Has anyone had any experience with the systems that have a small pump at the hot water heater, a check valve located at the ****hest sink and use the cold water pipes to return the warm water. A popular brand is Grundfos. Questions:

When you turn on the cold water tap, do you get warm water? If so, for how long.

If you drink from the cold water tap are you getting ANY water from the hot water heater tank? - UGH!