Could it be sludge ?

Discussion in 'Plumbers' Talk' started by Kas-fearless, Dec 22, 2017.

  1. Kas-fearless

    Kas-fearless New Member

    So during the summer I drained down my gravity fed heating system to do some work on it. Installed a slightly smaller radiator so I moved a leg. I cleaned the system with x800 and refiled with an inhibitor after draining and refilling with water. Now during the winter I realised that with the downstairs radiators the flows are hot but returns cold.

    To try and combat this I balanced the system but no luck. I have also just brought and installed a new grundfos alpha 2 pump but the problem remains.

    I suspect a blockage and only just have realised why this might be the case. The kitchen radiator contains the only drain off valve located downstairs. However the 3 radiators that are not working do not contain a drain off valve and are on a separate loop downstairs. So I suspect when I used the sentinel x800 it moved all the sludge from upstairs to the downstairs radiators. But when I was draining the water because the drain off is on a different loop I didn't actually remove the sludge. I suspect it is still stuck and causing the issue.

    Just wondering would this potentially be the issue ? I have tried everything else.
  2. KIAB

    KIAB Well-Known Member

    Could have drawn crud from the F/E tanks, wet n dry vac great tool for cleaning these out.

    Do you have a magnetic filter on system, if not first thing I do is fit one (Magnaclean Pro 2 highly recommended).

    Totally pointless putting X800 or any other cleaner in system, if you have no means to collect the crud that is dislodge by cleaner, all your doing is moving it around the system to cause more problems.

    Also need to fit a couple more drain cocks on system, easy enough to use garden hose & tap connector attached to lockshield to drain down.

    I would turn off all other radiators & work on the three problems radiator one at a time, trv & lockshield off,then remove radiator & take outside & flush though with hose, secondly I would get a bucket & open lockshield might disldge any crud.

    And heating off.
    Last edited: Dec 22, 2017
  3. Kas-fearless

    Kas-fearless New Member

    Oh yes sorry forget to mention I do have a fernox omega fitted. I agree that that it just pushes the crud around the system. I guess thats what I must have done. And since I didn't drain that loop off the crud is still there

    Plan is to add a drain off on that loop and cut into the tee where it converts from 22mm to 15mm and see if I have a blockage on the return as I suspect thats where it will be.
  4. KIAB

    KIAB Well-Known Member

    Not too familar with the Fernox Omega TF1 filter & how effective it is, alway have used the Magnaclean myself,as you can easily add a cleaner/ inhibtor into the canister, making it one of the best on he market,have you checked your filter & see how much crud you have collected.

    Last edited: Dec 22, 2017
  5. Devil's Advocate

    Devil's Advocate Well-Known Member

    How much did the Omega collect when you had cleaner in the system?

    That should give you an idea of the condition of your pipework.
  6. Devil's Advocate

    Devil's Advocate Well-Known Member

    You can buy a brand new 'Magnacleanse' (this is the proper flushing unit - two large cylinders) complete with hoses and fittings for £250 on t'Bay right now (tho' there might be postage on top...)

    After you've used it and cleaned it all up, you should get £250 back on it.

    If you have sludge - tho' it could also be an air lock, I guess - then your wee Omega (or even a Magna 'Pro') is unlikely to sort it. But if you were to plumb in the M'cleanse and run it with Adey MX whatsit for a few weeks, there's a very good chance it will.

    Meanwhile, how to shift a slug of sludge? I guess this thing to try is to shut off both valves to a dodgy rad, drain the rad and remove, take it outside and hose it through, giving it some whallops along the centre-bottom in the process. Note what comes out of it - that will be another good indication of pipe state.

    Then get someone to stand by the top-up tap so's to keep the pressure hovering between one and two bar as much as possible, stick a low tray/saucepan - or better still the correct fitting with a hose attached - and open one rad valve fully. The pipe to that valve - regardless of whether it's a flow or return pipe - should be trying to deliver the water at a goodly 1 to 2 bar, so quite a powerful force. If that doesn't shift what's in the pipe, then you have problems...

    Forgot to mention - have the other end of the hose outside.

    In a bucket so's you can monitor what's coming out.

    Repeat with the other end.

    The result of this should indicate what the issue is. If water comes out easily and there's little sludge, then it probably wasn't a blockage.

    Oh, and record exactly how far open the lockshield valve is before you shut it off so's you can return it to the same position...
  7. KIAB

    KIAB Well-Known Member

    Adey MC5 ,MC3+ or Sentinel X400 cleaner, leave it in for a few weeks.

    Never been impressed with the Fernox Omega TF1 & it's effectiveness as a filter, replaced one for a friend with a Magnaclean Pro 2 & was surprised how much more crud it had collected.

    Heving a Magnaclean Pro 2, making connceting a Magnacleanse to system for a few weeks so much easier.
    Will easily recoup theepense of buying one, when you come to resell it.
    Last edited: Dec 22, 2017
  8. terrymac

    terrymac Active Member

    Dev Ad , he has a gravity fed system , no filling loop . Kas ,have you tried turning off trv valves on all rads that work ,and see if cold Rads heat up. Do the cold rads one at a time ,with all trvs closed on other cold rads as well as the hot ones.failing this do as Dev Ad suggests take Rad off and flush pipes via the rad valves.
    Devil's Advocate likes this.
  9. Devil's Advocate

    Devil's Advocate Well-Known Member


    Got mixed up with another thread where the person mentioned system pressure :(

    In which case an air lock is more likely as an alternative cause, but opening a rad valve is less likely to shift a slug of sludge if that's the cause.
  10. terrymac

    terrymac Active Member

    Maybe dev ad , but still worth a go.
  11. Kas-fearless

    Kas-fearless New Member

    Yes tried turning off the locksheild valves on all other radiators but it doesnt make a difference. The fernox omega hardly collected any sludge. I have acces to the 22mm pipes that feed into this loop and I can feel that the flow is hot but the result is warm. So I suspect a blockage. But its puzzling me as two of the radiators are brand new. The loop used to work last summer. All I did was reduce the length of one leg. Never had a problem with sludge before though.
  12. KIAB

    KIAB Well-Known Member

    How old is system, if you drained down to add radiators, then highly likely you have dislodged some crud.

    As I said earlier I've never been impress with Fernox filter for crud collection.
  13. Kas-fearless

    Kas-fearless New Member

    I'm guessing around 30 years old although the boiler and cylinder has been replaced in the last 5 years. Yes I have to say I was expecting more from it. Guess I'll need to cut into the pipes and see what I find
  14. KIAB

    KIAB Well-Known Member

    Here is a Magnaclean Pro 2 filter with 12 months of crud on it.

  15. Kas-fearless

    Kas-fearless New Member

    Currently looking to get the blockage if any removed first and then install another filter. As I have access to the 15mm flow and return piping for the 3 radiators which do not work I was planning to push mains pressure water though the flow and see what comes out the return once I drained the system and have cut into the pipes. Only problem is I dont know how to connect the pipes to it. Currently only option is to solder two drain off valves and connect the garden hose to them.

    Anyone know of any clever ways to connect a garden hose to a 15mm copper pipe?
  16. KIAB

    KIAB Well-Known Member

  17. terrymac

    terrymac Active Member

    If I were you I would remove one of the cold rads ,and connect a hose to the lockshield then open the valve and see what flow is like and see if any air / spluttering. Repeat on the trv valve ( or wheel head if that's what you have ). Depending on results you may need to do same to the other cold rads. If you have a severe blockage on the return line communal to all cold rads ,you could run a very strong magnet along the pipe. Any magnetite build up within the pipe will attract the magnet and you will sure find out where you need to cut into pipework.
  18. KIAB

    KIAB Well-Known Member

    This in brass or plastic will screw directly to the lockshield.

  19. dobbie

    dobbie Well-Known Member

    Depends if the lockshield is 3/4" or 1/2" if 3/4" no problem.
  20. KIAB

    KIAB Well-Known Member

    I presuming 1/2", still a quite 3/4" lockshields around, should have been clearer.:oops:

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