Gravity Hot Water System Advice

Discussion in 'Plumbers' Talk' started by Martin2017, Mar 5, 2017.

  1. Martin2017

    Martin2017 Member

    Hi guys, doing some renovation work in my downstairs bathroom and need some advice.

    Since being in this house there has always been a radiator half way up the downstairs bathroom wall. I've found out by taking back some false wall that this radiator is joined to the gravity hot water circuit, which I understand was common practice years ago for bathroom towel radiators.

    My question, is this radiator placed half way up the wall because it is on the gravity hot water circuit and need to be higher than the boiler in order to heat up?

    The boiler is a baxi back boiler, pre 1975.

    Thanks
     
  2. Glad its Friday

    Glad its Friday Active Member

    Correct.
    Do some renovation work on your heating system, that boiler will be well past it and quite possibly dangerous. Has it been serviced recently?
     
    KIAB likes this.
  3. Martin2017

    Martin2017 Member

    It's serviced every winter, plumber says it is working perfectly.

    So there's nothing I can do regarding the current position of the radiator coming off the hot water circuit, in terms of getting it down lower?
     
  4. KIAB

    KIAB Super Member

    Seriously look at getting it replaced, there a big difference between it working perfectly & being safe, metal gets rusty & thin with age,waterways scale up restricting flow,so a risk it could exploded.
     
  5. Martin2017

    Martin2017 Member

    I know. It's advice on my original question I'm looking for, thanks.
     
  6. Martin2017

    Martin2017 Member

    I've decided to t off from the central heating system. Not ideal for me as it's quite a run but there you go.
     
  7. Martin2017

    Martin2017 Member

    So last bit of advice needed. As I no longer need the radiator on the gravity fed hot water, do I cap off the two 15mm pipes that are t'd off from the boiler pipes or do I need to join the two together to form some sort of circuit that currently runs through the radiator that im removing? Ive attached a picture. Thanks
    sff.jpg
     
  8. Martin2017

    Martin2017 Member

    Sorry for replying to my own posts, but I can't seem to find an edit button.

    So, if someone could advise me on the above and also, whichever one of the above I have to do, am I correct in thinking I have to drain off the hot water tank to do it?
     
  9. kiaora

    kiaora Guest

    Hi
    No need to drain hot cylinder, just the primary water, at the boiler drain.

    Just cap off the two gravity trappings.

    Never know, you may decide you want the warm gravity towel rail in the summer?

    Regards
    Peter
     
  10. kiaora

    kiaora Guest

    The reason the radiator is higher up the wall, the return pipe must go downhill from the bottom of the rad to to boiler, just as the flow must go uphill from boiler to top of radiator.

    The return water is cooler/ heavier and falls back to the boiler, and the lighter/warmer water, is pushed out the boiler, and starts the thermo syphon,

    Regards
    Peter
     
  11. Martin2017

    Martin2017 Member

    Thanks Peter, I appreciate the help.

    You say primary water at the boiler drain, can you elaborate a bit on that please. "Boiler drain" isn't something Ive seen when reading up on "how to's".
     
  12. kiaora

    kiaora Guest

    Hi
    The primary water is the water in the radiators,

    The boiler will have a drain point on the pipes quite close to it.

    Normally the lowest point.

    Hope that's a bit clearer,

    Simply isolate the feed tank in the roof, connect hose to drain point, also called doc.
    When water is drained , check by loosening the nuts on the connector in the picture and remove connector and elbow, and fit compression cap ends

    At the same time, pipe up the new radiator to the heating curcuit

    Refill adding inhibitor,

    Regards
    Peter
     
  13. kiaora

    kiaora Guest

    Just noticed, that's a drain point in the picture, quite often, they don't work, but good luck
     
  14. kingbell69

    kingbell69 New Member

  15. Pollowick

    Pollowick Screwfix Select

    I hope that you only charge for time on site and not for travelling.
     
  16. Martin2017

    Martin2017 Member

    Thanks again Peter. I assumed the drain point in the picture was just for the hot water tank, due to it being directly under the tank location. I've just remembered that the drain point in the picture leaked around 8 years ago and my father who has now passed, replaced it, so it should drain from there.

    If you've got a spare minute just to enlighten me on, how doesn't the hot water tank empty when draining the system?
     
  17. kiaora

    kiaora Guest

    hi
    the water in the cylinder is the secondary water, normally supplied via the cold water storage tank in the loft.
    the primary water is supplied via the feed and expansion tank in the loft.

    i have assumed, you have an indirect cylinder?
    as in a coil in the cylinder? and the cylinder is fed via a large tank?, or a fortic?

    so.. the water in the cylinder, the water that flows to your bath, is not the same water going round the radiators.

    the is normally a coil of pipe in the cylinder that has the radiator water in it and the coil acts as a heat exchanger?

    hope that helps
    regards
    peter
     
  18. kiaora

    kiaora Guest

    ps
    the 4 pipe in the picture, are gravity hot water flow and return, and pumped heating flow and return

    the drain is normally on the return
     
  19. Martin2017

    Martin2017 Member

    Okay, I understand. Yes it's an immersion tank, which I assume is the coil inside you mention.

    When reading up ive found more than one name for the same thing which doesn't help me, lol.

    There's only one water cold water tank, which is directly above the hot water tank in the back bedroom. There's no second cold tank or a tank in the loft
     
  20. kiaora

    kiaora Guest

    a pic of you a/c hot cylinder may help?
    but, failing that, look at the cylinder, locate the 1" gravity pipes. flow and return.

    as the 1" pipe connects to the bottom of the cylinder, often there is a t and that is where the cold water is fed into the system?

    pic of the pipes ?
     

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