I have a recirculation pump with a dedicated return back to the water heater. I hheard about a new type that recirculates using the existing cold water line. It still uses the pump but eliminates the return hot water line to the heater. Does this new system work well and if not what are the drawbacks. We are on a septic system so I like to eliminate the wasted water waiting for the hot water to reach each tap. Thanks

And here you are, (see image). To check out cold water return recirculation systems click on; Hot Water Circulating Systems - Cold Water Return (http://www.chilipepperapp.com/cwrcs.htm)
Good luck and thank you for rating my answer. Tom

Yes, Tom nailed it. This system was developed by LAING. Pump has built-in timer and has thermostat. It automatically activates when water temperature drops bellow 96 degrees F. Than, it activates and draws hot water to the fixture.

This system works best if you have your plumbing fixtures "in-line" from the water heater - as shown in Tom's drawing. If you have fixtures to the left and right of your heater than you would have to install 2 pumps. Now, in the worst scenario: if you have irregular house with fixture all over then you would have to install more than 2 pumps to satisfy each outlet. These pumps run about $300.00 a pop.

Nowadays, there are other manufacturers with similar products. But all these pumps are considered to be retrofit. If you have recirculation loop in walls already - than you have the best system installed. Why change it..