1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

"Gas" in Radiators

Discussion in 'Plumbing and Central Heating' started by Godrup, 8 Jan 2020.

  1. Godrup

    Godrup

    Joined:
    13 Jan 2016
    Messages:
    20
    Thanks Received:
    1
    Country:
    United Kingdom
    Thanks, I captured some of the gas in an old beer bottle when bleeding this afternoon, and there was a definate "whoosh" (not a pop) when I stuck a long lighter into the neck. I'm going to do it again tomorrow just to be sure.

    Ps; yes, I've bled the pump too. If the gas ignites or pops tomorrow, I'll drain the whole system, flush and stick in inhibitor and see how that goes.
    Also, when the heating is on the radiators seem ok and dont need bled, theres always air or "gas' in the radiators when left overnight?
     
    Last edited: 10 Jan 2020
  2. Sponsored Links
  3. ScottishGasMan

    ScottishGasMan

    Joined:
    22 Jan 2007
    Messages:
    6,189
    Thanks Received:
    2,107
    Country:
    United Kingdom
    Make sure you use good inhibitor not cheap trade stuff.

    Stick to fernox or sentinel, ideally for gassing issues fernox MB1 used to be the best for it, but any good stuff should do the job once the systems been cleaned out.

    Bear in mind after draining and flushing out a few times and refilling, it may take a few days depending on your system, to get all the air into the rads and vented out, so dont me too surprised if you do still have to bleed them over a short period after
     
    • Thanks Thanks x 1
  4. Godrup

    Godrup

    Joined:
    13 Jan 2016
    Messages:
    20
    Thanks Received:
    1
    Country:
    United Kingdom

    Good advice thanks SGM.

    Well I did the bottle trick with the gas out the radiator, which I'd left over night & it did "pop", so i think it's quite conclusive that it's a build up of Hydrogen gas overnight due to excessive corrosion products in the water/radiators.

    I've drained & flushed the system, and also removed & flushed a few radiators that are older. Suffice to say, the water coming out the drain was pretty bad. Last time the system water was changed was 2018. I think I'll need to do this annually.

    System is now refilled with Fernox MB1, and the radiators seem to be much hotter than before. I'll monitor it and update once the system has settled down.

    What is clear; if the system is sufficiently contaminated, it can produce enough hydrogen gas overnight to cause a radiator airlock.
     
    • Like Like x 1
  5. Madrab

    Madrab

    Joined:
    4 Oct 2012
    Messages:
    5,658
    Thanks Received:
    1,434
    Location:
    East Renfrewshire
    Country:
    United Kingdom
    Buy some litmus paper .... do a test on the system water .... anything quite alkaline > 9 - 10 (dark green to blue) then it can cause corrosion with an aluminium HEX and create hydrogen in the system.

    In effect it will eat the HEX from the inside.
     
    • Thanks Thanks x 1
  6. Godrup

    Godrup

    Joined:
    13 Jan 2016
    Messages:
    20
    Thanks Received:
    1
    Country:
    United Kingdom
    Thanks, I'll run it for a couple of weeks then check water.
     
  7. Sponsored Links
  8. Lower

    Lower

    Joined:
    22 Dec 2005
    Messages:
    1,164
    Thanks Received:
    116
    Location:
    Leicestershire
    Country:
    United Kingdom
    Don’t drain it every year. Flush it to the point the water is coming out clear, put the inhibitor in to get the corrosion under control and then leave it.

    if it’s not pumping over and you’ve got a magna clean, you shouldn’t drain it and refill it annually as you introduce fresh oxygenated water into the system every time which just causes more corrosion.
     
    • Thanks Thanks x 1
  9. Godrup

    Godrup

    Joined:
    13 Jan 2016
    Messages:
    20
    Thanks Received:
    1
    Country:
    United Kingdom
    Thanks, and yes valid point, I did that 2 years ago, however the water in the whole system was pretty black this time.
     
  10. Godrup

    Godrup

    Joined:
    13 Jan 2016
    Messages:
    20
    Thanks Received:
    1
    Country:
    United Kingdom
    I thought I'd update this for completeness.

    So system drained, flushed and refilled with MB1 inhibitor. Few days of settling in and bleeding etc. So over a week later and the system doesnt need bleed at all, and the offending towel radiators dont need bled either. I also think the automatic valves are working now too.

    So it was in fact hydrogen gas being generated at an alarming rate - my fault for not draining and dosing the system.

    Thanks to all on here for advice and help
     
    Last edited: 20 Jan 2020
    • Thanks Thanks x 1
  11. Mottie

    Mottie

    Joined:
    27 Feb 2017
    Messages:
    4,723
    Thanks Received:
    534
    Location:
    Essexshire
    Country:
    United Kingdom
    What should the litmus paper reading be for a boiler with an aluminium HEX?
     
  12. Madrab

    Madrab

    Joined:
    4 Oct 2012
    Messages:
    5,658
    Thanks Received:
    1,434
    Location:
    East Renfrewshire
    Country:
    United Kingdom
    The litmus should be as close to neutral (7 - olive) as possible, CH water especially if it hasn't been flushed properly, will tend to be more alkaline. The more alkaline it is the more reactive it will be with aluminium to create hydrogen.
     
Sponsored Links
Loading...

Share This Page