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Discuss Conventional boiler - Water is not hot enough in the Central Heating Forum area at

  1. DaniQ

    DaniQ New Member

    I moved in a house with a Vaillant Thermocompact 620e boiler with an insulated hot water cylinder.

    The heating works OK but the water for the bath and taps doesn't get hot enough. I have the hot water "wheel" turned to the maximum and i get water at 35C after having the boiler on for 4 hours

    Is there any way to increase the temperature to something like 50C?

    Thank you.
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    What does the cylinder stat read ?
  3. DaniQ

    DaniQ New Member

  4. jtsplumbing

    jtsplumbing Plumber GSR

    What temp is boilerr stat set to ? what is cylinder stat set to ? could be a number of things , Fault with boiler stat, or something else with boiler, Faulty cylinder stat, or 3 way valve faulty,
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    The box with the white band around the cylinder

    What's that set to
  6. DaniQ

    DaniQ New Member

    Is the boiler stat the grey thing on the left of the cylinder or the white smaller box attached to the cylinder?
  7. DaniQ

    DaniQ New Member

  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    That should be on 60

    And no that's the port valve grey box with 3 pipes connected

    Pic of your boiler with the flap down please
  9. DaniQ

    DaniQ New Member

    1502124403013.jpg Which position the 3 way valve should be set to? W M H?
    Last edited: Aug 7, 2017
  10. Stigster

    Stigster Plumber

    You don't set that. That's an indicator to show what position the valve is in at any given time. Water/Mid position (both on)/Heating. It's open to the hot water side in that pic.
  11. clemda1

    clemda1 GSR

    Could be one of three things? 1) the programmer, 2) cylinder stat or 3) 3 port valve. Simple tests you can do:
    Set cylinder stat to 60deg
    Set programmer to hot water only
    Confirm the boiler fires (assuming the pumps is working ok as you said the heating is ok)
    Now on the diverted valve feel the pipe going to the cylinder (cylinder flow pipe) this should pretty soon star getting very hot ( to hot to touch) and should stay hot until the cylinder reaches temperature (60eg)
    If not report back as to what in the above sequence did not happen and we can help further.
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