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Vaillant Hot Water Mode

Discussion in 'Plumbing and Central Heating' started by Simon_NoWH, 12 Jul 2021.

  1. Simon_NoWH

    Simon_NoWH

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    I have just bought a house with a Vaillant ecoTec 637. The previous owner had some terrible Honeywell system installed but took all the controllers. So I can’t control the system, and in particular I can’t get the hot water on, no matter what I do. I had previously used a tado system, so I have connected this to the eBus as instructed, but still no HW, even if I can now control central heating.

    Oddly the boiler doesn’t display the target hot water temp… it seems to be in a central heating only mode. What do I do? I have been through the installer mode for the boiler but I can’t find a setting. Some of the old wiring for the Honeywell evohome is still connected though I have disconnected the thermostat/bridge BDR91… HELP!!
    I have all i need for tado, which should work, but doesn’t.
     
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  3. CBW

    CBW

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    You need a programmer for the hot water, a cylinder thermostat and a zone valve to activate the boiler. Do you have these?
     
  4. Simon_NoWH

    Simon_NoWH

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    I don’t know. How do I tell?
    I imagine the whole thing was working fine before the old owners moved out?
    The boiler was controlled by a Honeywell evohome system. This was wired to a thermostat BDR91A1000 and a Potterton EP2 controller was attached, but the potterton didn’t seem to control anything - the boiler was on all the time irrespective of settings on the boiler. These are wired to a couple of relay controlled valves via a wiring loom.
     
  5. CBW

    CBW

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    So your Potterton EP2 is the programmer. Where the hot water cylinder is situated, there should be a small thermostat strapped in place with a wire - a bit like a net curtain wire. Wiring loom? Relays? The relays may bring your hot water on. Also if you’re in need, you may have an immersion heater. A couple of photos at this point might be best.

    Cylinder cupboard showing: cylinder, any valves and wiring.
     
    Last edited: 12 Jul 2021
  6. Simon_NoWH

    Simon_NoWH

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    I enclose some pictures below:

    52CB1A65-7D1A-4D57-87D1-13D7B150366E.jpeg 6C8A557F-7314-46CB-9E3B-DE7E884153BE.jpeg 84011A13-B87A-401C-9D93-C6FB1F0B07FF.jpeg AE17C2ED-D143-4905-8A30-3880B2FB9F3D.jpeg BB1A552F-07F4-4A12-A228-9F353633470A.jpeg 59457689-B85E-4AE8-BDE3-7434B27E24C1.jpeg 185CCF1C-C722-4DF6-86C3-DCDDAECB647E.jpeg 51C0057B-087D-43D0-A551-2C7D1881D54D.jpeg 6ABB4EDF-125F-4D6B-98E8-E027A4C195A1.jpeg B12CE18D-3BFE-4F9F-9198-F2D927BF0790.jpeg
     
  7. Simon_NoWH

    Simon_NoWH

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    The potterton unit is no longer attached. This has been replaced by a tado extension attached to the + and - terminals of the eBus as instructed by tado.
     
  8. Simon_NoWH

    Simon_NoWH

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