I do not have a vacuum relief on my solar panels but have now decided that I should have one .
I phoned my friendly neighbourhood pool store to see if they carried these. " No we don't install solar panels so we don't carry the components"
Do you k now who does install solar panels around here?.... No.
Thanks for all your help.
I phoned a plumbing supply house and asked if they had a 3/4" vacuum relief . They do not but they do have a 1/2" in stock.
Has anybody used a 1/2" relief valve or can anybody see why it should not work?