introduce Honeywell BDR91A Relay to Potterton EP2002 timer

Discussion in 'Plumbing and Central Heating' started by Blueandy197, 31 Oct 2010.

  1. Blueandy197

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    Hi there,

    My Alpha boiler in the loft has no internal timer clock or room thermostat connected. The timer is an upstairs bedroom and I have bought a DT92E Wireless Room Thermostat for downstairs.

    Please could someone help me with the wiring configueration so these will work together.

    Potterton is currently connected:
    Mains: Blue N & Brown L

    To boiler: Blue N & Brown L, Black 2 & 4 and Red jumper between L & 5. It also has open connections available for A,B,C,D.

    The BDR91A Relay has open connections for NLL and ABC.

    Your help will be truly appreciated.

    Many thanks,
    Andy
     
  2. D_Hailsham

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    I can understand the black from 4 to the boiler as that is CH ON, but normally 2 is not used as that is CH OFF.

    Can you check this please. If it is there, can you find what it connects to at the boiler (boiler details will be helpful as well).
     
  3. Blueandy197

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    Thanks for taking an interest!

    It'a an Alpha Combi Boiler CB28.

    The Potterton timer has black in both 2 & 4, but 1 & 3 are empty.

    Up at the boiler both black go in to 1 & 2 of a connection block marked 'room thermostat' and lead out as two red wires that diappear in to the main housing.

    On the back of the housing there is a wiring diagram that says 'remove link to connect external control to connect switched live to no. 1 terminal', connect external control to terminals 1 & 2.

    Cheers
    Andy
     
  4. D_Hailsham

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    Whoever wired it up originally did not know what they are doing.

    1 & 3 empty is OK because they are the HW terminals which are not required as you have a combi.

    A wires is needed in terminal 4 as it is the Heating ON terminal, but a wire is not needed in terminal 2. Did the boiler run continuously?

    The Relay box needs to be wired as follows:

    Connect one L and N to a permanent mains supply, e.g the L and N terminals of the EP2002.

    Remove link between L and 5 on EP2002
    Connect EP2002 terminal 4 to Relay Terminal A
    Connect Relay terminal B to boiler terminal 1.
    Connect EP2002 terminal 5 to boiler terminal 2
     
  5. Blueandy197

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    Ex-girlfriends 2nd cousin was a gas fitter?

    Thank you so much for your post I hope to try this tonight.

    Andy
     
  6. D_Hailsham

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    Some gas fitters are either not qualified for or do not understand the electrical side of heating and hot water systems. So they employ an electrician, who may be qualified but also does not understand.
     
  7. matt1e

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    never a truer word said Mr H
     
  8. Blueandy197

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    Evening guys,

    I've re-wired per your advice and have the wireless room stat talking to the relay, but cannot get the boiler to fire up even on override to CH constant.

    Any thoughts?

    Thank you
    Andy
     
  9. D_Hailsham

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    Try swapping the wires to boiler 1 and 2.

    If that does not work, do you have a multimeter? If so check the voltage at between boiler terminal 1 and N and between 2 and N. One of them should be 240Vac, even when the relay is off; the other when the relay is on.
     
  10. Blueandy197

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    I did swap the wires over, but will check the weekend with a multimeter as my dad has mine and will let you know it that's okay.

    Out of interest what is Terminal 5 for?

    Have a great week
    Andy
     
  11. D_Hailsham

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    It's the common for the heating switch. When CH is ON, 5 connects to 4; when CH is OFF, 5 connects to 2.

    5 get its supply from boiler terminal 2 (which should be permanent 240Vac). When the timer turns CH ON, 5 connects to 4, which is connected to Relay terminal A. When the relay closes, A connects to B, which is connected to boiler Terminal 1, the switched live terminal.
     
  12. Blueandy197

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    Evening, I've been up in the loft with my multimeter and boiler terminal 2 was 240v and terminal 1 was 0v when I then went downstairs to re-wire the EP2002 as I had took everything out last night.

    After re-wiring I still could not get it to work and now even more at a loss as on the EP terminal 5 connected to boiler T2 is 0v and Relay terminal B connected boiler T1 is 110v.

    I went back in to the loft T1 is indeed now 110v and T2 still 240v.

    Nothing changed when I flicked the Relay on/off.

    Any ideas?

    Kind regards,
    Andy
     
  13. D_Hailsham

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    That's correct: 2 is the supply and 1 the switched live.

    Then EP T5 cannot be connected to boiler T2.

    Are you using the pair of black wires to connect the boiler to the relay? If so,try swapping them over at both ends to see if the other one gives 240v on 5. If it does the other wire must be broken. If it is, there is a way round it, as follows:

    Connect one L and N to a permanent mains supply, e.g the L and N terminals of the EP2002. Already done

    Replace link between L and 5 on EP2002 New
    Connect EP2002 terminal 4 to Relay Terminal A Already done
    Connect Relay terminal B to boiler terminal 1. Use the "good" wire

    There is no need now for the wire from Boiler T2 to 5.
     
  14. Blueandy197

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    It works, it works, it works. Thank you so much, they say winter is coming next week!

    I was using the two black wires originally as you said and had swapped them over every which way. Tonight I used your work around, but picked up the one of the black wires at random at the wiring centre as couldn't remember where I'd left them at the boiler last night T1 or T2.

    So I replaced the link between L and 5 and first time lucky.

    For future reference what just happened and what is the difference in this configueration that wouldn't/shouldn't be as the initial we first tried as the preferred method - are they both just as okay?

    Again you are genius!

    Andy
     
  15. DP

    DP

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    Perhaps I am missing a vital piece of information here.

    Boiler is a combi wired to a potterton timer that is to be replaced with a honeywell wireless programmer.

    Why not remove the potty programmer, wire the live and neutral to L and N, and two blacks to A and B?

    Did I also see a note that live needs to be taken to the relay contacts? The switching is better left as voltage free (always unless otherwise stated) as parts of circuit would be live when boiler switched off at the facia controls
     

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