Top Half Radiators Hot, Bottom Half warm/cool?

Discussion in 'Plumbers' Talk' started by Chris101, Dec 1, 2013.

  1. liamo23

    liamo23 New Member

    Oh sorry also what are the risks and symptoms of unvented cylinder ?
     
  2. Ryluer

    Ryluer Well-Known Member

    Is your hot water taps mains pressure? You'll have a cold water storage cistern usually in the loft if its gravity.
     
  3. liamo23

    liamo23 New Member

    Yes the taps pressured by a pump which is under the stairs. It kicks in after about 5 seconds when turning taps on. There is an overflow tank in the attic/loft. Is that what you mean?
     
  4. Ryluer

    Ryluer Well-Known Member

    Sounds like its vented with a pump to boost the pressure.
     
  5. liamo23

    liamo23 New Member

    Ok and can you tell from the photos if the stats look ok? As in hi lo situation etc?
     
  6. Ryluer

    Ryluer Well-Known Member

    Looks like a pipe stat fitted which is probably a hi stat.
    Not likely to be a lo stat fitted I reckon.

    I assume you have solar panels?
     
  7. liamo23

    liamo23 New Member

    Ok well maybe I need to find out if I have a lo stat fitted. Yes I have solar panels. It's a house built in last 3 years!
     
  8. kiaora

    kiaora Screwfix Select

    hi
    there may be something somewhere. that says its ok, but for me its a definite no.

    the unvented cylinder has a potential to explode if not installed properly! especially with solid fuel, that will not just switch off.
    any one who was been on the course and is qualified to install and service one,
    will point out there are systems in place to avoid the water boiling, one is to have a zone valve to stop the water from physically getting to the cylinder coil.

    with the gravity system, the big problem is if the fire gets really hot, you have popped out, power cut, and faulty safety release and temp release, i'm afraid its good-by to your nice roof!

    there are videos on line that show you how they go bang.

    a tech bit if you are interested... as the temp rises, the pressure in the cylinder increases the boiling point of water,
    so if a leak occurs, the pressure reduces, and the sudden change of pressure causes the boiling point of the water to fall to atmospheric and it instantly boils, turns to steam, volume multiply s by 1700 times in a split second, and bang!

    hope that's clear
    regards
    peter
     
  9. kiaora

    kiaora Screwfix Select

    if its vented, sok
     
  10. liamo23

    liamo23 New Member

    :( :( well it's clear enough to know it is indeed scary. Do you remember I mentioned earlier in thread about the water temperature going up to nearly 70c and the humming noise well could that linked? ( it does not do that a lot just to note) . Is the tank in the loft enough to tell me it's vented??
     
  11. kiaora

    kiaora Screwfix Select

    Hi
    I may not be forfilling my duty of care, I have no problem helping anyone,
    But if it's open vented it's reasonably safe, unvented, it's not.

    That said, if the pipe coming out of the top of the cylinder, called the hot distribution pipe, that supply hot water to the system, has a tee installed that takes a pipe to the roof tank and is open to the atmosphere, without any valves .... it's vented,
    (That's called the vent pipe)

    Regards
    Peter
     
  12. I had this problem: 40kw boiler, 16 rads, some rads cold at the bottom. Flushed the system but problem remained. Bought and fitted new Grundfos pump. Turned it to max and the problem was solved.
     
  13. liamo23

    liamo23 New Member

    Hi
    Sorry for delay with reply. I've noticed once the rads that are open and have not been as hot as others if I toggle in anyway with the TRV valve on that rad I will hear the water gushing into and heating quickly. It's almost like you are waking the rad up. Even if it's 3 quarters open and you toggle it to half it kicks in. The boiler temperature is still going to mid 60's sometimes despite being set to 55c.

    Regards
    Liam
     
  14. Ryluer

    Ryluer Well-Known Member

    When the pump is running the only temperature you need be concerned with is the flow temp from the boiler. Which should sit between 60 and 70c. A clip on pipe dial thermometer is useful to monitor that temp.
    If the rads are sized correct, a return stat fitted and controlling the pump then this temp should remain fairly uniform once the system is up to operating temperature.
     

Share This Page