Hello,
I am just reading your question, unfortunately you may have received a response or figured out the answer to your question long ago but if not a simple reply to you is Watts has a domestic and hydronic expansion tank sizing calculator on their website! If you google watts potable expansion tank calculator and perhaps throw the words “backflow preventer expansion tank sizing” I use this calculator weekly! Hope this helps and sorry for the late reply!
Hello,
I am just reading your question, unfortunately you may have received a response or figured out the answer to your question long ago but if not a simple reply to you is Watts has a domestic and hydronic expansion tank sizing calculator on their website! If you google watts potable expansion tank calculator and perhaps throw the words “backflow preventer expansion tank sizing” I use this calculator weekly! Hope this helps and sorry for the late reply!