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Discuss New rads fitted 4 weeks later one needing bled in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. Robert Anderson

    Robert Anderson Member

    morning guys just looking for some advice I think the answer is hopefully straight forward however just double checking got 3 new rads fitted a just over a month ago however one had a small leak which got sorted a 3-4 weeks ago last night I noticed one of upstairs rads had a slight cold patch not stone cold anyway when heating went off I bled it and it had a decent amount of air about 5-6 second of ffffffsssssing lol and the other 2 upstairs had a tiny bit over alldropping about 0.2-3bar am I correct I’m assuming this will be just air that’s settled at the highest point from refilling after the fitting and then the repair?
     
  2. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    It should be yes. Did you make sure that you topped the pressure back up?
     
  3. Robert Anderson

    Robert Anderson Member

    Yeh just did that this morning as waited to the system was fully cold n topped it back up to 1.5 bar that’s what it was prior to bleeding I just got a bit worried as I googled it n you start getting all this stuff about corrosion gasses building up etc as opposed to just air gathered due to refilling and started to worry it was something like that lol even tho the old radiators didn’t need bled at all and were about 25 years old, I thought it was just the air bubbles collecting in one area but just wanted to get a expert opinion it wasn’t cold as such just a patch on top left of rad was cooler but still pretty warm the rest of the rad was roasting. heating on just now after topping up
     
  4. Robert Anderson

    Robert Anderson Member

    Also I know us non experts shouldn’t google these things lol bit like googling sore foot and then you have a terminal illness!! Thanks for the reply btw
     
    • Funny Funny x 1
  5. scott_d

    scott_d Plumber GSR Top Contributor!!

    Its normal for some air to work it's way to the top of the rads after a drain and refill
     
    • Like Like x 2
    • Agree Agree x 1
  6. fixitflav

    fixitflav Member

    Was inhibitor topped up when the rads were added? If not you should add some. Next time you bleed, check to see if the gas coming out will burn. If it does it's the result of corrosion and needs more inhibitor. Also you could take a sample of the water, add some bright wire nails. If they go rusty after a few days more inhibitor needed.
     
    • Like Like x 1
  7. Robert Anderson

    Robert Anderson Member

    Would it take a few weeks for that to work it’s way to the top also I’m assuming if the old rads never needed bled then corosdion gasses isn’t the problem
     
  8. fixitflav

    fixitflav Member

    You probably lost some system water when the new rads were fitted, and more fresh water will have gone in. So no corrosion gases before doesn't mean there isn't now.
     
  9. Chuck

    Chuck Active Member

    I think this advice is dangerous. The information is of little value and there is a significant risk burning yourself and/or causing a fire. I've seen several cases where the person trying it didn't realise that hydrogen flames are (nearly) invisible and burned themselves quite badly.

    Not necessarily. It is normal for new radiators and pipework to evolve hydrogen for weeks, if not months, after installation while the passivating layer forms. Inhibitor doesn't stop this process, it just happens a bit slower (completes in months rather than weeks).

    This test needs two separate samples of water in sealed containers. One from the heating system and one from the kitchen tap to act as a control.
     
    • Like Like x 1
    Last edited: Nov 8, 2018
  10. Robert Anderson

    Robert Anderson Member

    Ok thanks everyone seems a bit more complex than I had hoped I was hoping it may just be air from refil??
     
  11. Robert Anderson

    Robert Anderson Member

    Also if it was gasses how long would it take them to build up again so how long roughly would the rad need bled again you talking weeks or months I’m not sure I want to continually spend the winter touching radiators lol
     
  12. Chuck

    Chuck Active Member

    It probably is just residual air. It could also be hydrogen from the new radiators/pipework forming a 'passivating layer'. As long as you are sure some inhibitor was added when the system was refilled you shouldn't worry at this point. Just touch the radiator where the air/hydrogen is collecting once a week and bleed it if it's cold along the top. It will probably slow down after a week and have stopped completely after six months.

    5 seconds of ffffffsssssing through pinhole bleed-point is a tiny amount of gas. Nothing to worry about.
     
    • Like Like x 1
  13. Robert Anderson

    Robert Anderson Member

    Perfect thanks it’s just a hassle I don’t really need as most folk don’t lol and I get a bit ocd with this type of thing so I appreciate everyone’s help and reassurance my mates/neighbour is a heating engineer has been for a while he fitted the rads n said last night it would just be settlement air as we had to refil couple of times to get the repair done which was a olive at a jaunty angle lol anyway just thought I would ask the forum too and as always very helpful cheers guys have a great day
     
  14. Riley

    Riley Plumber GSR Top Contributor!!

    Really wouldn’t suggest trying this as it’s dangerous
     
    • Like Like x 1
  15. Robert Anderson

    Robert Anderson Member

    Yeh I’m not sure I want to start fires from gasses in my house to be honest unless it’s my hob
     
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