Baxi Bermuda back boiler - kettling - worth flushing?

Discussion in 'Plumbing and Central Heating' started by EdTurtle, 23 Feb 2018.

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  1. EdTurtle

    EdTurtle

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    I have a baxi back boiler with gas front (front is a few years old and the back we think is 1974). I have a hot water tank with f&e in the loft. The heating is a C-plan setup.

    Basically, the boiler kettles a fair bit, despite me having turned it down under the fire (doesnt make any difference where the temp is set). The boiler also cycles a lot with the hot water calling for heat, cycles less with heating demand, but still cycles.

    We have taken one radiator off to change the pipes, and flushed it outside - a little bit of black water came out, no sludge though.

    When i put the radiator back on i have got some sentinel x100 to put back in (this was probably last done about 10 years ago - previous owners did it so i'm not sure). Will this be enough, or should i put some x400 or x800 in and flush it through to try and stop some of the kettling/cycling? Should i flush after i put the radiator back on, or before?

    Finally, is this a fairly accurate guide:

    https://timstephenson.me.uk/flushin...system-simple-something-you-really-should-do/

    Thanks
     
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  3. FiremanT

    FiremanT

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    No it is not. This is not the correct method to flush out a system.

    Finally…
    After a week of normal usage, repeat the process above for flushing the system – starting after the system’s been able to heat up to normal temperature.
    This time, you’re flushing out the cleaning chemicals along with whatever sludge (suspended in the water) it’s been able to dislodge and again let the water run until clear.
    Once you’re happy that you have clean water running out, close the F&E tank’s ball valve and pour in your bottle of inhibitor (eg: Fernox Central Heating Protector F1).

    With the inhibitor in the system, leave the F&E tank to refill and close your drain point’s valve.

    The method described will not clear all the disturbed gunk.

    And so many drain cocks will exhibit a tendency for being able to wind the nut right out, yet not allow any water to pass.
     
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  4. EdTurtle

    EdTurtle

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    So, what would the method be?

    Thanks
     
  5. 45yearsagasman

    45yearsagasman

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    I'd simply put some X200 in the system and see if it quietens the boiler. Isolate and drain a rad, then add the X200 via one of the top plugs. Refill the rad and let it circulate round the system. I wouldn't be to drastic with a boiler of that age.
     
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  6. EdTurtle

    EdTurtle

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    Can i leave x200 in the system indefinitely?

    Thanks
     
  7. Last edited by a moderator: 23 Feb 2018
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  8. EdTurtle

    EdTurtle

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    Thanks everyone :) Last question... can i put the x100 and x200 in the empty radiator together, and then fill the system back up, ie are they ok to mix neat?

    Thanks
     
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  10. FiremanT

    FiremanT

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    Essentially, fill, circulate, drain from EVERY drain point/drop. Repeat. Repeat. Keep repeating. Ideally use a Turbidity tube to make sure water is clean. and/or litmus paper. or, as most do, repeat until it is clear.
     
  11. EdTurtle

    EdTurtle

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    Ok, thanks. I'll try the x200 first, as that sounds easier!
     
  12. Hugh Jaleak

    Hugh Jaleak

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    Personally, if you are keen to sort this out, I'd chuck some X400 in, leave for a few weeks, drain, fill, circulate, drain, repeat as Fireman T suggests, to remove as much crud as possible from the system, then once you're happy you've got as much muck out as you're going to, refill adding X100 and X200, to remain in the system. X800 is for Powerflushing, not suitable for this application.

    I am also assuming from the boiler type, the system is open vented, in which case the chemical's can be added via the F&E cistern.
     
  13. andytw

    andytw

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    We have one of these in a let property which ran for years without problem then started a banging and popping. I wouldn't have called it kettling but you might. Long story short, problem was eventually found to be the plastic spreader insider the entrance to the heat exchanger. It is there to ensure all 4 sections of the heat exchanger get water running down them. In our case the spreader was damaged and 2 of the channels were not getting a flush of water so were boiling. The spreader is a cheap part but not not easy to access unfortunately.
    Our 552 has run as quiet as a mouse since the day the new spreader was fitted. This is now 7 or 8 years.
    You may find posts, or receive posts, that say the spreader is only required on gravity flow systems, this is not the case, I have the manual.

    For the record I also cleaned, flushed, replaced thermostat and then bought another heat exchanger. It was only when preparing to swap the HE the engineer found the broken spreader.
     
    Last edited: 24 Feb 2018
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  14. EdTurtle

    EdTurtle

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    Ok, both very helpful posts thanks :) I assume that since i am not gas registered that i cant change this part myself? I'll have a look online for the manual, or see if i can find it here (hopefully the old owners left it somewhere!)

    Thanks
     
  15. andytw

    andytw

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    Last edited: 24 Feb 2018
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