If your up to speed on motors and dol starters etc,s plan and heating wiring is a peace of cake,y plan is slightly more hard to fathom when new to heating control wiring and fault finding,but you soon get to grips with it,for an s plan there are wiring diagrams on the forum so you could print one off and practise,its not as complex as you think,all controls have L-N-E then just MVs have grey(perm L)browns are switched either by a roomstat or cylinder stat,when calling for heat,MVs motor and the orange is energised(connected to switched live of boiler) simples! well done on passing the 2391
