where is the sludge :-s

Discussion in 'Plumbers' Talk' started by haveagobob12, Nov 28, 2022.

  1. haveagobob12

    haveagobob12 Member

    Hi there, after a bit of honest advice if i could.

    Have an open vented CH system with 11 rads on it. I have been getting cold spots to bottom area of 3 rads.

    Had a mag filter fitted & have been running x2 bottles of x400 running in the system but it doesnt seem to be helping.

    What I find though during the multiple times I have drained down 7 refilled. Is if i half fill the rads with the issue i can literally get the bottom half of the rad piping hot, but when i fully bleed it the top half then gets piping hot and the bottom half goes cold again... I am struggling to understand how right in the middle bit can be sludge or something stuck stopping the flow if I can get it heating on a half fill?

    I am trying to avoid taking the rads off & manually flushing them & wondering if there is another way to focus on this middle area of blockage?

    I considered trying x2 bottles of x800 or some MC5? But is it not just the same stuff?

    Looking forward to hearing any opinions/ideas?
     
    Robert Lee 1978 likes this.
  2. Mike83

    Mike83 Screwfix Select

    If the radiators heat when only half full then it’s probably not sludge.
    It could be a balancing issue or circulation problem.
     
  3. haveagobob12

    haveagobob12 Member

    Hi there, would that still be the case when I shut down all other rads via TRV & focus say on just one as I can still only get half of it to heat. I have a relatively new self bleeding pump set to highest speed, replaced air separator that was gunked up. Got me thinking now if I might have an issue with the 2 port valve as before it was making a vibrating noise but then stopped by itself.
     
  4. Mike83

    Mike83 Screwfix Select

    If the pump is pushing against only 1 radiator I would expect it to heat the complete panel. If not I would suspect sludge.
    But if you only half fill it and it heats up halfway this would indicate no sludge.
    Strange.
    What size are the pipes feeding the radiators?
    What type radiators do you have?
     
  5. haveagobob12

    haveagobob12 Member

    I have the Kudox single panel rads from screwfix being fed by microbore but with larger tails going into the rads to make it pretty on chrome :)
     
  6. haveagobob12

    haveagobob12 Member

    I have had the X400 in the system for nearly 4 weeks this weekend so I think I am going to dump it out. The mag each day when checking although is still getting some magnitite on it, its not riddled & I have had the heating on a lot over the last 4 weeks to try and get things moving.

    One weird/strange/god only knows thing I want to mention... a bit back when I was running x800, one rad up stairs which was behaving the same I foolishly whilst having the CH running & bleeding that rad had the bleed screw pop out on me... Anyway, you learn from your mistakes and swear whilst tidying up... anyway - after getting everything back online again that rad no longer has the problem & is hot all over...

    So I cant work out in that scenario how that helped clear an air lock in the rad bottom half or move some sludge? Just doesn't make sense?

    But I am wondering if I should do something similar on another rad after ive drained & refilled (apart from loosing the bleed screw) thinking of just bleeding it into a bucket for ages to try and get things moving? Even considered sticking a wet vac on the bleed valve to move things?

    Literally clutching at straws here to avoid removing the rads and or power flushing.
     

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