Simple explanations for plumbing problems

OO Fault on an Ideal Logic

Although this isn’t really a true fault it’s still a problem I’ve been requested to fix.

OO is displayed on the front of an Ideal Logic boiler when there is no demand. For a combi boiler that is:

  • Room thermostat set too low
  • Heating timer turned off
  • No hot water taps open.

To cure this fault (if there is no other fault) you will need to create a demand. Try one of the following: turn a tap on, turn your thermostat up or switch on the heating. As soon as there is a demand the OO should change to a temperature reading and either a radiator or tap symbol.

If you’ve got a demand such as a tap running or the heating is turned on and the OO is still displayed then there may be a fault with the boiler or the controls.

The most common reason is a thermostat that is turned down a little bit below the room temperature. Try turning the stat fully up. Try turning a hot tap on if the OO still won’t change. A tap symbol and a temperature should be displayed.

If this doesn’t work you’ll need to get a gas engineer or electrician to check you boiler or controls.

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