Ideal Classic RS250 boiler

Discussion in 'Plumbing and Central Heating' started by dmb06851, 30 Jan 2007.

  1. dmb06851

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    We have recently moved house.

    When the thermostat in this boiler opens it kicks up a hell of a racket on radio and telephone (wired, not cordless.) If there is a suppressor fitted then it has obviously failed.

    Ideal's web site has installation instructions for a more recent boiler so the construction is a bit different.

    I would like to know the sequence of disassembly to the point where the connections on the thermostat are accessible so I can fit a new suppressor.
     
  2. Agile

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    Boiler thermostats dont normally have an RF supressor. ( Ya Ya ! Yes we all know the Baxi BBU does and some Ideals have a line supression filter ).

    You can always fit one yourself if its your boiler!

    These thermostats rely on a bistable moving contact to give a rapid snap action. If its not snappy like a crocodile then it should be renewed.

    Of course it sounds as if your radio may not have a very efficient antenna! Are you still listening on MF or LF by any chance? If so better change to VHF FM and take advantage of the relative immunity of the discriminator, pulse counting or phase locked loop demodulator to amplitude interference.

    Tony Glazier
     
  3. bster

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    darn.......i was just about to mention that! honest :D
     
  4. dmb06851

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    Thank you Tony.

    Did you overlook that I mentioned there is inteference on the (corded) 'phone too?

    An f.m. discriminator's immunity to amplitude variations is only realised when the receiver is fully, or nearly, quieted, i.e. when the discriminator is limiting.
     
  5. bster

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    you actually understood what he said :eek:


    when you say the stat kicks in and causes interferance can you explain in laymans terms? for no other reason than to educate me.
     
  6. dmb06851

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  7. kevplumb

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    its arcing cos the suppressor (capacitor) aint working


    i think :confused:
     
  8. dmb06851

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    Sorry bster, I overlooked your question.

    When a switch carrying current to an inductive load (in this case the gas valve's solenoid) opens arcing takes place across the opening contacts.

    This is a spark transmitter, similar to, but rather smaller than, that used by Marconi etc etc etc.
    A spark transmitter has a very broad bandwidth, i.e. it radiates energy on a very wide range of frequencies.

    The wiring to the contacts, as far as this arcing is concerned, is an antenna which radiates the damned interference!

    Connecting a suppressor, which usually is a small value capacitor in series with a small value resistor, across the contacts reduces the size of the arc and therefore the signal strength of the transmission.
     
  9. namsag

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    If memory serves me right for the old RS boilers .Drop the front cover.. on the underside of the boiler at the front just behind where the front cover top touches on each side is a little posi drive screw undo these and wiggle the bottom section of boiler off.. Your thermostat is held in a metal casing which is held in place with one screw into the underside of the main boiler casing undo this and it should allow you acces to stat.. You will not break any case seals doing this so no worries there. Can`t remember if this boiler was ever fitted with a suppresor though
     
  10. bster

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    dmb06851

    cheers - more understandable than that other language you and the 'Adge' were speaking in the beginning :D
     

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