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Placement of hot water cylinder and cold water tanks

Discussion in 'Plumbing and Central Heating' started by robbie77, 30 Dec 2009.

  1. robbie77

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    Hi

    Following on from a a previous post I have decided to move my gravity fed system to the loft that will allow a couple of meters height on the old setup
    The new setup will not have any where near the extra height from the cold water tank to the hot water tank.

    The question I have is does the pressure increase come from the height of the Hot water cylinder (I assume it does) and also how much higher does the cold water tank need to be above the hot water tank (it will not be much).

    Final question is I want to add a shower, will it just run from the same hot water tank if I install a separate cold water tank for it?

    Hope this makes sense!


    Thanks
     
  2. Steady

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    Height of cylinder doesn't matter.
    It's the height of the cold tank from the draw-off points that determines the degree of head.

    Presumably you are after a mixer shower-this would be fed by the hot and cold stored supplies.
     
  3. dextrous

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    Would advise installing a pump for the shower now rather than later - will be more cost effective to get the plumber to do this as part of the current modifications.
     
  4. robbie77

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    Thanks,

    Presumably the cold tank needs to be, at a minimum, just above the hot water tank so that it can feed it as opposed to side by side?
    I ask as tomorrow I am building a cradle for the tanks to sit on in the loft.

    re the shower pump, I will have a couple of meters height above the shower so will I still more than likely need one?

    For the mixer shower I will take a feed from the hot water tank and one from the normal cold water store or will it need its own cold water tanks i.e. avoid scalding?

    Thanks
     
  5. theheatinghelper

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    the higher the tank the greater the pressure, if you thinking of putting a pump on your shower supplies then some have a certain height the tank needs to be above the pump to kick the flow switches in. i have heard of pumped hot and cold supplies on bath and basin but never a toilet, i dont know how that would turn out, if the toilet would be ok with this? maybe someone else knows the answer to that. your shower supplies can be run from the same tank but by the looks of it, that tank its seems to be a 20 gallon tank(there or there abouts) Ive always recommended when putting a pump in that the tank be a 50 gallon in case the pump runs the tank dry.
     
  6. robbie77

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    Thanks for the info....

    Just to clarify that it will make no difference if the hot water tanks is just below the cold water tank. I do have the option of having the hot water tanks a couple of metres below the cold water supply (more difficult to achieve).

    If the pressure comes from the cold water supply then in theory could the hot water tank be at the same level of even below the shower or bath and still work OK given that the pressure is from the cold. I know that the hot water will rise but was thinking the pressure would be very poor?!

    Thanks again.....
     
  7. Hugh Jaleak

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    You're correct, the HW cylinder is fed from the cold storage cistern, but its the height of the cold storage that determines your HW pressure at the taps. Cylinder can be downstairs, provided the cold storage is just above level of the highest draw off it will work, albeit with poor pressure. The higher you can get the cold storage the better, but it is preferable to locate it above the cylinder, as the heat rising from the cylinder can help prevent the cold storage freezing at this time of year.

    You could try installing the shower on gravity supplies, leaving enough room to cut the pipes to retrofit a pump should you not be happy with the performance.
     
  8. theheatinghelper

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    just a question......i thought ...as in most cases i see , the cold and hot feeds come from the same tank......... and the smaller tanks (as seen in the picture) is what i think is the F&E tank for the heating but it seems to me your talking like the cold water storage supply for the cylinder is fed from one tank and the cold for the bath etc is supplied from another tank? it might be me having a blonde moment even though im bald but im a tad confused.
     
  9. robbie77

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    I think I have the traditional setup as in one cold water tank for the bath, shower, sinks and one for central heating expansion. Sorry for confusion there.

    I think I have two option if I am to stick with the gravity (seems like a good idea)

    One is to put both hot and cold tanks in the loft high up out the way, the main issue is there will be poor pressure due to the close proximity.



    The other option is to have the cold water tank high in the loft and have the HW tank in the bathroom airing cupboard with a slightly dog legged pipe run 35 degrees or something. This will give me some pressure but the pipe work will not be vertical?!



    Can someone advise please. Any help greatly appreciated.
     
  10. robbie77

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    I forgot to label the cold water storage in the loft! (the rectangle)
     
  11. dextrous

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    Hello Robbie

    It is solely the height of the cold water tank above the taps that determines the pressure. It matters very little how close the hot water cylinder is to the cold water tank, although additional restrictions of water flow thought pipes will have an effect.

    When you tunr on a hot water tap, it gets its water from the cold water tank, via the hot water cylinder.
     
  12. hardbasta

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    if you had both tank and cylinder in the loft or tank in loft & cylinder downstairs your pressure at the tap will be the same.your head pressure (hight of water level above outlet) will still be exactly the same.fill a 2m length oh hose pipe with water, if both open ends are the same level no water will come out, even though the dip in the hose (your cylinder) is on the floor. i hope this helps you understand a bit more :)
     
  13. robbie77

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    Cheers Dextrous


    So stick with plan A and put them both in the loft close to each other.
    This will give me a vertical pipe run and be much easier to do so good news.

    I am building the plat form to accommodate a 50 gallon tank so I can run a shower from it if need be.

    Sound like a plan..... I'll get building then
     
  14. dextrous

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    Both have advantages and disadvantages, but for a better flow rate the first is the better option as it involves less pipework from the cylinder to the bathroom taps (but more from the boiler). Plus it will be easier to install a pump should this prove necessary.
     
  15. griggs

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    Not entirely sure I understand the OPs intention.

    I would move the cold storage cistern into loft, but leave cylinder where it is
     

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