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Hot water circulation pump recommendations


superdiy
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I need a new circulation pump, currently I have the Laing D5/700, but the impeller is so unbalanced it lately gets stuck and I have to disassemble the pump to loosen it and to get it to work again and that is a ticking time-bomb in a PV hot water system. For those who don't know, the Laing pumps have spherical motors: The principle of the spherical motor, which was invented by Laing, is fundamentally different from conventional canned motor pumps. The only moving part in a spherical motor is a hemispherical rotor/impeller unit, which sits on an ultra-hard, wear-resistant ceramic ball. There are no conventional shaft bearings or seals.

I'm on my second Laing pump, first one worked well until one day when I worked on the solar system and accidentally closed the loop containing the hot water panel and the pump and while the water was heated by the sun the pressure went to high and eventually the pump's flange gave in.  So, not their fault, but mine.  I got another pump but from the beginning I could hear that the impeller was not very well balanced and it even caused the pipes to vibrate.  The vibration got worse with time and when the pumped water is hotter, usually later in the day, it is even worse.  It is now at a point where the impeller goes totally off balance, makes a few cluck cluck noises and then stops, it then starts spinning up again and when a certain spreed is reached it goes totally off balance again, make the cluck cluck noises and then stops, just to repeat the cycle. Sometimes the impeller gets stuck after such an episode and that is not good news when the panel sits in the sun and the boiling hot water cannot be pumped from it.

Since the Laing pump is quite expensive at between R2000 and R2500 I'm a bit reluctant to buy another one of then.  The only other real option I could find is the ITS TS510PV 12V DC Circulation Pump, but I could only find it at the unpopular supplier for R724.

Can anyone recommend the ITS pump, or a similar pump or another stockist, preferably in the Western Cape.

Requirements:

  • Needs to work directly from a DC panel 12 - 24V
  • wattage around 10-20W
  • head of about 2.5m
  • flow of about 10l and more per minute

 

Thanks

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