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grant combi 90 - hot water - cold

Discussion in 'Plumbing and Central Heating' started by Robdiy48, 14 Dec 2019.

  1. Robdiy48

    Robdiy48

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    Hi , I'll try and answer as much as I can
    CH fine -
    changed 3 way valve 2 year ago, changed pump around year ago along with air vent and recent PRV.

    HW flow always been low, pulled of the Flow valve & the CW in filter was blocked, a little scale inside bottom of the valve itself, valve seems to be moving when turning, put back on and still no HW but loads more pressure.
    3 way valve pin out after HW turned on. so believe the valve is fine

    Heat ex below the 3 way valve is luke warm to touch, front pipe from boiler is hot.

    Would this be the Heat Exchanger ? do I need to pull that off and give it a flush? or replace,or something I have missed.

    No other areas have been changed.

    thanks in advance
     
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  3. Robdiy48

    Robdiy48

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    Grant Combi 90 MKII
     
  4. Terrywookfit

    Terrywookfit

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    Is the divertor operating the microswitches.
     
  5. oilhead

    oilhead

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    On Hot water only, does the burner fire when there is a demand?
    Is the heatstore hot?
     
  6. Robdiy48

    Robdiy48

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    Divertor valve is operating micro switch

    Boiler fires up when HW demand
     
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  8. Robdiy48

    Robdiy48

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    Heat store is hot, pipe from there to Heat ex is hot - Heat ex is warm.

    Update:
    CH is on - Pipe into Heat Ex is hot, Heat Ex is Hot pipe to Mixer Valve is hot - water out of mixer valve is cold

    Possible mixer valve ?
     
  9. Robdiy48

    Robdiy48

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    mixer valve = Blending Valve
     
  10. Terrywookfit

    Terrywookfit

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    If the hot to TMV hot then TMV is faulty
     
  11. Robdiy48

    Robdiy48

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    TMV.. will replace this,

    Keep you posted and thanks
     
  12. DIYnot Local

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