Vertical radiator cool at bottom

Discussion in 'Plumbers' Talk' started by BrianL55, Nov 29, 2019.

  1. BrianL55

    BrianL55 New Member

    I've swapped my existing kitchen radiator, a Radson Type 22, 600mm x 600mm, 1099 Watts with a Milano Alpha, 1780mm x 280mm 1099 Watts vertical and I’m pretty disappointed in its heating performance – so far.

    There is a significant fall of in temperature between the top and the bottom with the top being as hot as the pipes but the bottom is significantly cooler.

    Do I have a dodgy radiator or do I have to restrict the outflow valve to slow the flow down?

    Thanks in advance.
  2. andy48

    andy48 Screwfix Select

    If flow and return are at the bottom, did you fit a baffle as stated by the installation instructions? Have a look at bestheating DRVFD15
  3. BrianL55

    BrianL55 New Member

    Thanks for that info, I will have to ask the plumber but I don't think one was fitted.
  4. DIY0001

    DIY0001 Active Member

    Are all 4 of the panels showing the same temperature drop from top to bottom?

    Are the inlet & outlet at the bottom of the radiator or is one of them at the top?

    Although the Milano instructions recommend fitting a baffle, the two that I have previously fitted came with the baffle already installed, causing much confusion. So I wouldn't be too concerned if you didn't see the plumber specifically fitting one. The baffle is intended to force the water to flow through the radiator panels rather than just going directly from the inlet to the outlet. Depending on the in/out positions it may not be needed.

    Start by turning the valve and lock shield off and letting the radiator cool down completely. Then open both valves and feel where the hot water is flowing through the radiator panels. You should feel the heat at the inlet pipe first, then through the panels to the outlet pipe. If it is just going directly from inlet to outlet without flowing through the panels and heating them up, then the baffle is needed, but missing.
    The Teach likes this.
  5. The Teach

    The Teach Screwfix Select

    Some of the vertical designer items (uk radiator in name only) will be much colder where it exits and returns to the heat source to be reheated.

    As long as the new heat emitter is fitted correctly,then the existing heating system needs some fine tuning to get a more even heat distribution usually thermometers are used to check how well the radiators are actually working.

    BrianL55 do you know who manufactures your new vertical designer item ?
  6. BrianL55

    BrianL55 New Member

    Inlet is bottom left.
    Outlet is bottom right.
    Inlet pipe heats up first.
    Radiator heats up first at top left.
    All 8 (4 x 2) panels heat up the same, hot at top cooler at bottom.
  7. BrianL55

    BrianL55 New Member

    Milano is exclusive to Bestheating in the UK, don't know who the actual manufacturer is.
  8. Heat

    Heat Screwfix Select

    Turn other radiators off and if your new radiator has improved performance, then it hasn’t enough flow through it. Designer/vertical rads are generally more restrictive for flow, compared with ordinary rads.
    Balancing system would help if rad improved with others off.
    Another point - does it have a TRV (thermostatic valve) on it? Normal TRVs restrict flow
  9. DIY0001

    DIY0001 Active Member

    So the hot water is coming in bottom left and flowing up the left panels to the top, as it should. It then can't get out unless it flows down the right panels to the outlet on the right. While doing that, it loses heat to the room, which is just what it is supposed to do. With vertical radiators the bottom outlet will always be a bit cooler than the top.

    Is the bottom right actually cold, say compared to the radiator was when the valves were turned off? If it is then you probably need more flow, so open the lock shield a bit more.

    It sounds like you may just have optimum flow, or a TRV ensuring that the flow is just enough to keep the room at the set temperature. It is a common misconception that radiators should be hot. When properly balanced they should just slightly warmer than the temperature you want the room to be at.
  10. Jimbo

    Jimbo Screwfix Select

    Check if the outlet pipe is hot or cold, compared to the outlet of other radiators.

    If it’s cold, the flow should be increased by fully opening the valves and adjusting the lock shield valve of all other radiators down a quarter of a turn. Wait 20 minutes and re test.

    if it’s hot, the flow is too fast and the lock shield in the new radiator should be closed a little until it starts to feel a little less hot and the radiator surface hopefully more even.

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