Monday, April 2, 2012

Tubes, Heat Exchanger, Scaffold

2 April 2012: The first of April provided the best possible conditions for testing the new tubes - cool air temperature but very sunny. I have insulated the pipe at the end of the array, and kept an eye on its operation. I am sure it will work better in the summer. When the heat pump works, the tube array does seem to suffer from 'thermal surprise' when liquid at 5ºC or less is delivered to it after the GHSP comes on.
   The System 23 (swimming pool mode) allows for it to switch on if the delta-T is 5 degs, and it continues working until the delta-T reduces to 2 degs. This is a good feature which the existing AKO (used on the Sunbox) doesn't support, although on the AKO, I can provide the equivalent by programming in a hysteresis figure and a time delay before switch off. It is working quite well today even in overcast conditions, and I wish the energy meter was installed the right way round so I could see what we are capturing.

Heat Exchanger
It seems that for satisfactory working over the whole year, the Heat Exchanger is going to be needed, and I will try to work with an industry standard one instead of making one from pipes, box and sand. Jason has recommended a Thermofin model. Looking at the flow rates, the smallest would be sufficient, although larger would have more inertia.

The scaffolding is due to be moved around from the east wall to the south wall as there is too much danger in trying to repair the sunbox from a ladder. I've been up there, but even to exert some force on the jubilee clips requires force, space and angle, which would be dangerous. The fronts need to come off for best access.
   One thing I have learnt - my home crafted Sunbox is far more efficient than a commercial panel! It has great thermal inertia, and my main mistake was to rely on the old expansion bottle. The old one was sufficient for temperature variations from -5 to a maximum of 12ºC, whereas with the Sunbox, the variation is from -5º to about 30º, hence the need for a bottle. I have purchased a 12 litre bottle. I have asked Richard Pearson to relocate the scaffolding.

1 comment:

  1. I have been looking for something like this on the heat equipment. Your post got me a step further in the right direction. Many thanks :-)

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