Radiators plumbed in to flow only - help !!

Discussion in 'Plumbers' Talk' started by JonnyNitro, Mar 30, 2007.

  1. JonnyNitro

    JonnyNitro New Member

    Moved in to my new house a couple of months ago, it was built in 1960s and to date I've had no problems with my heating or boiler, everything fine. New boiler was put in about 10 years ago. Standard vented system, boiler in loft.

    I've just noticed something pretty odd about my upstairs radiators though. Instead of having separate flow and return pipes, each upstairs rad is just teeing off the same supply pipe on both sides of the rad.


    All the upstairs rads have been installed in this manner but the downstairs rads as far as I can see are installed in the usual separate flow/return way.

    Whilst the old saying; "if it ain't broke don't fix it" springs to mind, can anyone help me out by explaining why everything seems to be working just fine, and what if any potential problems I may come across by having this weird style of pipework for my central heating system.

    If it's all ok as is, then maybe the next time I want to add a new radiator to an existing system, I should do it in this manner to cut down on pipe work.......
  2. Zorro

    Zorro New Member

    Looks like you have got an old one-pipe setup (which runs around on one circuit).

    The problem with most one-pipe systems is that if you turn one of the first radiators off, it'll shut the rest of them down. This wont happen with yours as your pipework is set up differently.
  3. devil's advocate

    devil's advocate New Member

    Hi Jonny.

    What you have is a one-pipe system, at least on the upstairs! You might have the same downstairs with the connecting pipe hidden below floor level?

    Basically, it works, but isn't as effective as a conventional system - the rads at the 'end' of the loop tend to be cooler as the water has given up most of its heat by the time it gets to them.

    As you no doubt realise, the main flow travels around the unbroken loop but water will also flow through the rad as it's also a fairly easy path. The rads will probably be fitted with 'full-bore' valves to allow unrestricted flow through them - if you ever need to replace a valve, or fit TRVs, you need to use the type designed for one-pipe systems.

    When your boiler finally gives up the ghost, you'll almost certainly have to fit a condensing type. Apparently, it won't be as efficient on a one-pipe system, although it should work. Perhaps save up to have it re-done at that time?
  4. the tradesman

    the tradesman New Member

    souds like someone took a short cut, and picked up the flow one end and into the return the other, years ago most buildings had a "one pipe system" so nothing wrong there, but a two pipe system helped with balancing the rads, which you seem to have most of, as you said, if it aint broke, dont fix it!
  5. plummit

    plummit New Member

    Yes as others have said, Is a one piped system.
    The photo that you put on, helps a great deal, and shows that the "T" piece is swept.
  6. JonnyNitro

    JonnyNitro New Member

    Thanks for all the info, most helpful.

    So, I've got a 1 pipe system upstairs and a standard flow/return system downstairs. (I've checked the kitchen rad and it's absolutely definitely flow & return).

    Does this mean in all likelihood that the flow from the boiler in the loft passes thru all the upstairs rads in the 1 pipe system, then travels downstairs where it switches to flow/return system ?

    I'm getting a bit confused trying to get my head around it, but that sounds feasible doesn't it ?
  7. devil's advocate

    devil's advocate New Member

    Hi Jonny.

    Can you tell if the flow and return pipes coming from the upstairs to the downstairs rads are in the same place - ie: side by side-ish? Or, does the flow come 'down' in one room (probably the room where the 'first' upstairs rad is fitted) and the return go up in another?

    If the former, then your one-pipe seems to be effectively 'broken in to', and the two new ends have become your new flow and returns for your downstairs rads. It could, of course, be at the start of your upstairs ring - before it gets to your upstairs rads - instead of at the end of. Also, if this is the set-up, there will be a by-pass valve after the last downstairs rad (or, perhaps the pipes are just connected) so that the whole system doesn't shut off if you close every downstairs rad!

    If the later, then there is probably a 'tee' coming off the start of your upstairs 'ring', which provides the flow for the downstairs, and another tee at the other end which connects the return from downstairs.

    I suspect the former.

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