Monday, February 7, 2011

Ground Temperature Upcurve

6 Feb '11: Ground Temperature: I run the GSHP ground pump for the usual 20 mins, hopefully mixing the glycol up a bit as it goes round, and ensuring that it's a reasonable representation of the deep ground temperature. At today's date all three of my indicators (the Sunbox thermostat, the In and the Out temperatures of the GSHP) average at 11.4º. Last year it was 6.8º, but we were having a cold Spring.
   One of the major motivations for this is to prevent the deep ground from chilling. We are defrosting it in winter and charging it with additional heat in summer.
  During the winter of 2009-2010 I suspect that my measuring may not have been as rigorous as it is now, because of the more frequent oscillations, but the trend is quite visible. The sharp deeper troughs are probably when I didn't give enough time for the ground to recover after turning the GSHP off.
   Since the sunboxes were installed in mid March '10, the ground temperature recovered quickly to a higher point at the end of July '10, and has been pretty stable ever since. With the weather improving in Jan and Feb'11, the temperature has actually recovered slightly. I would dearly like to see the summer peak rise higher than in July '10.
  When there is demand from the GSHP for heat from the Sunboxes, there is an average delivery of about 1.80 kW from them, so there is still regular heat coming in, even if the Sun is not shining daily.

1 comment:

  1. Hi,

    Wondered if you could drop me an email with your contact details to

    I'd been following your progress via navitron, and wondered if we could maybe discuss some probono collaboration with our consultancy arm to help validate your results, add in some more metering etc if it would help.

    Annualised geo-storage of solar heat has been something I've been looking into for several years, so I'm very interested in your project, and from what I can see your data appears to be validating the concept.


    Gavin Andrews
    Leeds Solar / Leeds Energy Consultancy


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