Red expansion vessel - pressure too high

Discussion in 'Plumbers' Talk' started by Mike2021, Oct 12, 2021.

  1. Mike2021

    Mike2021 New Member

    Hey

    Ive noticed that the red expansion vessel in my system is at 2bar when cold, when the red needle says it needs to be 1 bar. I've only noticed thewe recently after switching the water off and on when a tap needed replacing. Though now that im thinking about it, I dont think the water that goes to my megaflo is also the one going to my boiler although the red expansion vessel is linked to my megaflo even though I don't believe it's for my water and is in fact for my heating.

    How can I get my pressure back down to 1 bar and could the turning off and on of the water supply have messed it up?
     
  2. terrymac

    terrymac Screwfix Select

    Drain some water from a radiator or a drain cock.
    Turning water supply off to taps will not affect the sealed c/heating systems pressure.
     
  3. Mike2021

    Mike2021 New Member

    Thanks, will I see it drop in real time ? Obviously don't want to let too much out
     
  4. terrymac

    terrymac Screwfix Select

    Pretty much right away.
     
  5. Mike2021

    Mike2021 New Member

    Brill I'll give that a go. What could cause the pressure to go up without me interfering with the system ?
     
  6. terrymac

    terrymac Screwfix Select

    Filling loop open would increase pressure. Central heating in operation increases pressure and when its off and cooled ,pressure drops back to what it was. Another possibility is the coil pin holed ,and the mains pressure water would enter the sealed system.
     
  7. Mike2021

    Mike2021 New Member

    Thanks for that. I'll keep an eye on it and see if it creeps back up when cold.
     
  8. dcox

    dcox Screwfix Select

    Are we talking about a boiler here? Sounds like it could be an invented cylinder.
     
  9. Mike2021

    Mike2021 New Member

    I do have an unvented cylinder. I did let some water out of the radiator and the pressure did start going down.
     

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