yes..series....my bad......least I explained it correctly. I have two 50 gallon in *series* Mitch Miller wrote: alan smith wrote: > Having designed and built my house, pretty much everything I wanted...I got. > eventually adding. Conduit to the attic, 2" conduit min. Use at least 2 water heaters > in parallel (pre-heat...and main draw). Wouldn't that be in series? The output from the pre-heat feeds the main heater, right? Our neighbors have that and they *REALLY* like it. He says they NEVER run out of hot watet. And, because the first one is not heating the water ALL the way, you don't lose as much energy to the room. -- Mitch -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --------------------------------- All-new Yahoo! Mail - Fire up a more powerful email and get things done faster. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist