My Vokera Mynute boiler question

[peterduffy]

Hi folks, I wonder if anyone can please help me understand my boiler/system

I have a Vokera Mynute System condensing boiler

I have the vokera programmer fitted on the front of the casing which I believe is optional (after looking at the user/installation manuals)

basically I wondered how the system is wired in. I have what is called a S PLAN system (as in the manual) but can't make head nor tail of the wiring in the manual and would like to.

The boiler is working all ok


Thanks for any help offered

 

[Ray84]

Its got a 2 chennel programmer obviously for heating one side water the other. the clocks powered by the pcb via a 24v lead harness.
The boiler has a terminal strip which needs a constant 240v supply and can then be wired into the conventional S plan wiring

Ray

 

[peterduffy]

thanks for your reply

so basically the L N and E from the spur goes into the boiler to the main terminal strip - this then feeds the timer, which then feeds the S PLAn via M4, and the SL from the 2 ports come back to another terminal strip in the boiler called M5 which fire it up when demand is required?

 

[Ray84]

yes absoutly correct apart from programmer runs at 24v from pcb not wired from junction terminal m4 will have 2 wires one being CH on and the other HW on, feeding your terminal strip supplying valves, stats etc then when demand it will come back along from your junction terminal into M5 firing up the boiler until stats are satisfied on built in boiler stat reaches temperature

Ray

 

[peterduffy]

Thanks mate for your help

From the digram in manual - there also seems to be a L and N going from M5 to timer L N terminals also?

Also, why does it show the grey wire from the 2 ports (perm live) going back to the boiler ? Just orange could surely?!

 

[Ray84]

i see what you mean would it make sense (just what im guessing) m5 is your live and switch live to valves (grey would be constant 240v) then m4 is 2 browns which will go to junction strip then 1 side to room stat the other going off to cylinder stat, then when cylinder/room stat has demand back along into the junction then along the orange on m5
so when clocks off orange isnt 240v while grey is then on demand orange becomes live at m5?
also see the 240v supplying the clock must be for switching while the clock itself is 24v
Ray

 

[peterduffy]

i'll have a close look again!

if the timer were to fail in years to come how would I be able to prove it is faulty ? I have both manuals here and have been keen to understand it all

 

[Ray84]

when you have a demand at the programmer and both wires at m4 are dead the switch in the programmer will not have made, you could link the switch out doing the job of the clock (black to purple wire on 1 side and red to grey on the other from my picture) and see if it brings system on
(guessing here)

Ray

 

[peterduffy]

yeah there is a link (removed now) but says to test - allow boiler to be on withotu demand

 

[Ray84]

yeah but then your proving the boiler will fire but not indicate where the fault lies (if its zone valve, stat or programmer)
manually making the zone valve will do just the same job

Ray

 

[peterduffy]

I see ht you mean, I suppose if neither hot water or heating worked it would rule out the zone valves and stats as be looking at programmer/pcb? power in to prog?

 

[Ray84]

yeah if they both packed in id assume it to be a boiler or clock fault. in which case id manually open one of the valves (which will always be 240v via the grey on m5) if the boiler starts problems the clock, if it didnt start faults with the boiler.

Ray

 

[peterduffy]

good idea, or possibly test for 240v at stat terminal in wiring centre - as sealed i'd be checking pressure first

thanks for helping Ray