Friday, April 16, 2010

Time for more plumbing?

16 April : At the moment, the flow from the GSHP divides more or less equally into:

  • roughly half up to the Sunboxes, 
  • and roughly half down directly into the ground loop. 

I discussed this a few days earlier - with the GSHP now working correctly (so has become a 'constant'), this particular question of flow division becomes more significant because it is a 'variable' that affects the results - and worse, it is an unknown variable. The actual fraction depends on the pump speed of the Wilo in the loft, since the pump speed in the GSHP is a constant setting. So, collected data is confused by this big unknown.

What I could or should do is fit another Danfoss solenoid valve that would CLOSE the direct link to the ground loop when the boxes are working, and send ALL the glycol through the sunboxes and then to the ground loop. As soon as enough heat has been downloaded, the thermostat would tell the Danfoss solenoid valve to open again, close the Danfoss in the loft, sending ALL from the GSHP to the Groundloop.

There is a risk in this if one or both of the Danfosses doesnt work and the GSHP is trying to push against Two closed valves. If the thermostat is turned off due to a fuse blowing or a wiring disconnection, the Danfosses have a feature in them to revert to a closed position. So there might need to be a 15mm open bypass pipe in case of that occuring. In case of a persistent problem, eg Thermostat failure, the Danfosses can be manually locked in the open position.
   Also, I have realised that you can get a Three-Way Danfoss, so that if one closes, the other route opens. This avoids the risk of a blockage, and could be set to connect either to the other part of the loop or to a bypass, with the default (no power) option to be sending through the ground loop only.
    Time for some Drawing first, then consult with Ice Energy, then a bit more Plumbing perhaps. At the same time, an Energy Flowmeter could be included. These are both 22mm units, so we definitely need the OK from Ice Energy.

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