hot water recirc loop

installed a gravity hot water recirc loop and now it seems my hot water supply runs out much faster than it used to. I have the pipe insulated, it is 3/4 inch all the way back to heater. do I need to install a check valve, or what? The hot water comes almost instant but runs out too quick. can anyone help? Thank you.

Without a check valve at the heater, the cold water in the bottom of the tank will backflow and give you cold or cool water at the faucet.

installed check valve at heater, everything ok now, thanks.