Adding a pump to my sidearm

[mack7]

I am considering adding a pump to my sidearm so I can get quicker recovery on my water heater, just wondering if anyone has done this and if it works better than the thermosiphoning that occurs naturally? Also will it thermosiphon with the pump inline? I was thinking about putting the pump on a timer to just run at peak shower times. Thank you for any replies

 

[Gooserider]

I am considering adding a pump to my sidearm so I can get quicker recovery on my water heater, just wondering if anyone has done this and if it works better than the thermosiphoning that occurs naturally? Also will it thermosiphon with the pump inline? I was thinking about putting the pump on a timer to just run at peak shower times. Thank you for any replies

Assuming that you have hot input water flowing on the boiler side, adding a small pump to the tank side should help, although it may cause you to loose some stratification due to the added flow turbulence causing mixing.

If you keep the same general piping layout, and just add the pump, you should probably still heat by thermosiphoning when the pump is off, as there is supposedly very little flow resistance posed by a non-running circ.

Since you will be exposing the pump to oxygenated water, and it is a potable water circuit, you should use a brass or stainless body pump, NOT a cast iron body - this will cost more, but...

If I were doing something like you describe, I might be inclined to put the pump on an aquastat or other temperature based switch rather than a timer - put the sensor part way down the side of the tank so that if demand is low enough, thermosiphoning will keep the the tank hot down to below the sensor. If the demand gets to be more than the thermosiphon can handle, the sensor will pick up the rising cold line, and the pump will kick on to increase the heat flow...

Another option that might be worth considering is to take a look at the setup that NoFossil has on his DHW, where he uses two mix valves and an extra heat exchanger to pre-heat his makeup water and really reduce the amount of hot that he needs out of the tank.

Gooserider