i have just installed a vaillant ecotec plus 637 and a megaflo unvented indirect cylinder, model 250i. the system has 2 heating zone valves for up stairs and down stairs and a dhw zone valve. i also have 2 room stat a wired honeywell t6360 for up stairs and a wireless honeywell hc60ng for down stairs. the boiler has it's own built in programmer and the megaflow has it's immersion heater. i have no seperate isolation switch near the junction box just a feed cable coming from the fuse box. i have the boiler running from a temporary supply at the moment and all the zone vavles manually open. basically i need to know how to wire it up, i only have a 3 core cable coming from the up stairs room stat and wonder do i connect striaght to the boiler from the fuse box and then back to the junction box because of the built in programmer and what should go where in the junction box. all the zone vales are honeywell 2 ports with 5 cables. i'm stuck and really need to finish this job any advise would be really helpful, also what do i do about the wiring to the megaflo with regards to the immersion? please help