2 indirect cylinders inline

Discussion in 'Plumbers' Talk' started by Cliffo, Oct 3, 2017.

  1. Cliffo

    Cliffo New Member

    can I connect 2 cylinders together too increase volume of hot water.
    Is it possible too site a 2nd cylinder above the 1st, so that the cold water feeds into the bottom of the 1st cylinder and out the top into the bottom of the 2nd cylinder and then feeds from the top of that cylinder to the rest of the house.
    Also connecting the heating to the bottom cylinder only, so as to give more storage?


  2. Pollowick

    Pollowick Screwfix Select

    And as they are standing with no hot water being taken off, the upper one will go cold with no way to keep the water hot ... So, not very effective.

    A typical household indirect cylinder is 1200 high and 450 diameter. You can get them up to 1800 tall and 450 or 500 diameter. Going to an 1800 will give about an extra 60% hot water and increasing to 500 about 20% so doing both would give around 1.9 times as much. Easier to do than play around with two and it will work.

    And if you was a "custom" cylinder, which are not much more expensive, you can go to 600 diameter and even up to 2m or 2.4m tall!
    Last edited: Oct 3, 2017
  3. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    You can add more storage yes,

    What cylinders are they? Unvented or gravity
  4. Cliffo

    Cliffo New Member

    Thanks for the advice, I did think about a bigger cylinder but wasn't sure where to get it from.
    I will have to look into it some more
  5. Cliffo

    Cliffo New Member

    They are gravity fed indirect cylinders
  6. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    When you say you want to increase volume, is that flow rate or storage?
  7. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Cylinders you say? Do you have 2 already?

    What is the problem or symptom you are trying to resolve?
  8. Cliffo

    Cliffo New Member

    I am trying to increase storage, I have one in situ and can get another one from a friend.
    I looked at the cost of having one made earlier and it was the best part of £1000.00.
  9. Cliffo

    Cliffo New Member

    The problem is one bath and that's it, the next ones cold. The original cylinder is a 36 X 18
  10. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    You can add another cylinder but there’s lots to consider, it’s not really the best option

    If you sit it next to existing, you will need to either upsize the cold feed or drop another from the tank, if shared supply it has to be resistance paired

    They will need to have identical outlets before the join together,

    Will need separate cyl stats etc

    If you do this your also have to increase the tank size, the open vent needs to cut in etc,

    You could just add a direct one with an immersion but draw off would be cooled by the other if it’s uo to temp

    You best option and only advisory option really is to fit an unvented cyl

    Usage calcs will give you storage required, these cyls e.g (180ltr) can give you a reheat time of 20mins from stone cold, so they are heating it fast as you are drawing it off to

    The cost of gravity additions will be as costly as going unvented and usage benefits are non comparable
  11. Pollowick

    Pollowick Screwfix Select


    It is NOT his only option. The easiest and cheapest option is above - fit a larger cylinder.

    Where are you going for that? Recently I was quoted about £220 for a 1500x500 copper indirect plus £20 for a couple of additional flanges.
  12. Cliffo

    Cliffo New Member

    Ok that makes sense, the easiest option will be to replace the cylinder by the sound of it.
    Thanks for the advice, much appreciated.
  13. Cliffo

    Cliffo New Member

    I have just found the same size for £330, I will keep looking.
    It will be the easiest option by far, thanks for your help
  14. The Teach

    The Teach Screwfix Select

    Your cylinder could be slow to reheat the contents due to many reasons,age,coil scale build up,poor insulation.design,store temperature setting,lack of input kw's from heat source.etc.

    A new cylinder with fast reheat should be able to reheat the useable contents in 20 minutes (same amount of time your splashing around in the bath) but it all needs setting up correctly and a good heat source.

    Have used Albion ultracyl cylinders,the 1200x450 never had complaints even with a lot of family use.
  15. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    What I’m saying is by the time he buys a cyl, gets a plumber to fit it, he’s better off having mains pressure, more efficient modern alternative, no one has gravity anymore it’s rubbish

    His best option in the long run is to go unvented
  16. Pollowick

    Pollowick Screwfix Select

    Rubbish. £500 per year inspection fee - a total rip-off but it cannot be avoided. I was quoted ridiculous amounts to install an unvented system when an indirect vented cylinder is under £300.
    The Teach likes this.
  17. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    I can’t comment on your quotes mate

    I’ve fitted thousands and I’m only 37 so I’m probably more with it than the more matured members on here

    I charge £70 to inspect a cylinder,
  18. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    An indirect unvented 180 cyl is £360 with a 25 year garauntee

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