NEVER set the water heater temperature to OVER 120° f when using the water directly (no mixing valve) from the hot water outlet of the water heater. This is not a commercial installation, this is a residence, you do not want to cause 2nd and 3rd degree burns do you?
Here is why:
Just thought I would share this with those that do not have it. It’s been useful for me in the past.
It takes over 5 minutes to get 2nd and 3rd degree burns from water which is 120 degrees.
Water which is 130 degrees will produce 2nd and 3rd degree burns in about 30 seconds.
Water which is 140 degrees will produce 2nd and 3rd degree burns in less than 5 seconds.
Water which is 150 degrees will produce 2nd and 3rd degree burns in about 1 1/2 seconds.
Water which is 160 degrees will produce 2nd and 3rd degree burns in about 1/2 second.
The above is from A. O. Smith literature and warning labels.
I was not worried about stagnate water because the two tanks are in series. The water is constantly being changed.
In SylvanLMP’s parallel plumbing setup, the water in one tank could end up never being used, however, that is not the case with the series plumbed system.
[Edited by Jerry Peck on 08 November 2000]