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Which hot water cylinder?

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  • 05-07-2006 12:35pm
    #1
    vallo
    Closed Accounts Posts: 243 ✭✭


    I have a standard indirect insulated copper cylinder and am considering upgrading to an unvented system : Ariston stainless steel or Coppercraft Phoenix.

    At the moment if the heat goes on for 2 hours in the evening, next morning the water is luke warm at best. I want to improve on this so that I don't need to boost from the immersion or put in a pumped electric shower like Mira or Triton.

    I've been told that the stainless steel cylinder will lose very little heat - only 4 degrees in 24 hours!

    So my questions are:
    Does anyone have experience of these unvented systems and the stainless steel variety in particular?
    Do they really retain heat - e.g if the heating is on in the evening, will that provide piping hot water for showers next morning?
    Can anyone recommend a good installer for such a system - I'm price sensitive ;-)
    Thanks in advance


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    #2
    eddiej
    Registered Users Posts: 235 ✭✭eddiej


    Vallo,

    Dont mean to hijack the thread but do you know what is the cheapest option for heating the water during the summer i.e. is it best to use the heating or the immersion


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    #3
    vallo
    Closed Accounts Posts: 243 ✭✭vallo


    That all depends on what kind of gas heating package and ESB package you have.
    Your gas should be cheaper, otherwise why have your water heated by the gas boiler in the first place. And even if you use no gas during the summer months you still pay fixed charges.
    However, it could be that night-rate electricity could heat the water in your cylinder more cheaply than running your gas boiler - and then it comes back to my original question as to whether the hot water cylinder will keep it warm for long enough for you to use it!


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    #4
    gonk
    Closed Accounts Posts: 144 ✭✭gonk


    I use a standard copper cylinder with the factory-fitted spray on foam insulation. I heat water overnight at night-rate and it stays piping hot all day.


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    #5
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    http://www.acv-uk.com/tanks.htm

    the standard copper (foam insulated) tanks should be banned...
    they lose way too much heat. I had one and my boiler used to start about every two hours to keep the water at an acceptable temp.
    bought one of these ACV tanks... now the boiler only runs for about 10min every 12-16 hours. little bit more expensive but well worth it
    now we have hot water 24hours a day 7 days a week...


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    #6
    Wigster
    Registered Users Posts: 94 ✭✭Wigster


    \m/_(>_<)_\m/ , is this a pressurised cyclinder. Are they easy to install? Which model did you go for?


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    #7
    mukki
    Closed Accounts Posts: 2,669 ✭✭✭mukki


    \m/_(>_<)_\m/ wrote:
    http://www.acv-uk.com/tanks.htm

    the standard copper (foam insulated) tanks should be banned...
    they lose way too much heat. I had one and my boiler used to start about every two hours to keep the water at an acceptable temp.
    bought one of these ACV tanks... now the boiler only runs for about 10min every 12-16 hours. little bit more expensive but well worth it
    now we have hot water 24hours a day 7 days a week...


    great link, and good advice, will deffo put more thought into the tank in my build now


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    #8
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    Wigster wrote:
    \m/_(>_<)_\m/ , is this a pressurised cyclinder. Are they easy to install? Which model did you go for?


    i went for the Smart Line SLE 130, even though i don't have the electric immersion installed. (heating your water by electric is probably the most inefficient way to heat water but i wanted the option to install the electric heating element later).
    Installation is very easy and they are a very nice and tidy unit as well. Mine is pressurized and for €200 extra the sell you the pressure kit, again very easy to install. but you don't have to have it pressurized.

    also one should look at a mixing valve just aftre the hot water outlet. set this to whatever temp you want the water at the taps (30-40c) and this will mix cold water with your hot as it leave the tank... this will cut down the amount of hot water you use... i mean think about it.... you run your hot bath, then have to mix in cold water to cool it down...think of the waist...i know they all seem like little things but the savings are huge


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    #9
    tribesman
    Closed Accounts Posts: 113 ✭✭tribesman


    \m/_(>_<)_\m/ wrote:
    also one should look at a mixing valve just aftre the hot water outlet. set this to whatever temp you want the water at the taps (30-40c) and this will mix cold water with your hot as it leave the tank... this will cut down the amount of hot water you use... i mean think about it.... you run your hot bath, then have to mix in cold water to cool it down...think of the waist...i know they all seem like little things but the savings are huge

    What difference does it make whether you do the mixing at the bath or just coming out of the tank? I can't see how this is more efficient. More convenient maybe but not more efficient.


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    #10
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    tribesman wrote:
    What difference does it make whether you do the mixing at the bath or just coming out of the tank? I can't see how this is more efficient. More convenient maybe but not more efficient.

    physics my boy simple physics.

    rather that having a bath full of hot water and using cold to cool it down.
    fill the bath with cool water and no energy loss trying to cool it down.


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    #11
    tribesman
    Closed Accounts Posts: 113 ✭✭tribesman


    Yeah, but you're cooling it down by mixing it with cold water just after the hot comes out of the tank. Have you not just moved the energy loss from the bathroom to the hotpress?


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    #12
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    tribesman wrote:
    Yeah, but you're cooling it down by mixing it with cold water just after the hot comes out of the tank. Have you not just moved the energy loss from the bathroom to the hotpress?

    your not cooling your mixing...

    less volume of hot water used...

    anyway, listen you do it what ever want you want my boy.
    im here just trying to give a little good advice not trying to find holes in others people advice.
    by the way have you anything useful to offer here.


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    #13
    BuilderBob
    Registered Users Posts: 63 ✭✭BuilderBob


    \m/_(>_<)_\m/

    Are they expensive?
    Could you be a bit more detailsed on the savings?

    Could it DIY? Drawings and tech spec don't look too bad.
    If you've already answered these questions in another thread just point me in the right direction.


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    #14
    tribesman
    Closed Accounts Posts: 113 ✭✭tribesman


    Sorry, didn't mean to sound so negative. Its just that I am interested in good ideas to minimize waste of hot water but I'm not convinced that this one does that.

    I think that it is a good safety feature though because it prevents scalding if the water in the cylinder is very hot.
    Also useful if you don't have mixer taps.

    Seems to me though that mixing IS cooling though whether you do it at the bath or the cylinder.


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    #15
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    BuilderBob wrote:
    \m/_(>_<)_\m/

    Are they expensive?
    Could you be a bit more detailsed on the savings?

    Could it DIY? Drawings and tech spec don't look too bad.
    If you've already answered these questions in another thread just point me in the right direction.

    this particular one is about €1000 for the lot(this includes the pressure kit)
    savings... about €5 a month so far, but we are just after having a baby so our heating is all over the place from last year so cant really compare and we used never have hot water all day, just throw on the immersion or heating an hour before when we needed it so that was a huge energy loss.
    so €5 a month + hot water all day


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    #16
    pipers
    Closed Accounts Posts: 179 ✭✭pipers


    \m/_(>_<)_\m/ wrote:
    physics my boy simple physics.

    rather that having a bath full of hot water and using cold to cool it down.
    fill the bath with cool water and no energy loss trying to cool it down.


    Excellent method,it is common in all new healthcare installations, which helps reduce the risk of legionella.


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    #17
    \m/_(>_<)_\m/
    Closed Accounts Posts: 1,222 ✭✭✭\m/_(>_<)_\m/


    pipers wrote:
    Excellent method,it is common in all new healthcare installations, which helps reduce the risk of legionella.
    didn't know this, thank for the information...so that another plus for this method.


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    #18
    Alun
    Registered Users Posts: 21,467 ✭✭✭✭Alun


    \m/_(>_<)_\m/ wrote:
    physics my boy simple physics.

    rather that having a bath full of hot water and using cold to cool it down.
    fill the bath with cool water and no energy loss trying to cool it down.
    :confused::confused::confused:

    OK, I have a bath that contains, say 100 litres of water. If I fill it with 50 litres of hot and 50 litres of cold water either from separate taps or a mixer tap, or fill it with a pre-mixed mixture of hot and water from a mixer valve just after the tank in exactly the same proportions, I've used exactly the same amount of hot water in the process haven't I?

    I'd also like to know how exactly this prevents legionella contamination?


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    #19
    tribesman
    Closed Accounts Posts: 113 ✭✭tribesman


    Alun wrote:
    OK, I have a bath that contains, say 100 litres of water. If I fill it with 50 litres of hot and 50 litres of cold water either from separate taps or a mixer tap, or fill it with a pre-mixed mixture of hot and water from a mixer valve just after the tank in exactly the same proportions, I've used exactly the same amount of hot water in the process haven't I?

    That's exactly the way I see it.
    Alun wrote:
    I'd also like to know how exactly this prevents legionella contamination?

    AFAIK the important thing with legionella is to heat the water to greater than 60 degrees. I reckon this mixer doesn't prevent legionella but makes it safer to heat the water to higher temps and prevents legionella in that way.


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    #20
    pipers
    Closed Accounts Posts: 179 ✭✭pipers


    tribesman wrote:
    AFAIK the important thing with legionella is to heat the water to greater than 60 degrees. I reckon this mixer doesn't prevent legionella but makes it safer to heat the water to higher temps and prevents legionella in that way.

    Spot on


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    #21
    vallo
    Closed Accounts Posts: 243 ✭✭vallo


    Thanks for all the feedback folks.

    Perhaps my existing copper cylinder is a dud - it is spray-on foam insulated like yours gonk, but maybe has more pipes coming out of it and loses heat for that reason. I can see that the vented systems would lose some heat through the vent ... but is it really that much more than the unvented?

    I still don't know whether to go ahead with a pressurised system or if the steel cylinder will really give me the heat retention I was hoping for. The last thing I want to do is to spend big money and not get any big advantages.

    Pipers, as a plumber, what is your opinion of the different HWCs available?


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    #22
    gonk
    Closed Accounts Posts: 144 ✭✭gonk


    vallo wrote:
    Perhaps my existing copper cylinder is a dud - it is spray-on foam insulated like yours gonk, but maybe has more pipes coming out of it and loses heat for that reason.

    Dunno, but I've had these in two houses now, using night-rate electricity to heat water for daytime use, and they both worked very well.


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