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24 hour hot water

  • 04-02-2013 11:38am
    #1
    Ah Here
    Closed Accounts Posts: 67 ✭✭


    Calling all plumbing experts!

    I have a 2500 sq ft house, built 2010, oil-fired underfloor heating. I am currently heating 2000 sq ft of the house to a constant temp of 18-19 degrees (not switching the heating on and off at certain times, which the installer said was the most efficent way to heat the house).

    There was a timer clock on the system, which was split into 2 zones (upstairs & downstairs) and hot water. The UFH manufacter recommeded that I remove this timer, as the system was not designed for it. this left me with no way to time the hot water, and therefore I have hot water 24 hours a day.

    My question is (and apologies if this is a stupid question) Is this the most cost-effective way to provide hot water, as the heating is on anyway, or sound I get a timer just for the hot water so I could have hot water for a few hours in the morning and a few in the evening?

    Thanks in advance for any reply- oil is expensive enough without wasting it.


Comments

  • #2
    corkgsxr
    Registered Users, Registered Users 2 Posts: 3,404 ✭✭✭corkgsxr


    its normally dearer to have a demand cylinder so id imagine it is wasteful.


  • #3
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    corkgsxr wrote: »
    its normally dearer to have a demand cylinder so id imagine it is wasteful.

    thanks for your reply, and sorry for my ignorance, but what is a demand cylinder?


  • #4
    corkgsxr
    Registered Users, Registered Users 2 Posts: 3,404 ✭✭✭corkgsxr


    Ah Here wrote: »
    thanks for your reply, and sorry for my ignorance, but what is a demand cylinder?

    cylinder drops tempature it calls for heat. so you have constant hot water.

    not what you have but you end up with similar result, constant hot water


  • #5
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    thanks again. As the same cylinder holds the water for the ufh and the hot water, does that mean there is no point in adding a timer? What about when the heating is off in the summer?


  • #6
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »
    thanks again. As the same cylinder holds the water for the ufh and the hot water, does that mean there is no point in adding a timer? What about when the heating is off in the summer?
    Do you have a thermal store rather than a dhw cylinder, i.e. basically a buffer tank with a dhw coil (pressurised) that heats your hw as it passes though the buffer?
    If so, very wasteful but you can make some changes to benefit in oil consumption.


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  • #7
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    Do you have a thermal store rather than a dhw cylinder, i.e. basically a buffer tank with a dhw coil (pressurised) that heats your hw as it passes though the buffer?
    If so, very wasteful but you can make some changes to benefit in oil consumption.

    Thanks. To be honest i dont know, but i dont think so


  • #8
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    How big is your DHW cylinder? Is it a "normal" looking one or a great big jalopy?


  • #9
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »
    As the same cylinder holds the water for the ufh and the hot water

    The reason I was asking was because if this statement.


  • #10
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    How big is your DHW cylinder? Is it a "normal" looking one or a great big jalopy?

    Its about 5ft tall


  • #11
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Why do you say the same cylinder holds the water for the UFH & the DHW?


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  • #12
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    Why do you say the same cylinder holds the water for the UFH & the DHW?

    Im just presuming as i only have one cylinder. As u can tell im no expert!


  • #13
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ok, presuming you do not have a thermal store but indeed have a standard DHW cylinder, then the best way is to zone this separately and heat for about 30 minutes in the morning & possibly 30 minutes in the evening, depending upon the amount of DHW that you use.
    The installation of a motorized valve & a two channel timeclock would be required. The cylinder should also have a cylinder thermostat, set to 60C, so that if the water was already hot & the boiler was timed to heat it, it would not fire the boiler as it was already at its desired temperature.
    There is no point in unnecessarily dumping heat into a cylinder that is already at a desired temperature, so zoning it is always best practice.


  • #14
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    Ok, presuming you do not have a thermal store but indeed have a standard DHW cylinder, then the best way is to zone this separately and heat for about 30 minutes in the morning & possibly 30 minutes in the evening, depending upon the amount of DHW that you use.
    The installation of a motorized valve & a two channel timeclock would be required. The cylinder should also have a cylinder thermostat, set to 60C, so that if the water was already hot & the boiler was timed to heat it, it would not fire the boiler as it was already at its desired temperature.
    There is no point in unnecessarily dumping heat into a cylinder that is already at a desired temperature, so zoning it is always best practice.

    Fair play, thanks for the detail reply. The cylinder already has a stat, i fogot to say i have a solar panel aswell. i presume as there was a clock already it would have a motorised valve?


  • #15
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    The cylinder stat should be wired to the motorized valve so follow the wire to see.


  • #16
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    The cylinder stat should be wired to the motorized valve so follow the wire to see.


    Indeed it is


  • #17
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »


    Indeed it is
    Job done so....
    All you need to do now is adjust the times it comes on. That was a cheap fix!


  • #18
    Dtp79
    Closed Accounts Posts: 2,097 ✭✭✭Dtp79


    Ah Here wrote: »

    Im just presuming as i only have one cylinder. As u can tell im no expert!
    Take a few pics


  • #19
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    Job done so....
    All you need to do now is adjust the times it comes on. That was a cheap fix!

    Thank but will that affect my ufh?


  • #20
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »

    Thank but will that affect my ufh?
    Improve it & use less fuel


  • #21
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    shane0007 wrote: »
    Improve it & use less fuel

    But the manufacturer said the heating was not designed for a clock?


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  • #22
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    I suppose my question is can I time the hot water while leaving the heating on constant? Is it possible and will it save money?


  • #23
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »

    But the manufacturer said the heating was not designed for a clock?
    Manufacturer is referring to the UFH heating side & not your dhw!


  • #24
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »
    I suppose my question is can I time the hot water while leaving the heating on constant? Is it possible and will it save money?
    Yes


  • #25
    Ah Here
    Closed Accounts Posts: 67 ✭✭Ah Here


    Spoke to an electrician about installing a time clock. He says that to heat the water morning/eve would use more oil than leaving it on constantly due to the size of the cylinder.


  • #26
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Ah Here wrote: »
    Spoke to an electrician about installing a time clock. He says that to heat the water morning/eve would use more oil than leaving it on constantly due to the size of the cylinder.
    Aye, I suppose he'd know alright....

    What size is the cylinder?


  • #27
    dathi
    Registered Users, Registered Users 2 Posts: 1,422 ✭✭✭dathi


    shane if there is a stat and a motorized valve on the cylinder then the valve closes when the cylinder reaches temp so there is not heat being pumped in 24/7 only when the temp falls in cylinder and valve opens.


  • #28
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    dathi wrote: »
    shane if there is a stat and a motorized valve on the cylinder then the valve closes when the cylinder reaches temp so there is not heat being pumped in 24/7 only when the temp falls in cylinder and valve opens.
    True but as long as the aux wire kills the power to the boiler to ensure interlock.


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