Sunday, May 13, 2012

Airlock Hell solved

12 May 2012: The Kingspan controller was working correctly during a sunny Saturday morning, but the temperature on the tubes was getting higher and higher. The pumps appeared to be working, but nothing was moving round. the temperature in the tubes was getting worryingly high, and i wanted the circuit to work so that it could cool.
     I am so grateful to my Volume meters which have a little spinning wheel indicating the speed of rotation. I had 'Airlocks Hell' - there was clearly an airlock in Both systems, the Solar tubes circuit and in the circuit linking the Heat Exchanger to the ground loop.
Airlock remover has now been installed
   In my attempts to get Jason to help (by phone), it was as if he was saying I should never have started - he hasn't heard of a solar tube system that isn't a closed circuit pumped up to pressure - and I don't have one of those special pumps - the whole principle of it being connected to a complex research circuit like this is such that it will never be a totally closed system - it will need to be topped up some times, and will be at gravity pressure initially, and then re-pressurised once it is working. (unfortunately, I don't have a pro quality pressure pump.) So I have to have a high altitude top-up tank.
    I still have to pay the plumbers, but until it has worked, I have been very unhappy to pay what with being left so high and dry, with work unfinished or requiring refixing, no offer of after-sales support. Yes, it's been my risk to take on the installation of the Heat Exchanger, but I was quoted £500 for having that done - and it would not be done in the thoughtful way I want, with ball valves to be able to modify the system - so I have sunk so much into it that I must continue.
   It refused to work all morning, but I patiently went to every part of the circuit where an airlock might form, releasing air. The heat exchanger is connected with flexible tubes and watered joints, so it is easy to undo them slightly and let air out. Still didn't work.
   I then remembered two things, that the old pump, when last used was non-functioning at the slow speed. Turned it to mid speed. The other was that the direct route for the air to move to the airlock remover was through a check valve - so air had to be let out by directly unscrewing an elbow joint to free it. .... and it finally worked! - so at midday, I could go to the farmers market and coffee bar with the comforting thought that it was working.
   Later in the day, I went to Screwfix and got a Tee-joint and an airlock remover, and fitted that, for a more permanent solution to the problem. It is all working now, without leaking, so I can gradually put the insulation back on the pipes.


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