Friday, March 26, 2010

Heat pump brain fever

26 March: I have been thinking back to the trail of events that led to this whole project.
  Basically we have a heatpump with a some sort of problem with its temperature management . It frequently goes into red light condition, all the green lights on, and tries to push the water temperature up, up up, up, until it shuts down with a redlight. Sometimes I watch it, going 58, 59, 60, 61, 62... . This might not occur for some days, and then it gets a chronic condition of doing it several times a day.
   The whole business of obsessive meter reading and struggling to think of ways to charge the ground began with my frustration about water temperature management over a year ago. We don't feel we can leave it on when we go out for any length of time (which risks frost damage in wintertime.) And one of my worries was about depletion of the heat down below, and wondering how to replace it.
   I have a friend, Mike Seibert, who was an architect/housebuilder who suggested that new houses should have solar panels to warm up a slab of concrete under the house, and in the same slab, the GSHP would pull the same heat out. We didn't doubt it would work, but the question was, 'how big does the concrete need to be?' This could depend on the house location, the heat loss and size of the house, and the capacity of the heatpump, and density of pipe grid.... so many variables!

So, I started out on this project. Ice Energy offered me some pipe-meshes, and I finished up with the black swimming pool panels. The sunboxes were a way to make them work with warm air as well as with sun.

    Overall I have had a lot of fun and learning, without spending too much, and the Sunboxes really are working, so now I am hunting down the next way to improve performance. Now that we are likely to be presenting the Sunboxes at the Shanghai conference, we need to isolate every variable that can confuse data monitoring. We have enough variables to deal with already such as the weather, pump speed setting, sunbox ventilation setting, etc, but at the base of all this we need one thing to be reliably constant; the Heatpump itself. We need the heatpump to respond correctly to changes of ground temperature, and achieve a better COP if the temperature improves. If it is going Amok once or twice a day and trying to heat the water temperature to pasteurisation levels (well over 60ÂșC) this is confusing the readings.
    I have talked to Ice Energy and they are sending an engineer next week (1st April haha, but this choice of date is a coincidence), and for now I have turned the pasteurisation function off altogether - to zero, never happen. The problem could be either of Timing (doing it too often) or of Temperature (not knowing when to stop). There is a controller (called the REGO) inside that manages the whole GSHP. Unfortunately a lot of the data such as Hours of use and Hours of Additional heat would be set to zero with a new controller, but I will record all these on the 31st March so that the adjustment can be made in the spreadsheet.

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