Water Heaters - Series reconnection

I have two 50 gallon gas water heaters in the attic. One is about 15 years old, the other was recently replaced. Each serves part of the house, but we really don't need that much capacity. Instead of replacing the second water heater, I was going to just reconnect the new one to service both circuits (they are installed next to each other). Then I had a random thought. The older water heater isn't leaking (yet) but since it is in the attic (which gets good and hot during the summer), would I save a bit by connecting the two in series with the gas to the first (older) water turned off. My thinking was that the first water heater would rise to the average temperature of the attic - maybe 100 degrees - and that would "preheat" the water going into the second water heater. I could measure inlet and outlet temperature to see if there really was a benefit.

Thoughts? Comments? Suggestions?

(Or should I just reconnect the newer heater and toss out the old one?):weird:

I think that is good thinking! I suggest that you plumb in isolation valves on the old heater, so if it does start to leak it would be easy to isolate & bypass it. Also consider removing tank insulation. Make sure the gas line is properly disconnected and sealed off.

I have seen such setups and they work well. If your water consumption is not demanding, you may even get by with "pilot only" operation during the summer.

However, I have a big problem with a 15 year old water heater in the attic. Consider the potential damage if, correction, WHEN it starts to leak. All water heaters will leak (it even says so on the label), it's just a question of when. How lucky do you feel? Don't count on the little pan with the little pipe attached to it to protect you from flooding. It may handle a small leak but not much more. And, little leaks turn into big leaks before you know it.

Good luck.

On reflection, it was a good idea - but no. Thanks for the reminder about the 15 year old water heater. After thinking about that, I just reconnected the plumbing for a single water heater, drained the old one, and now neet to remove it.

Thanks.