Hot Water Tank: Reverse Return

Hilly

When doing reverse return with water heaters are there considerations to take into account? I know when you do cascading parallel piping everything has to be perfectly equal. I am going to look at a project that may want the option for a 3rd tank down the road and reverse return seems like the most logical solution for tidiness and future expansion purposes.

Mark Eatherton

Size pipes based on connected flow. In other words, if the cold supply is 1" and tappings are 3/4", then cold starts out 1" until first 3/4" drop, then 3/4" to second tank. Pressure drop through both tanks must be the same, or as close to same as possible.

Hot starts out 3/4" then jumps to 1" once it picks up the second tank. If piped as shown in your drawing due to piping being held so low, if one tank fails, you will have to shut off all tanks in order to replace the bad one.

Hold all piping, isolation valves etc higher than the tops of the tanks, with unions on the drops high enough to allow isolation and removal without to interrupt the operation of the non affected tank. It's not going to cost a whole lot more money, but will make future service and replacement for whomever has the task.

If pressure drops through all tanks (you can parallel as any tanks as you want) are the same, on draw, all tanks will see the same flow through their respective tanks.

ME

Mark Eatherton

Some examples. Piping was not held high in drawing for drawing clarity's sake.

hot_rod

a few options, the low lead QuickSetter can balance multiple tanks and save piping. It also shows flow rates. These are indirect tanks with piping options on both coil and tank.

Ideally with RR you should step the piping for perfect balance.

Good info in Idronics 17

Hilly

Thanks guys. I'll get some more info today about the project.