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wiring problem s plan

Discussion in 'Plumbing and Central Heating' started by terence7556, 6 Aug 2010.

  1. terence7556

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    im having trouble with using the s plan in the honeywell book, page 2, sundial s plan. i have a fused spur under the boiler, 240v on the supply side direct from the ccu and on the load side a twin &earth to the wiring centre and also a short length of flex into the boiler 500mm above.
    on the wiring diagram the lower right hand box is a t&e from the boiler with a live to no10 and the neutral and earth to 2 and 3 .
    i do not have a cable from the boiler to the wiring centre to accomadate this, what can i do? (short of running one in )
    the boiler is an ideal classic 270 ff,programmer is a siemens RWB 29Si,wilo gold 15/60 set on 2,acl CH valve, Drayton dhw valve, honeywell cylinder stat and room stat
    Problem and reason for adaption?
    boiler was random firing when heat or dhw not required or asked for. as far as i can tell 5/6 times a day ,firing up for approx. 60 seconds. the 28mm pipe above the pump and the dhw valve always appear to be hot to touch, ch valve always cold, so i suspect this external control to be playing up. the original wiring centre was a group of mixed size connector blocks all shoved in a twin box and i bought a honeywell 10 way block to tidy it up but i am having a bit of bother re wiring it
    any advice please and thanks for putting up with the long post
     
  2. twgas

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    it's usual to have the wiring centre (junction box) in the airing cupboard next to the cylinder, valves and pump. All the wires ought to go to the wiring centre, it makes life much easier, especially for the not-so-competent.
    I'm a little confused with the wire to the boiler - where does it come from?
     
  3. kevindgas

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  4. terence7556

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    sorry tw did,nt make it clear the wiring centre is in the airing cupboard as expected.this is my problem, i have a supply from the fused spur to the w.c. but not one from the boiler to the w.c. taking the live conductor to no 10 in the w.c.
     
  5. D_Hailsham

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    OK, so far.

    Does this come straight from the fused spur? If which terminals does it connect to in the boiler

    That's probably the cause of your original problem.

    You need to find out exactly what the flex to the boiler is doing.
     
  6. terence7556

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    hi mr hailsham the flex is direct from the fused spur and the other end is the mains plug which connects to the rear r/h side of the p.c.b.
     
  7. terence7556

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    the phrase "mains plug " is from page 20 item 38 pictorial wiring in the m.i.s and the brown goes in and out of the o/h stat, then on to the on/off switch.the neutral goes direct to the on/off switch and the earth goes straight to the earth connection in the boiler.
     
  8. D_Hailsham

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    So the boiler will run 24/7, controlled by the boiler thermostat and the overheat thermostat. All the programmer, cylinder stat and wall stat are doing is to control when the motorized valves open and close.

    You need to run a 3 core cable from the wiring centre (L=10, N=2, E=3) to the L, N and E terminals on the boiler. Remove the short flex from spur to boiler completely.
     
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  9. terence7556

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    ok i will do that . much appreciated.
     
  10. bengasman

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    The best way to go about solving a problem with an obviously incorrectly wired up control system, is to strip it, and start again. It is a lot quicker and easier than trying to undo other people's eff ups.

    Bear in mind that the connections to the pump and the boiler should be heat-resistant flex.
     
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  11. matt1e

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    I totally agree
     
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  12. terence7556

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    thats what im doing. the original wiring centre was 6 or 7 connector blocks shoved into a double box3.... and i0 01a1m1231 041 3
    attemp ting t0o sort01 0out a random firing problem, possibly dhw valve/cyl stat and i decided to install a honeywell 10 way.did this, belled out to sort out whats whats and caused this. cable problem which dave has pointed out a solution to.all looks neater so part one sorted and ive learned a little bit so all good
    thanks guys
    ps my grandson is helping me type this154
     

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