Willemh

I found that if I tap the NRV a few times in the evening after sun set, the reverse siphoning stops. I all so have a sensor on the cold water return pipe about 1 meter from the NRV, to check why the hot water was cooling down so quickly. I wrote a program on a PIC to check out this return pipe temperature , and when it rises after sun set it will automatically pulse a electromagnet to tap the NRV. I hope it works will let you know.