Hi all, 

I've got a solar geyser system installed using pumped system from collector to geyser. 

My issue is that I'm losing >20 degrees geyser temperature overnight without using any hot water.

My current theory is that the pump is circulating hot water to the panel,so the hot water does not stay in the geyser and gets cooled down when circulating in the panel. 

When I do heat the water up at night I notice that the collector temperature goes up as well to match the geyser temperature and then when switched off I lose more than 20 degrees temp in both geyser and collector overnight without using any hot water.

Is this a faulty installation? Should the geyser be pumping hot water to the collector like this?

Hi,

It is most likely you pump contoller that is going into "freeze mode". When the temp reading at the panel goes lower than 5degrees hot water from the geyser is pumped to the panel to prevent the panel freezing. If you have EV Tubes you can disable this function. For flat plates it is needed.

@CtUser,

I've experienced something simular, and it was due to one of the one way valves going faulty - the hot water affects the spring functionality, so the flap doesn't close, and the water flows in the wrong direction.

Was fixed after I replaced (both) the valves. Seems like these valves don't like the hot water that comes from the collecter, and fails in about 5 years. Next time i will actually try and relocate the orientation of the valve, so that it is not in a horisontal position any more, hopefully gravity will assist to keep the flap closed natually. when the spring collapses.

Does your installation use the Geyserwise controller?
If so, then change your setting so that the panel temp only activates the circulation pump at 0C. I think it defaults to either 7 or 10C.
I found that my panel temp sensor underreads by about 5C, so it used to pump the warm geyser water even when the real panel water temp was close to 10C.
Now that it's set at 0C it still does it at a real approximate 5C. But that made a huge difference.
Else consider an inline switch on the 12V pump conducter that you can switch off at night when you know there is no chance of Frost.

I have a geyserwise controller and have noted that the LED in the main board corresponds to activation of the DC pump. My problem is that the LED goes off after equalising temperature BUT the pump keeps going. It seems like the relay is staying engaged?? Any ideas?