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Thermal Store - Questions

  • 06-07-2009 11:40pm
    #1
    Quack13
    Registered Users, Registered Users 2 Posts: 111 ✭✭


    Someone has mentioned to me that a 'Thermal Store' based system might be something for me to consider when planning the heating/plumbing in our new build.

    Details are: story and a half dormer, 2700 sq. ft.
    Currently thinking of: Solar Panels, HRV, UFH (not decided on how to fuel this yet, possibly stove with back boiler)

    wall u-values of 0.16
    Windows U value of 0.8


    Anyhow,
    I am having some trouble totally 'grasping' the whole concept of the 'Thermal Store', and the advantages/disadvantages of such a system.

    I have some questions below and was wondering if someone could help me answer these:

    The big tank -heat bank- always has hot water in it and when you demand hot water to a tap or shower, mains water passes by this and is heated by a heat exchanger - is this right?


    Q1. If it's summer and the heating is off, then I assume the heat bank is cold? What happens when someone wants to wash their hands, have a shower or a bath? Does the heating have to be turned on and all the water in the heat bank heated? Would this not be slow and inefficent?

    Q2. If you're in the shower -running hot water and someone in another bathroom needs cold water, how does the system separate the types of water hot to the shower and cold to the bathroom? Or if you're having a shower at X degrees and someone else is washing dishes at Y degrees, how does the system separate the temperatures? Maybe there's cold feeds going to all taps, showers etc. and it's up to you to adjust the temperature?


    Q3. If it's doing your room heating i.e. rads or whatever, does this affect the hot water to baths etc. I presume the system will be trying to send out all the water in the heat bank to heat the rads, so does that mean it would take forever to heat water for a bath? That's the way it is with conventional oil boiler.

    Q4. What size is it i.e. tank etc?

    Q5. What are the costs of such a system?


    Any help would be appreciated!

    Q


Comments

  • #2
    kevymoss
    Registered Users, Registered Users 2 Posts: 26 ✭kevymoss


    The big tank -heat bank- always has hot water in it and when you demand hot water to a tap or shower, mains water passes by this and is heated by a heat exchanger - is this right?
    This is correct (a mainsflow system is also what it is known by!)

    Q1. If it's summer and the heating is off, then I assume the heat bank is cold? What happens when someone wants to wash their hands, have a shower or a bath? Does the heating have to be turned on and all the water in the heat bank heated? Would this not be slow and inefficent?
    Similar to that of current standard installs where the boiler will have to be on for a certain amount of time but it does not heat the rads/ufh just the thermal store to provide hot water, the thermal store is highly eff and highly insulated (well the type I fit are!!)

    Q2. If you're in the shower -running hot water and someone in another bathroom needs cold water, how does the system separate the types of water hot to the shower and cold to the bathroom? Or if you're having a shower at X degrees and someone else is washing dishes at Y degrees, how does the system separate the temperatures? Maybe there's cold feeds going to all taps, showers etc. and it's up to you to adjust the temperature?
    Depending on teh type of taps. Normally the showers are thermostatically controlled. Also there is a mixing valve at teh cylinder!

    Q3. If it's doing your room heating i.e. rads or whatever, does this affect the hot water to baths etc. I presume the system will be trying to send out all the water in the heat bank to heat the rads, so does that mean it would take forever to heat water for a bath? That's the way it is with conventional oil boiler.
    A certain system set up is used to prevent this. Ie hot water draw out connections within the cylinder

    Q4. What size is it i.e. tank etc?
    Whatever you need. Anything up to 1000Ltrs

    Q5. What are the costs of such a system?
    Again depends on your setup. If using solar etc etc

    Thanks Vry Much
    PM me if you need any more info
    THanks
    Kevin McGuckin


  • #3
    RVR
    Closed Accounts Posts: 54 ✭✭RVR


    Quack13 wrote: »
    Q1. If it's summer and the heating is off, then I assume the heat bank is cold? What happens when someone wants to wash their hands, have a shower or a bath? Does the heating have to be turned on and all the water in the heat bank heated? Would this not be slow and inefficent?

    These types of tank use the principle of stratification - hot water rises and cold water falls.

    This means that in summer just the top of the tank needs to be kept hot. When the cold water for the taps and showers passes up through the coil or inner tank it is heated instantaneously by the surrounding hot central heating water before leaving the tank.

    Depending on the tank specs you could expect hot water at no less than 5-10 degrees less than the temperature of the central heating water in the tank (but this depends on flowrate etc).

    Since the tank is usually kept at 50/60 degrees plus, this should give you hot water that is hotter than you need for most applications.

    Besides, a lot of modern systems have solar connected so the tank would be heated in the summer anyway!


  • #4
    redonly
    Registered Users, Registered Users 2 Posts: 25 ✭redonly


    I like the idea of a stratification tank but..........
    Is a thermal store/stratification tank/buffer tank all the same thing?

    where can you get a 600l/800l stratification tank, is there any particular brand/type the best?


  • #5
    Carlow52
    Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    redonly wrote: »
    I like the idea of a stratification tank but..........
    1: Is a thermal store/stratification tank/buffer tank all the same thing?

    2: where can you get a 600l/800l stratification tank, is there any particular brand/type the best?

    Buffer and thermal store mostly the same idea.

    The stratification tank that does what RVR describes
    This means that in summer just the top of the tank needs to be kept hot. When the cold water for the taps and showers passes up through the coil or inner tank it is heated instantaneously by the surrounding hot central heating water before leaving the tank.

    is a different animal and is more expensive because the 'instantaneous' aspect requires a good quality, high performance heat exchanger. Generally these tanks are much larger.

    One application being rolled out now is to use the thermal store as an input to a combi CH boiler which means u heat the water to above 60C only as required. These means u have no 'hot press' cylinder so it raises the question of a backup source of heating the water if the boiler stops working unless u stick a few immersion elements in the thermal store and then have the capacity to by pass the combi boiler.

    Come back if we can help develop your though lines further

    On pricing/brand do a web search


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