Quote:
Originally Posted by SDMCF
Can you write more about that? I use a Resol DeltaSol BS Pro controller and have occasionally noticed it running the pump when I wouldn't have expected it to. I thought it was something to do with what the manual calls OTC Tube Collector Special Function, where a 2-degree rise in collector temperature causes a 30-second running of the pump, but now you have put a doubt in my mind.
When you say to only turn on above 20C do you mean 20C tube temperature, not 20C ambient?
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The problem is, I have not found a reason for this to happen. A 30 sec run of the pump won't hurt anything. It has to be long enough at -20C to freeze out the water in the other side of the HX and 30 sec won't do it. RESOL has no explanation for it either because the rest of the programming is fine. It is as though the relay sticks and then unsticks later on.
The only way to do it have something in line with the pump circuit that prevents flow if the temp is below 20C (for example). I have heard of other controllers with the same issues going right back to the mid 70s (the first ones I've worked on).