Hi Folks,

About 4 months I got a solar collector plate installed with a 220v (mains) pump to circulate. For the most part it has worked well and at the tail end of summer when it was first installed my geyser didn't do any work for weeks at a time. 

However in the last few weeks I've noticed the pump coming on in the middle of the night. I'm pretty sure this has only just started to happen (as opposed this being a problem from day 1 and I've just slept through it). But as you can imagine, sending lovely warm water from the geyser out to the plate at 2am, and dumping 5 degree water from the plate into the geyser at the same time is not an ideal scenario. 

I've spoken to the guy that installed it and he suspects it's a faulty non-return valve. I'm not sure how this would trigger the pump though. 

Has anyone had any similar experiences and know what the solution is?

Thanks

What is controlling the pump?

The System I use do start the pump when the collector reaches 5 degrees . This stops the collector from freezing . The Geyserwise controller is used .

4 minutes ago, DeepBass9 said:

What is controlling the pump?

A geyserwise system. Mine is set to activate the pump when when the differential between plate and geyser is 7 degrees.  

11 minutes ago, Chris Louw said:

The System I use do start the pump when the collector reaches 5 degrees . This stops the collector from freezing . The Geyserwise controller is used .

Ahh.. OK, this could be a possibility. It has only started to happen now during some very cold nights. 

OK, well that must be the place to look. Where are the sensors? Are they still connected, or broken?

10 minutes ago, DeepBass9 said:

OK, well that must be the place to look. Where are the sensors? Are they still connected, or broken?

There's a sensor in the plate and one in the geyser. As far as I can tell they are still in tact and in their general day-to-day functions, the system works exactly as it should. What I mean by that is, I'll watch it in operation using the geyserwise display panel and everything seems to make sense from a numbers point of view. eg: geyser at 51, plate at 51..53..54..55..56..57..58 (pump goes on, temp in plate drops down to 51, geyser maybe goes up 1 degree).

It just the coming on at night that was a surprise. Chris Louw's explanation makes sense though. Will look that up. 

Edited July 23, 20197 yr by NickM

The geyserwise only has one tank sensor which can be a nuisance . So at night I would check difference between the tank and the solar collector plate, if the plate stays at a similar temperature reading to the geyser I'd look at swapping the one way valve or at lease bang it around a bit  . If not it could be that the controller is trying to prevent it from freezing and thus the pump running in the evening. if you felt the urge to get out of bed when you heard the pump running you could check the two readings and see from there.

14 hours ago, seant said:

The geyserwise only has one tank sensor which can be a nuisance . So at night I would check difference between the tank and the solar collector plate, if the plate stays at a similar temperature reading to the geyser I'd look at swapping the one way valve or at lease bang it around a bit  . If not it could be that the controller is trying to prevent it from freezing and thus the pump running in the evening. if you felt the urge to get out of bed when you heard the pump running you could check the two readings and see from there.

Yeah I have. When it first happened I went to look at the display panel and was wondering why the controller felt the need to dump 5 degree water into the tank and send 50 degree water out to the collector (where it would dissipate off to the atmosphere rapidly!). But the more I think about it (and the more I read the manual!) the more it makes sense that it was protection against freezing. Luckily we don't get too many of those nights in the Boland. 

I had a similar problem. Well, a two fold problem, it turned out to be. The reverse thermosyphen effect was noticed, especially at night, when collector would be higher then tank and pump would switch on. Replaced the two one way valves (which clearly wasn't blocking water) and this all stopped.

The next main problem was that during the day, the water temp would not rise in the tank, and the collector temp would stay very high >100 C. The pump obviously never stops. Covered the EV Tubes with cardbord, to make sure the collector does not overheat, and disassembled the (Wilo) pump to find the impeller in little pieces, actually, most of it was gone!😮.

Replaced the pump and now everything back to normal. System is 7 years old.

PS Anybody know when I can get a replacement impeller? The rest of the pump is still fine. Want to be ready in 7 years time!!

I have a different problem to what is describe above and hope anyone would be able to help me. My pump is not running so my geyser functions as a conventional geyser with the element being the only heat source cause the water does not get pumped to the collector. I noticed that when i disconnect the collector probe then the pump is running. the spanner indicator also lit up green but it gives an E8 error on the Geyserwise showing a fault with the collector probe because I disconnected it. When I insert the collector probe back than the Error E8 disappears but the pump stops then. Any help on how to fix this would help. The temp differential between Solar collector and Geyser temp is set to 7degree Celcius. Any idea of how to fix this problem or what could cause it.