RTFM
http://www.potterton.co.uk/downloads/Potterton_Performa_24_Eco_HE_Install.pdf
Page 7
http://www.potterton.co.uk/downloads/Potterton_Performa_24_Eco_HE_User_Guide.pdf
Page 3
You may need pages 4 and 5 as well, depending on why you are asking the question.
We'll leave aside, as a reason for you asking here, the notion that you couldn't be arsed to do a Google search for yourself. FYI It took me about 2 minutes to find the manuals AND check for references to a reset control.
XXX, February 2016
