Thursday, April 22, 2010

Three port Solenoid Valve ordered!

22 April : The Three-way valve has been ordered! A Danfoss 28mm three-port. In an earlier article, I pointed out that the split between the glycol going to the sunboxes and down to the ground was unknown, and therefore confusing the evaluation of this system. I found today from David Atkins that you can get 28mm versions, you just have to go to a specialist supplier - and extra cost of 28mm over 22mm is negligible - so order and be happy!
  He points out that earlier I was complaining about how I could have done this whole system with 22mm or even 15mm piping, since the sunboxes were tee'd on with their own pump. If the sole purpose was for summer time pumping to the ground, this would be sufficient as one is simply capturing free energy when it's available.

  Things have changed! I have since observed that the Realtime heat augmentation is a real benefit (visible during the day).
     I want to reorganise the plumbing and electrics so that the Entire Glycol circuit goes to the Sunbox when the thermostat commands, to maximise the Realtime and Diurnial benefit. The Interseasonal will be unaffected by this change, so it will be an improvement. If I had built the system with small tubing, this would be a non starter. But my huge investment in the larger diameter pipes will now pay off as I can push the entire ground loop through it without disadvantage. This means that the GSHP and the ground will rapidly exhaust ALL the heat that the sunboxes have to offer, then turn the sunboxes off, then continue with the ground until the sunboxes warm up again - and the cycle starts again. When this is happening, the little 40w pump in the loft will be reinforced with a powerful 200w pump inside the GSHP, thus downloading the sunbox heat faster!
  When the Danfoss arrives, one has to check it carefully (by blowing through it) to make sure that when the Sunbox electrics are turned off and the valve relaxes into a set position, the GSHP resumes business as usual, through the ground loop.
  As air temperature is now very important, I shall make sure that the Sunbox Mark2 is a lot more airtight when closed up. I had imagined that the boxes could run at night with the ventilation louvres open, but really, they get so much heat during the day, a bit more low quality heat at night is not worth the pump consumption.

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