I have a grundfos water circulator mounted on my water heater. I ran a dedicated line from the hot water pipe at the sink furthest from the water heater back to the bottom of the water heater and installed a brass check valve in the line just before entering the bottom of the tank. It seemed to work fine and I unplugged the pump during the summer. I still have not plugged it back in but notice that I still have hot water first thing in the morning at the furthest sink but no where else in the house. The return line back to the tank is hot. I opened up the check valve and it doesn't appear to be stuck. The check valve is installed with the flow toward the water heater. Hot water has to be backing up that return line. I have not replaced the valve, as yet. Any help will be greatly appreciated as no help from grundfos. Thanks

Congratulations!...You created a gravity recirc.

Great! Could you tell me what a gravity recirc. is and what to do about it? Thanks

Okay, I looked up and found what gravity circulation is all about. That must be what I have. However, shouldn't the check valve prevent water from the tank backing up to the faucet? Thanks

quote.."The check valve is installed with the flow toward the water heater"...
this will stop the cold from backing up the hot but do nothing to stop gravity circulation.

If you want to stop it for the summer, install a full bore ball valve on the return line. Other than that, enjoy the electrical savings.

Why would they help, since it is obviously NOT a pump problem. You are describing a problem where the hot water is backing up past the check valve to the shower, but the other faucets have to drain the cold water before receiving hot water.