Upstairs heating issues...

Discussion in 'Getting Started FAQ' started by marliechiller, Nov 20, 2023.

  1. marliechiller

    marliechiller New Member


    I have recently moved into a 3 story terraced house built in 2011. When I moved in, the house utilised a danfoss heating system that I wasnt familiar with. Inside the airing cupboard (which is situated on the top floor) was a danfoss FP715 Si 2 channel programmer for heating and hot water. On the wall outside of the airing cupboard was a TP5000 Si thermostat. On the ground floor there is a simple danfoss dial to set the temperature. This setup seemed to work ok heating the house and controlling the hot water.

    My problems arose when I decided I wanted to upgrade from a fixed programmer to a newer app controlled system. I removed the FP715 inside the airing cupboard and replaced it with a drayton wiser (kit 2), whilst also removing the batteries from the TP5000 and capping its electrical cables with electrical tape to render the thermostat inert. Both the drayton wiser and the original danfoss FP715 both seemingly had the exact same terminal connections so I thought this would be a straight sway. Once I made this change however, I lost the ability to control the heating to the upstairs of the property. The hot water and downstairs heating continued to work fine. Eventually, I realised that the airing cupboard contains 2 danfoss HPA2 valves. Im guessing 1 controls the upstairs and 1 controls the downstairs as when I engage the manual override on one of these, the upstairs heating magically works.

    My query is essentially 2 fold:
    1) can a drayton wiser smart programmer work in the system I described? The original programmer seems to suggest that the property is a 2 channel system (channel 1 central heating, channel 2 hot water), however if there are 2 HPA2 valves, doesnt this suggest a 3 channel system?
    2) if it is only a 2 channel system (which I hope is the case), how can I get the drayton wiser to open up the second HPA2 valve automatically? Ive read that these automatic valves fail sometimes and need replacing but before I do that, I want confirmation that its likely broken and simply replacing it will fix the problem.

    I have attached a picture of my airing cupboard in case that offers any insight into my system.

    Thanks for your input in advance!

    Attached Files:

  2. Tricky Dicky

    Tricky Dicky Screwfix Select

    I'm only DIY, and no doubt a plumbing expert could confirm, but you appear to have 3 motorised valves, upstairs & downstairs heating and domestic hot water, 2 room thermostats, one adjacent to the airing cupboard and one ground floor. I think you have made some wiring errors when installing the App controlled system.
    If there a wiring control box, that might clarify the circuits?
  3. marliechiller

    marliechiller New Member

    Yes, youre right. There is a third motorised valve which I hadnt realised which must control the hot water. I didnt modify any of the existing wiring connections as the new programmer had the same wiring connections as the old one. It does seem like there might be 3 channels though if there are two thermostats. What is confusing though is the original programmer is clearly listed as a 2 channel programmer. Ive attached the wiring diagrams of the two systems just to confirm im reading them both correctly. (Old and new respectively. Im using the middle 2 channel diagram for the new programmer)



    Attached Files:

  4. Tricky Dicky

    Tricky Dicky Screwfix Select

    Do you an actual photo of the original wiring of the programmer? Where there any other wires being used?
  5. marliechiller

    marliechiller New Member

    Heres the base plate wiring under the programmer (untouched as mentioned)

    Attached Files:

  6. The Happy Builder

    The Happy Builder Screwfix Select

  7. marliechiller

    marliechiller New Member

    @The Happy Builder im guessing I would need to do significant rewiring if that were the case given the current base plate configuration?
  8. marliechiller

    marliechiller New Member

    Its also not clear to me how the original 2 channel danfoss system was able to heat all of the house (i.e 3 channels) if that is the case

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