I have a vacation home built in the 50's that has gas service but due to lack of room to run a vent stack they put in 3 electric water heaters. I have two in my main home that are gas units and have had two major floods there because of blow outs that the pan couldn't catch fast enough. These now have a water sensor to shut them off but the oldest of the two is now close to 10 yrs old and I'm getting that feeling that replacing now verses trusting the sensor is in my best interest.

Main house 2 story: Two gas 50 gal each for different areas. Location of units are side by side in a walk out attic above the 1st floor. 1st for master plus 2 full baths. 2nd for kitchen, laundry and 4th bathroom. As far as capacity I get some cool showers in the winter but the current setup is OK. Would like opinions on installing something like the Rinnai RH180 and eliminating the 2nd unit. Also read one of HJ's replys about running two in series so the first catches the sediment so then I could just keep replacing the first one and would keep an eye on anodes if they still put them in. My gas bill is very low so I guess the efficiency isn't a concern but assuming similar water output, my huge concern is water damage. I figure one RH180 would be half the risk of a blow out.

I mentioned the vacation home because I have questions about that also but would like to solve this one first then I can address that issue.

Any advice would be appreciated!!