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50 year old central heating pipework without inhibitor. Replace?

Discussion in 'Plumbing and Central Heating' started by 1001things, 9 Sep 2018.

  1. 1001things

    1001things

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    The central heating is original from when the property was built and, as the setup is Primatic, has never had or been able to have inhibitor. Only on 2nd boiler since new and I'd be very surprised if the system has been flushed at any time except for the boiler replacement, if that. Now intending to replace the current boiler and get rid of the Primatic so the system can have inhibitor. But should all the pipework be replaced at the same time? If not, what sort of lifetime should I expect post system update (ie new boiler, Primatic changed to something decent, inhibitor added and kept up to date)?

    I did the corrosion test of 2 jars containing an iron nail and copper coin, one with circuit water and one with fresh from the tap water and am attaching photos. The nails were as new as I had to hand, bright with no corrosion visible. Both nails corroded but the circuit water nail corroded MUCH faster than the tap water nail and also turned the water rust coloured. I also tried checking pH with some litmus paper I had to hand but that didn't help. Finally, according to the water provider the water here is 130 mg/l / 9.24 Clarke degree (moderate hard).

    Here is both jars, after 1 day. Circuit water on left, tap water on right. CentralHeatingCorrosionTestDay01Both.jpg
    Here are close ups of circuit (first) and tap (second)
    CentralHeatingCorrosionTestDay01CH.jpg CentralHeatingCorrosionTestDay01Tap.jpg

    Then after days here are both jars again
    CentralHeatingCorrosionTestDay10Both.jpg
    And here are close ups of circuit (first) and tap (second)
    CentralHeatingCorrosionTestDay10CH.jpg CentralHeatingCorrosionTestDay10Tap.jpg
     
  2. ReganAndCarter

    ReganAndCarter

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    Pipes should be OK if everything heats up well. I wouldn't rip the house apart to repipe unless there were known blockages. Majority of corrosion on a Primatic system will be in rads and there will probably be significant magnetite corrosion debris in them too. So, bare minimum would be PROPER THOROUGH power flush, making sure the person doing it uses a rad hammer. The rad hammer is to loosen the debris in rads which can attach itself to inside and be difficult to remove. If the rads are old, consider new ones - they're quite cheap these days. Finally, fit a quality magnetic filter on the return to boiler.

    I had exactly the same as you - original 50 year old Primatic system which was originally heated with a coal back boiler. Can be quite considerable amounts of crud in rads that have been run for 50 years without inhibitor.

    https://www.corgi-direct.com/kamco-...MI6I2l3b6u3QIVzZ3tCh0yEg_LEAQYASABEgKSjPD_BwE

    https://www.mrcentralheating.co.uk/adey-magnaclean-professional-2-filter-22mm
     
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  3. 1001things

    1001things

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    Thanks very much ReganAndCarter :). That's all good to know and much better than I expected.

    Just a follow up that I remembered after I'd submitted (and maybe ought to be a new thread? Not sure so I'll add here), re bleeding and so system condition. Until perhaps 2015 the system went years without a bleed at all and showed no need for it. Since then it has needed it increasingly, first and once only on a rad that is either the furthest or 2nd furthest from the boiler, then repeatedly on 2 other specific rads. The first of these is either the furthest or 2nd furthest from the boiler and is the only rad to have had its manual valve actually turned for at least a couple of decades. The second is one of 2 that are closest to the boiler and the only one to have had valves changed.

    The first mentioned (far away) of these regularly bled rads was turned off by the gas engineer I'd guess 4 years back as the room was barely used but when needed to turn it back on it developed a slight leak from the manual valve. Just needed a washer change if I remember correctly, which was easy as the valves are original Belmonts that can be worked on with the rad still in place.

    The second mentioned (near to) was, I believe, a problem rad briefly when the system was new and had its manual and lock-shield valves swapped end to end.

    Both of these rads need bleeding very regularly, with 'near to' containing the most gas each time. I bleed until the water runs clear, after a few seconds of dark water following the gas.
     
  4. oilboffin

    oilboffin

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    I'd be in cloned to put a cleaner in first drain after a week see what comes out then power flush I wouldn't use a rad hammer on an old system as some rads could be held together with rust just take things easy and you may not have a disaster.Bob
     
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  5. 1001things

    1001things

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    Thanks Bob :). Externally the rads are in excellent condition with no sign of corrosion or barely anything except smooth, complete paint (2 rads excepted, ones that have had towel racks on that have caused paint chipping) and when I've checked for cold mounds lower down (for sludge) only one rad seems to have a small area with the rest fine. Does this suggest what internal condition may be, swing your opinion either way?

    For what its worth, I'd definitely consider replacing all the rads anyway given that they are all a vintage pressed steel design and so may not (as I understand it) be as cost effective over the new boiler's lifespan as replacing with rads better suited to current boilers.
     
  6. Bodd

    Bodd

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    50 year old copper could well be better than the new stuff. we did go through a copper shortage I think in the 70s but not sure as there was a lot of sh!t about.
    Ask your engineer his view check that its not a one pipe system as well
     
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  7. ReganAndCarter

    ReganAndCarter

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    You're welcome, 1001. Frequent bleeding could be down to gas being produced as a by-product of the corrosion process. But without seeing the system, it could be other things too. I would be starting with a proper clean and dosing with corrosion inhibitor and get the system checked if this doesn't improve matters.

    Good point made by Bodd too re. one pipe. Personally that would make me more inclined to replace pipework, but others will probably not be worried by it.

    Good luck.
     
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  8. 1001things

    1001things

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    Thanks Bodd. I didn't even realise there'd been inferior quality copper piping. So had a brief search and most seem to talk about the problem being late 70s pipes, which would be reassuring as the pipes here are all early 70s.
     
  9. 1001things

    1001things

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    Re the one pipe Bodd and ReganAndCarter I had a look in a couple of books and online for identifiers. Will be trying the 'feel the pipes when starting up the CH' later but the valves are floor level both ends of the rads unlike the high level valve at one end of each rad as shown in the diagrams I've seen for one pipers. Plus no tilt (really, did/do people do this?) on the upper floor rads. So fingers crossed it is a two pipe.
     
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