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  • Winter is on it's way ...

    This is not a dystopian prediction - but temperature in Denmark is close to 0 Celcius, and I have not yet put antifreeze into my solar panels. What function in my UVR610s-mod can I use so my solar pump automatically start when temperature is say below 1 C? The function "Solar Control" does not mention anything regarding "low temperature" (frost protection). Thank you.

  • #2
    The SOLAR function assumes you are either using anti-freeze in the heat medium as required, or the installed system is of the Drain-Back type.

    Glycol and other anti-freeze additives have some disadvantages over using 100% water, for instance less heat capacity, (minor) pollution in case of a leak. It also makes it more difficult, than using just water. Water is readily available, and you don't have to check the freezing point. No need for a stock of glycol or other anti-freeze additive.

    In all my FUTURE systems, I will only be using the Drain-Back method, as it has so many advantages. It must be designed and built very carefully, though, to ensure a proper drainback. Many systems have been damaged previously, when they didn't drain back properly. Not only the pipes but the solar panels themselves would burst or otherwise start to leak.

    I my current systems, I add anti-freeze for most temperature scenarios, but it only takes one single colder than normal day, to break the system permanently. Hence, I always build in anti-frost measures. With that, I also build in protection against overheating. I can do this, using underfloor heating and such. Although you rarely need extra heating in an overheat situation, I will sacrifice the comfort, to save the system. Along with an alarm to email, and via the message beeping function, I alert the user that action needs to be taken (like covering the panels, at least partly, if possible).

    The way to solve all these issues is simple, but one first has to consider how the T.A. programming work. Think of it as a large spreadsheet, where each cell in the spreadsheet is like a cell in the spreadsheet. This means that all cells (functions) run all the time, simultaneously. That is, until you tell them NOT to run. This is a powerful, but also essential part of each function: Enable function:

    Click image for larger version  Name:	EnableFunction.jpg Views:	0 Size:	4.8 KB ID:	167

    Before we run the Solar control funtion at all, we want to ensure the system isn't freezing up, or overheating. Using the enable function (to disable it), the system is now overriding the normal operation, to prevent damage. Here is an example of a simple setup with two essential temperature probes (solar collector and heat buffer temperature), as well as two outputs, a solar pump and a heating system pump. The latter might not be necessary, especially for freezing situations. In my systems, however, I am able to send the liquid from the solar collectors to a heat exchanger in contact with the underfloor heating, without using the heat buffer at all. My systems are more complicated, this posted example is just a simple setup, to demonstrate the principles used.

    On a hot summers day, without a drain-back system, it might be necessary to sink excess heat from the panels, into the heating system of the house. Otherwise you could risk a boiling event where the water-glycol mixture escapes out the overpressure safety valve. You could call that a Drainback function, but obviously, the liquid is now lost and you will have to refill the system again before it becomes operational.

    Click image for larger version  Name:	AntiFrostAntiBoilSolar.jpg Views:	0 Size:	74.1 KB ID:	168

    This is a setup using only three functions, which will protect against both freezing and overheat, using both the water buffer/tank as well as heating system, to absorb any temperature that is either too low or too high. Ideally, the system will be designed in a way which it will not be necessary with the overheat function. In this case, the overheat function will simply never be active.

    All other functions, for heating and whatever else the system does, should be connected to the two comparison functions above. If the system is freezing or boiling, other functions will have to wait (ie, be disabled)

    Before even programming the system, a flow chart should be made. This ensures the logic is the way you intend it to be. Here is an example:

    Click image for larger version  Name:	SB102 Frost and overheat protection.jpg Views:	0 Size:	251.1 KB ID:	169
    I hope this answers your question, otherwise feel free to ask further questions.
    Last edited by Core; 11-30-2021, 01:09 AM.

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    • #3
      Thank you for answering and as well explaining the principle. Very helpful.

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