john wrote:
I`ve had a new boiler installed (Ferroli Tempra 30 - with integral
pump) & I`ve chosen to do the wiring myself.
The system is an S plan (boiler, 2 zone valves for CH & HW, room stat,
cylinder stat).

What I can`t figure out is the following:
The boiler has a mains cable (live, neutral, earth) coming out of it
which presumably needs to connect up somewhere. There is also a
junction box within the boiler which has 8 terminals. According to
the wiring diagram, I need to connect up terminals 1 & 2 (on the
boiler) to grey and orange outputs of the zone valves. (Terminals 1 &
2 currently have a loop wire between them)
This is confusing as I don`t know whether to connect both the mains
cable to permanent mains (which means the boiler would be on
permanently (unless I take out the loop wire between terminals 1&2 on
the boiler?) and also connect up terminals 1& 2 to the zone valves
Very confused - help !?!

John

First of all the boiler does need a permanent mains connection to run its
electronics so run a 3 wire flex from its L, N & E connection to the fused
spur that feeds power to the central heating system.
The normally open contacts of the two zone valves are usually wired in
parrallel and the two resulting volt-free wires are wired accross the boiler
controlling terminals, in your case 1 & 2,.
Of course, you take off the link between these two pins so then when either
of the zone valves is opened under the control of the room or cylinder
stats, the boiler operates.