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  1. #1
    Join Date
    Mar 2008
    Posts
    22

    Default Solar panels + underfloor heating????

    Hi,

    Is there anyone out there who can tell me the best way couple the two systems together to maximise efficiency?? What I want is for the water that the boiler has to heat to already be preheated by the solar panels. Makes sense. Or if I order the two systems ie solar and underfloor will they automatically be connected to each other to maximise efficiency??? Sorry if this is a stupid question??

    Thanks,

    Tracy

  2. #2
    Join Date
    Oct 2007
    Posts
    424

    Default

    Solar panels work best in summer when you probably don't need UFH on

    So you can't really "link" them like this

    But the hot water cylinder ( which the solar panels will provide heat to ) also functions as a heat exchanger between the boiler and the UFH pipework , so your thinking is not totally devoid of logic .

    Essentially

    boiler - UFH
    Solar - hot water

    But in winter on sunnier days the solar will help the boiler . But this is a secondary consideration .

  3. #3

    Default

    Hi Tracy
    Some plumbers do the kind of thing you are suggesting, as far as I know the solar heat is dumped into a large buffer tank and it contributes to the heating load, especially in spring and autumn. This sort of a system also has the further advantage that if a properly sized buffer tank is used, it can increase the efficiency of your pellet boiler or what ever heat source you are using.

    Best if the one company designs the complete system, or alternatively a good plumber should be up to the job, or be able to recommend at least who could spec out the work if it is outside their area of expertise.

    You seem to be thinking in the right direction

    Good luck Glass

  4. #4
    Join Date
    Nov 2006
    Location
    Cork
    Posts
    40

    Default

    Tracy,

    Solar contributed space heating is relativley common addition to solar systems in germany and austria. To maximise the systems efficency a stratified storage vessel must be used and the lower the heating systems temperature the better (UFH is ideal).
    Solvis (no affiliation) supply stratified storage tanks and complete systems are sold by GoSolar in Ireland.
    The difference between a DHW solar system and solar contributed is a larger solar array (upto twice that of a DHW system) and a transfer station between the solar and your boiler are required (which would need lower supply and return temps to maximise efficency).
    These systems are most efficent in spring and autumn times but will contribute little or nothing in winter.

    Hope this helps

  5. #5
    Join Date
    Mar 2006
    Posts
    1,256

    Default re.

    The stored warm water can be directly fed into a modulating combi(-condensing) boiler where it'll receive the aditional energy to bring it to a save temperature level. For DHW this would be around 65 degrees Celsius.Or via a heatexchanger indirectly to the modulating boiler.
    Viessmann and other electric DHW supliers offer electric modules heating up pre-warmed water to a save level.
    I'm using UFH in combination with a thermal solar system with fine results, no boiler had to be turned on since end of February this year. Irelands first solar heated house if it covers the entire winter. We''ll see next year.

  6. #6
    Join Date
    Mar 2008
    Posts
    22

    Default ufh +solar energy

    HI,

    I am curious. What m2 are your solar panels? I have a quote for the system you are suggesting that involves 15m2. Is this overkill?? I am trying to heat a 3400sqft 2-storey house!

    Thanks,

    Tracy

  7. #7
    Join Date
    Mar 2006
    Posts
    1,256

    Default re.

    Sorry for answering late, tracy, I wasn't in the web for a while.
    I'm using 8 collectors ("SUNSHORE") holding 240 evacuated thermosyphon tubes,storing the energy in a 5,700 liter tank ("CARBERRY"). Collector surface is about 20-25 m2, the exact number I would have to check.
    When calculating energy demands use the international standard of "meter", for example squaremeter (m2)for the surfaces. It makes things easier.

  8. #8

    Default Grants for heating new builds are no more...

    Greener homes scheme II is now ended, and Greener Homes III scheme will not fund renewable heating technologies in new builds.

    http://www.dcmnr.gov.ie/Press+Releas...ceed+22000.htm

  9. #9
    Join Date
    Jan 2008
    Location
    Dublin
    Posts
    493

    Default

    Quote Originally Posted by Ducky510 View Post
    Solar contributed space heating is relativley common addition to solar systems in germany and austria. To maximise the systems efficency a stratified storage vessel must be used and the lower the heating systems temperature the better (UFH is ideal).
    Solvis (no affiliation) supply stratified storage tanks and complete systems are sold by GoSolar in Ireland.
    The difference between a DHW solar system and solar contributed is a larger solar array (upto twice that of a DHW system) and a transfer station between the solar and your boiler are required (which would need lower supply and return temps to maximise efficency).
    These systems are most efficent in spring and autumn times but will contribute little or nothing in winter.
    The Radiation levels in Ireland are about half the radiation level in Austria over the winter months.

  10. #10
    Join Date
    Mar 2006
    Posts
    1,256

    Default re.

    A large (solar) storage tank will hold a heatexchanger,for example a copper tube. This tube/heatexchanger will be connected to the existing heating system,in Tracy's case an UFH in combination with a boiler. The systems are seperated by two manually operated lever valves. There is no need for an extra control station provided the existing boiler has a thermometer showing the actual flow/return temperature.
    To run the solar heating system the boiler's flow temperature is reduced to the lowest possible temperature and the valve for the solar heat exchanger is opened by hand.
    The boiler's pump will kick-in as soon as the boiler is started, but the burner won't kick in because the temperature in the circuit is to high to trigger the burner's mechanism.
    So the boiler pump circulates the water from the solar storage tank through the UFH to the boiler and back to the solar storage tank. A very cheap, simple and relyable set-up. Tried and tested by myself .
    As soon as the temperature at the return sensor(at the boiler) drops below the desired level the lever valve has to be closed by hand and the boiler's flow temperature has to be set to the usual demanded level. This will cause the boiler to kick-in as usual.
    The lever valves -the separation of the boiler circuit and the solar circuit- is important. Otherwise the temperature generated by the boiler will not only pass through the UFH but will pass through the solar tank's heatexchanger as well and valuable fossile energy will be used to rise the temperature in the solar storage tank . A waste of energy !
    So the control station for the second circuit (the heatexchanger of the solar storage tank) can be saved. But for those who are incompetent to turn on a light when it is getting dark a sensor in the lamp will take over the job (smiley).
    In larger installments to be heated (appartment blocks,offices and hotels,breweries etc.) a secondary control station can't be avoided however. Unless the boiler is of a modern type and plumbed for the usage of secondary heat sources, there the control unit is already included in the boiler.
    Last edited by heinbloed; 11th July 2008 at 12:51 PM.

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