Hi

Is a non return valve an essential component to the return leg from the pump station to the collector?
My previous install had a NRV in the pump station itself but have just noticed that this is not a feature to the pump station spec to my latest install.
There is little sunshine here at the moment, but is the lack of a NRV going to cause a significant future syphonnage problem when the sun comes out?
Thinking of modifying if I have made a significant omission here ??.
Thoughts anyone?

Thanks

I think it’s there in a standard install, where the tank is below the solar panel, to prevent thermosiphoning all your lovely heat away from the tank into the cold panel and pipe work at night. All winter. Stealing even non-ST heat!

Agree with Tony. I am surprised one is not included in the pumps station unit. I thought when I installed my system there should have been one but it was not immediately obvious. I have a dial temp gauge on each of the flow and return legs and the NRV is incorporated within the temp dial . There are 3 positions that can be located by rotating the dial for commissioning purposes . Is yours like this?.