Rheem 305, 505, 705 Error 00: An "LC" or "00" error code indicates the unit is beginning to lime up and must be flushed.

Tankless water heater · taken from the manufacturer’s manual, pages cited

Error code00

An "LC" or "00" error code means the unit is beginning to lime up and must be flushed before further damage occurs. The manual's first action is: “Failure to flush the appliance will cause damage to the heat exchanger. Damage caused by lime build-up is not covered by the unit's warranty.”

Model
Rheem 305, 505, 705
Display shows
00
Type
Error code
Source
Manual p. 12

What 00 means

An "LC" or "00" error code indicates the unit is beginning to lime up and must be flushed. p. 12

Common causes

  • The unit is beginning to lime up. p. 12

What to do

  1. Failure to flush the appliance will cause damage to the heat exchanger. Damage caused by lime build-up is not covered by the unit's warranty. p. 12
  2. After flushing, reset the LC fault code by turning off the power to the unit and turning the power back on. p. 12

Before you service the product, read the safety instructions in the manual p. 4.

If 00 is still not resolved

  • Immediately call your gas supplier from a neighbor’s phone. p. 1
    “Immediately call your gas supp lier from a neighbor’s phone.”
  • If you cannot reach your gas supplier, call the fire department. p. 1
    “If you cannot reach your gas supplier, call the fire department.”
Open the manual at page 12 All 305, 505, 705 error codes Manual details & download

This page summarises what the manufacturer’s manual says about 00; each statement links to the page it comes from, and quoted lines are copied word for word. It is not a substitute for the manual or for a qualified installer. ManualLib is not affiliated with Rheem. Found a mistake? Report an error.