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Cold water backfeeding up hot water recirc piping
I just came across this issue. Customer recently had an indirect tank replaced. A mixing valve and recirc pump are also on this system. This link gives an accurate depiction of what how it is piped. https://us.v-cdn.net/5021738/uploads/editor/ge/jblsda8f6e4t.jpg
Problem is on a high draw of water, such as the soaking tub, cold water will backfeed through the check valve and recirc pump and up the return piping to the fixture. The recirc pump is powered constantly so I would think it would rule out the issue being as simple as a bad check valve. Do I have a pressure differential problem here, where their street pressure too great for the pump to overcome. Hoping to hear someone has come across this before.