Towel Radiators

Discussion in 'Plumbers' Talk' started by Kev63, Nov 9, 2019.

  1. Kev63

    Kev63 New Member

    Got two towel radiators which were recently installed upstairs to replace old rads in the bathrooms. Both overtime need bleeding after a few weeks after getting cold at top.

    Towel rad which was replaced at same time downstairs has no issues though.

    Cant see any obvious leaks anywhere and they replaced old rads when we moved into property - so not sure if the old ones had same problem.

    From what I can tell, the other rads upstairs (not been replaced) dont seem to have the same issue and its just these towels rads.

    Any ideas what it could be / fix?

    Traditional system with cold tank in loft and hot water tank in cupboard
  2. Mrs Plumber

    Mrs Plumber Member

    Air rises to highest point so usually it's the towel rads upstairs that get it.
    Could be corrosion in the system, sounds old. Could be a tiny leak somewhere sucking air in.
  3. Kev63

    Kev63 New Member

    System is probably 20 years old - same age as house.

    Any idea on how to fix?
  4. Heat

    Heat Screwfix Select

    Towel rails tend to gather air, especially the upper floor towel rails. It is something to do with their design and probably to do with the horizontal parts.
    On an open system air is naturally absorbed by the water and that air will turn into micro bubbles at boiler but only release from the water at a low pressure (generally high) point in system. Also can tend to be last rads on circuit.
    If open vented system and any slight leaks on suction side of pump or auto vents incorrectly positioned can draw in air when pump running.
    Also check on open systems that no pump over into wee heating f&e tank.

    To avoid much trouble with air, as said above, system firstly must be ideally fairly clean and not corroding.
    Also by far the best system is a sealed system if you have oil or gas.
    (A Combi boiler or a System boiler will already be a sealed system.)
    Sealed systems can’t absorb air, so can’t release much air once initial air is bled after a few weeks.
    Your system needs to be sound though, with no leaks or weeping rad valve glands etc, or system pressure drops too often.
    Another option is a deaerator, but not really if system changed to a sealed system.
  5. Kev63

    Kev63 New Member

    No idea what my system is called. It’s a hot water tank and cold tank in loft. Boiler downstairs and from what I can tell there is no pressure gauge on it
  6. Heat

    Heat Screwfix Select

    If it is open vented it normally will have a smaller tank for the heating for a feed and expansion tank.
  7. Kev63

    Kev63 New Member

    Still lost
  8. NoOhmToGoTo

    NoOhmToGoTo Active Member

    Is it just me or is anyone else thinking that our Kev may be a jolly prankster?
  9. Kev63

    Kev63 New Member

    Not at all mate, just dont know the first thing when it comes to plumbing so was after help here
  10. Joe the Plumber

    Joe the Plumber Screwfix Select

    There will be a small (typically four gallon) tank in your loft which feeds the central heating and hot water heating system. It also allows for expansion of the hot water in the radiators (etc), hence it's known as a feed and expansion (F&E) tank. This will be separate from the main loft cold water storage tank which feeds your hot water cylinder in the airing cupboard with the cold water that's heated up in the cylinder and comes out of your hot taps.

    I often find towel rail radiators seem to be the ones that get air in them for the simple reason the top of them is higher than the normal radiators, and air rises (as Mrs Plumber said, above). You may need to keep bleeding them for a few weeks until all the air is removed (and replaced by the water in your F&E tank).

    If you keep getting air in them, there could well be sludge in your central heating system (this is the corrosion Mrs P mentioned), one of the by-products of which is 'air' (ie gas). This will really need to be flushed out to stop the gas being produced and then inhibitor added to try to stop it coming back.

    You'll find that if the central heating system wasn't flushed and inhibitor added when the new towel rails were fitted, it probably invalidated their guarantee.

    I've stopped fitting radiators because there are so many things that can go wrong and, as an old f*rt, I've simply had enough!
    Kev63 likes this.
  11. Kev63

    Kev63 New Member

    cheers mate - very helpful! No idea if the system was flushed when they got installed.

    Not been in the house long and its my first home so will climb in loft tomorrow and see what this F@E tank looks like. I just presumed there was only one tank!

    ill keep bleeding for now then and see if problem goes away on its own accord, if not might have to get the pros in.

    thanks again
    Joe the Plumber likes this.
  12. koolpc

    koolpc Screwfix Select

    Correct. You should have 2 water tanks in the attic. One large one small.
  13. Joe the Plumber

    Joe the Plumber Screwfix Select

    If the system was drained down to fit the new towel rails, you may find there's still quite a lot of air in it. It can be very hard to get it all
    out when re-filling it, even though the rads all get hot.
  14. Mike58

    Mike58 Screwfix Select

    I have much the same system as you, and one radiator would always get air at the top. No leaks I could find and even after bleeeding there would be no top up of the header tank. Replaced it a couple of years back with a tall towel radiator and all close joints were remade - still the same in that air accumulates at the top. I just accept it as part of the operation and bleed every couple of weeks.
  15. Heat

    Heat Screwfix Select

    What I don’t understand about air gathering in towel radiators is it also happens even if the radiator is piped from low points of the pipe circuit.
    It seems to be something to do with the design of the towel rads.
    Also can be to do with the lowest pressure part of a system, which means the air releases.

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