SylvanLMP
In reply to message posted by Homeowner:
Just purchased older house with 2 water heaters connected in series. what should the settings be? Should the first heater have a higher or lower temp? I would think that the correct way would be to have the first tank at the lower temperature than the second tank. Please advise
You heard from the rest NOW listen to the BEST (ME) 
Setting in “series” the 1st heater would PREHEAT the water for the 2nd and final heating.
The theory behind this hook up is not to KILL both heaters as neither one will have thermo shock of very cold water entering a hot tank plus much less condensation.
Figuring cold water supply is 40 degree F. and being heated to 90 degrees then the 90 degree water is then heated to 125 in theory neither tank is going to labor very hard making hot water. This saves lots of therms and latient ASK Harold LOL
Now for a better way to hook up heaters In my professional opinion.
Have a professional hook up these tanks in parallel with everything being equal.
The way I hook these things up when I need a lot of volume FAST like peak demands for an apartment building or whirl pool installation is as follows
I install all piping equal lengths and have the cold water lines fed through a 27″ heat sink loop as there can be no cold water stratification more then 27″ down these type of installations ( I DONT NOT USE DANGEROUS CHECK VALVES)
I place a temperature gauge on the hot water discharge of each heather and use a globe (balancing) valve to fine tune the temperature so both discharge are the exact same temperature to a common header
Now Here is what we professionals do that separate us from the tract house mentality.
WE install a Holby Mixing Valve BUT just before we temper this water we take the 140 -160 degree HOT water and send a dedicated line to the following fixtures 1 line goes directly to the residential dishwasher to kill all the bacteria.
NOTE commercial dishwashers requires 180-200 degrees in lieu of chemicals for disinfection.
We take the hot water 140+ and use it in the DOMESTIC washing machine (clothes washer) again to make sure bacteria is going to be snuffed out.
Now we temper the remainder of the hot water to around 125 degree to kill most of the regular house hold bacteria that can be found on lower temperature systems like that crap under slab heating which can be an incubator for all kinds of great diseases.
It is alsp advisable to instal a temperature guage on the mixed ( tempered) temperature piping header right after the Holby.
Now because people today are no longer responsible for being stupid we have to protect them from themselves by way of temperature and pressure balancing valves located at the basin, shower, bath tub and any other place a moron can get burnt.
We also use a “Just right” from Nibco to have return circulation without the need for a circulator.
There are lots of games the real professional can do with hot water tanks in series or parallel or even a “bridge circuit” using both of these combined tricks of the trade a “real plumber” can do.
Hey Have a great One now you have options…
Just kidding Mates you blokes are great
