I am going to add a 50 gal tank to an existing 40 gal tank for new bathroom. Both tanks are gas, what is the best way to connect them?

Hi Jesseman,

Usually, you will see two water heaters piped together such that:

Cold water into cold inlet heater 1, hot water out of heater 1 gets piped into cold inlet heater 2, hot outlet heater 2 goes to house... called piping in SERIES.

OR

You could also pipe separate colds into each heater and have separate hots come out and join to feed the house... called piping in PARALLEL

Check out this article for more info.:

http://www.aaronsinspections.com/Water%20Heater%20Plumbing.pdf

Either way, you may want to plan on installing extra shutoffs in system (such as shutoffs on hot water pipes, too) so that you can ISOLATE either water heater if one should leak. That will make it less of an emergency to replace when you need to in the future.

Let me know if need more information...

Mark