Combi taking hot water from immersion tank

Discussion in 'Plumbers' Talk' started by Lee bradford, Nov 12, 2017.

  1. Lee bradford

    Lee bradford New Member

    Help just noticed combi boiler taking hot water from the immersion tank upstairs how is this possible grateful for any help
     
  2. Dr Bodgit

    Dr Bodgit Well-Known Member

    Could you clarify exactly what's happening and what water is going where....combi boilers don't use a hot water tank so I'm very confused. Photo of the tank would be helpful too.

    When was this installed?
     
  3. The Teach

    The Teach Active Member

    Seen combination boilers drawing water from unvented cylinders before o_O
     
  4. Lee bradford

    Lee bradford New Member

    20171114_003959.jpg 20171114_004013.jpg 20171114_003948.jpg 20171114_003850.jpg 20171114_003834.jpg
    Thank you very much for help bought the house 3 years ago the house is very old 1840s the elderly people had a government combi boiler installed free just before we moved in we have two black tanks in the Attic that I assume feed the toilets I'm quite sure the combi only does the radiators and the hot water comes from the tank in the airing cupboard the control box in the airing cupboard has hot water and heating controls if I turn off the heating controls the combi boiler doesn't work so if we leave it on and control it downstairs on the thermostat all is good this is the bit that I don't get when I turn the heating on downstairs and go upstairs to the tank you can hear the combi boiler taking hot water from the tank how can this be truly appreciate your input
     
  5. dobbie

    dobbie Well-Known Member

    You have a heat only boiler and not a combi boiler.
     
  6. KIAB

    KIAB Well-Known Member

    Vaillant open vent boiler.

    Strange location/installation for the LP522,should have been offset to one side.:confused:
     
    Last edited: Nov 14, 2017
  7. dobbie

    dobbie Well-Known Member

    It is a heat only boiler not a system boiler.
     
  8. KIAB

    KIAB Well-Known Member

    :oops::rolleyes:

    Glad someone is more awake than me.:rolleyes:
     
  9. Dr Bodgit

    Dr Bodgit Well-Known Member

    Are there any further questions or should I mark this ticket as closed? :p
     
  10. Devil's Advocate

    Devil's Advocate Well-Known Member

    We still don't know what Lee's actual issue is.
     
  11. Dave does Gas

    Dave does Gas Well-Known Member

    Can anyone spot the glaring error on the return pipe?

    Free smiley emoji to the first to see it
     
  12. Lee bradford

    Lee bradford New Member

    I'm confused because it's a heat only boiler does that mean it normal to take hot water from the immersion tank in the airing cupboard that means it's been heated twice you'll have to excuse me I know very little about boilers
     
  13. longboat

    longboat Well-Known Member

    Cylinder or boiler?
    Howay, gis a clue.
     
  14. Devil's Advocate

    Devil's Advocate Well-Known Member

    Upside-down vent? (If it is a vent...) Hang on - that's the flow. I dunno - drain cock too high?

    Anyhoo, Lee, I don't understand what you mean.

    You have a 'conventional' boiler, one that heats up circulating water in a 'closed' (but not 'sealed') system (with a wee expansion tank up in the loft). The output from your boiler is driven by a pump which then supplies a 3-port valve (see your first picture).

    The 3-port valve has an inlet (from the pump) and two outlets - one supplies the radiators and the other heats up the hot cylinder.

    This valve is controlled by the LP 522 timer. The boiler can heat just the rads, just the cylinder or both at the same time - depending on how that LP is set.

    Now, what is it you are saying that's wrong?
     
    Dr Bodgit likes this.
  15. Lee bradford

    Lee bradford New Member

     
  16. Dr Bodgit

    Dr Bodgit Well-Known Member

    Not quite. When you put the heating on, the pump will come on to circulate water that the boiler heats through the pipes and to the radiators. Similarly if you put the boiler on to heat the hot water, the pump also comes on and circulates water through the pipes via the hot water tank.
     
    Devil's Advocate likes this.
  17. Lee bradford

    Lee bradford New Member

    Thanks for your time I understand now I'll be able to sleep easier tonight knowing that my water isn't been heated twice I hope you can understand how it appeared to me like that this Screwfix forum is a great service
     
  18. Dave does Gas

    Dave does Gas Well-Known Member

    Do you really need a clue, as to which photo?

    Ok one clue, think about the position of the common return.
     
  19. Devil's Advocate

    Devil's Advocate Well-Known Member

    As Bodge says above.

    Up in your loft you should find two cold water tanks, one big and one much smaller. The big one is your CWS - Cold Water Storage tank, and this is what feeds your hot cylinder near its bottom, to replenish the water drawn off when you turn on a hot tap (the hot water comes out of the very top of that cylinder). This big tank gets drained every time you run a hot tap (and sometime the cold too), so needs to be kept topped up via the cold mains supply and a ball valve. Ie, that water keeps getting changed/replenished.

    The smaller tank is your F&E (Feed and Expansion) tank. This keeps the 'sealed' CH system topped up whenever it's needed, and also allows excess water to escape in to it when it heats up (water expands when heated). This wee tank - and the water inside it - is separate and doesn't mix with any other water. This is the water (with added chemicals to keep it 'clean') that runs through your boiler, through your pump and 3-port valve, through your radiators and also through the heating coil in your hot cylinder. So, when your boiler and pump runs, this is the water you hear rushing through the pipes. If it has a wee bit of air in it, it can be quite noisy.

    All normal.
     
  20. longboat

    longboat Well-Known Member

    Gis another one. Please.
    Have looked again and I'm not sure I can see the common return. Is that the point?
    I must admit that I'm not up to speed regarding the technicalities of these types of systems, I know the basics but have never had any in-depth training, as such.
    I can see the return just above the boiler in 15mm that must be an afterthought/add-on, that can't be the CR. . Surely?

    Are you pointing out the likelihood of a reverse flow problem?
     

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