Warmflow combi boiler HW not very hot

Discussion in 'Plumbers' Talk' started by Jamie Smith, Jan 4, 2019.

  1. Jamie Smith

    Jamie Smith New Member

    Good Evening Peeps.

    I have been having issues with my boiler this year, I got a split in my condensing tank (fixed) I then had to replace my faulty flow switch (fixed)
    Since all of this i have been unable to got consistent hot water from the boiler.
    CH water flow is fine (bubbles in system for like a minute to start with) advised not an issue, but CH works absolutely fine.

    but HW doesnt come out hot. The hot water in to the heat exchange is hot to touch, but the HW out isnt consistenly hot.
    The black valve above the exchange is on 5 - 6, i have my dial on the boiler controls set to full,
    My system pressure is set to 1.2bar and consistent.....

    Is it requiring a flush?

    Its a Warmflow combi oil boiler (external)
  2. Jamie Smith

    Jamie Smith New Member

    After investigating further due to the hot wwater being fine from sink taps, however from the bath which flows a larger volume the water is a lot cooler... however if i close the tap to half pressure the water gets hotter?
    Any ideas?
  3. dcox

    dcox Screwfix Select

    Your cold water passes through a heat exchanger in the boiler which heats it. When you use your hot sink tap the flow is slow enough for the water to absorb plenty of heat but when you use your hot bath taps it's flowing faster so not staying in the heat exchanger long enough to absorb all the heat. That's the reason but can't help with a solution without more info about flow rates and boiler rating.
  4. Heat

    Heat Screwfix Select

    Also got to check if hot connections are not blocked.
    The blending valve on some boilers could be partially blocked, limiting flow to bath.
  5. ChrisThomas1000

    ChrisThomas1000 New Member

    I have the same problem how did you overcome it
  6. heatyman

    heatyman Well-Known Member

    Scaled up DHW plate heat exchanger. Best replaced and fit a scale inhibitor.

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