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Discuss Blocked cylinder circuit? in the Plumbing Forum area at UKPlumbersForums.co.uk.

  1. Sondstrom

    Sondstrom New Member

    BE49C5B9-705F-4D69-8461-307DE1D83F3D.jpeg I’ve not come across one of these before and I’m after a heads up on what lies beneath if anyone can help.
    This is the flow and return pipework and is connected into what would otherwise be a blanking cap or immersion element.
    There’s a few possibilities of course but I’m wondering if it’s just two pipes of different lengths, flow at the bottom, return at the top of a direct cylinder and plumbed into a y plan.
    The cylinder circulation is pretty much non existent but central heating is fine. I’ve tried googling all sorts but I’m getting nowhere finding a replacement.

  2. Sondstrom

    Sondstrom New Member

    It’s vented, as you’d no doubt guess.
  3. Rob Foster

    Rob Foster Top Contributor!!

    Just check as this is a really cute way of getting solar thermal heat into a cylinder..
    otherwise put a diagram up..so are the primary connections on the side there ? all hooked up to the boiler ? and h & c feeds top and bottom...it could be a crude primary cylinder heater cause the coil went years ago...
    tell customer its a bit off the wall and you cannot give a fixed price until you are paid to explore..then change the lot and charge loads
    its quite off the wall so you would not see it often, fun tho
    Last edited: Jul 8, 2019
  4. Sondstrom

    Sondstrom New Member

    Thanks centralheatking, there’s definitely no solar on this rented property. Those two pipes are the flow and return from the boiler, there’s no 22mm coil like you’d normally expect on a cylinder on a boiler system. I’m guessing it’s a cylinder designed for an immersion element only but has this handy gadget to allow conversion to a heat only boiler.
    • Like Like x 1
  5. snowhead

    snowhead Plumber

    It'll either be a loop of 15mm pipe a similar length to an immersion heater, in which case it won't have anywhere near the surface area of a more conventional 22mm coil.

    Or it will be a small bore heat exchanger internally connected to the 15 flow and return and will probably be scaled up.

    Or maybe a piece of 40mm tube sealed both ends with 1 x 15mm tube passing internally the the bottom with open end and the other 15mm tube into the top of the 40mm and open ended.

    Whichever it is, it's also only fed with 15mm flow and return so cylinder recovery would be slow even if the unit was working at full efficiency.

    Is it free of air in the 2 short stubbs?

    This appears to be 8mm or 10mm entry,
    Solar Panel Hot Water Immersion Coil Heat Exchanger Retrofit Coil | eBay
    • Like Like x 2
    • Informative Informative x 1
    Last edited: Jul 8, 2019
  6. Craig Watson

    Craig Watson Plumber GSR

    Could be something like this.
    Cylinder converters
    They are as you thought, a way of converting direct cylinders to indirect.
    • Like Like x 1
  7. Last Plumber

    Last Plumber Trusted Plumber GSR

    Or (following on from @snowhead@snowhead), they could be 'blades' which was another similar idea but they were four or five flat tubes like swords to look at but they did the same job. I see one side is equipped with a manual vent, is the other side vented into the system somehow? If not it could be air locked.
    The tube type had fins around them to increase the surface area over that of 15mm tube.
    They were never that impressive but they did work.
  8. Sondstrom

    Sondstrom New Member

    Thanks for all the help. I’ve dosed the system with Sentinel X800 and I’ll be back tomorrow to flush it all. I’ll see exactly what that thing is tomorrow and post it here.
    • Like Like x 1
  9. Sondstrom

    Sondstrom New Member

    It wasn’t air locked. I don’t like that old style of bleed valve so I just loosened the top it the compression T’s and it was dripping instantly... no notable hiss of air.
  10. Rob Foster

    Rob Foster Top Contributor!!

    well done so far tricky thing to walk into but as its your job & only you can sort it but thats the buzz of being a self employed fella on your own
    I still love it centralheatking
  11. Last Plumber

    Last Plumber Trusted Plumber GSR

    The Blade type were narrow and if the system is dirty, it didn't take much to slow them down to useless. I suppose all types were a bit naff really. It would take a long time to heat a cylinder of water, even when they were new.

    This is the 15mm type, some had fins as I mentioned earlier.
    • Like Like x 1
  12. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Pigs tail ch immersion heater for direct cylinders
  13. Best

    Best Trusted Plumber

    It looks to me to be a Hot Tube, which is just a coil that means you can convert an indirect cylinder into a twin coil, using that Hot Tube for oil or gas heating.
    Very prone to blockage and only heat part of the cylinder and slow recovery.
    • Like Like x 1
    • Agree Agree x 1
  14. Drewy

    Drewy New Member

    That’s what we used to call a hot rod. They’re not as good as a proper coil.
    • Agree Agree x 1
  15. Warmiger

    Warmiger New Member

    I would likely give best advise and just recommend upgrading it all.
    Like stated it will never be very efficient. Just explain to the customer there are a lot better methods than this and it will never be very good.
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