Both use the same fault codes to indicate the issue but display them in a different way depending on what control panel you have.
If you have the rotary switches the red led will flash a number of times then pause then repeat the flashes again, you then need to count the number of flashes and then check the list below to see what triggered the fault.
If you know why it failed you can do a “soft reset” by turning the power selector switch to the energy source it failed on then back to zero (off) three times within 5 seconds. If this doesn’t clear the fault see further down this article.
If you have the Duo Control Panel it will display a red “!” on the left of the display. If you press and hold the space heater button it will illuminate a number of bars, the number of bars showing correspond to the fault code number. See table below.
To do carry out a “soft reset” on this panel you need to hold the “heating” button and the “+” button this should reset the fault. If this doesn’t clear it see further down this article.