if you have a "Y" plan system then you may not have enough wiresb for the ep2002 as you need a HW off wire which the radal 102 does not have but it will work with the "S" plan system
so the 102E may be the best choice
www.gascentralheatinguk.com
January 2009
You would be better changing a Randall 102 for a Randall 102 E.You get better settings and you dont have to change any wiring.Just rip the module off the backplate and put the new front module on the existing backplate.A totally different clock needs a rewire.