into the tank while draining and let air out of the tank when filling, speeding the process and preventing equipment damage. Drain the tank through the tank drain valve at the base of the water heater.

    Note: Make sure drain hose is connected or tank is being drained in a contained area to prevent water damage.

  4. Remove lower element covers. Double check that the power has been turned off. Use a curcuit tester, meter, etc. to be certain power is off.

  5. Remove lower element wire leads (2).

  6. Remove lower element using element wrench.

  7. Assemble universal adapter to vinyl hose.

  8. Attach adapter assembly to wet/dry vacuum.

  9. Insert vinyl hose into lower element hole.

  10. After cleaning is completed reinstall — element; wiring; covers as described in step numbers 6–5–4 above.

  11. Close drain valve.

  12. Open water supply valve to tank.
    Note: Always remember to open a hot water faucet or 2 when draining or refilling a Marathon. (This will allow air into the tank while draining and let air out of the tank when filling, speeding the process and preventing damage.)

  13. When tank has completely filled, reset circuit breakers to restore power to water heater. Never restore power to an empty or partially filled tank. Upper element will fail if tank is dry fired. The Marathon water heater is equipped with a fused upper element, and will have to be replaced if unit is dry fired.

Note: Failure to follow these instructions may cause damage to your Marathon water heater.