WhiteS2k

Give us some details please: How much for the heater (what size); how much for installation; and how long is the warranty? (Also, how old was the unit that failed?)

S2KCDN

I use the Rennai brand and sometimes the Navien on demand hot water for most of the houses I build. The Rinnai units do not require an out of-the-ordinary gas meter and you never run out of hot water. You save 40% energy costs over a conventional gas hot water tank and they last twice as long.
The navien costs more but lasts longer and is even more efficient.

In my own house I had 60 gal. natural gas hot water tank and changed it out for a Rinnai on-demand heater works just fine but there are some little quirks that you adjust to.

Capital costs are higher but the operating costs are way down with tankless water heaters. Depending on how much hot water you use everyday equates to the amount of your savings.

I suggest that there are merits to these systems that one should consider when it comes time to replace the old hot water tank.

Matt_in_VA

The only thing that I have to add is this:

If your water heater is electric and you have well water or municipal water that is hard go for "low density" electric elements. We use to be on well water that was "rock hard" with a lot of minerals in it. Our water heater would burn up an element about every fifteen months. I finally discovered "low density" electric elements that are designed to deal with hard water and they lasted years.

Just my two cents. I hope that this may be helpful to someone.

dlq04

Our direct-vent American (brand name) w/h is 15 yrs old and going strong (knock on wood). We have well water and have never replaced anything. Perhaps the water softener makes the difference.

Filthy Beast

Dean. the old one 's were not worth a damn . My mother and father in law had one it was a total waste of money. We have a Rinnia propane unit, its quick and we never run out of hot water, uses gas only when you want hot water.

Legal Bill

I currently have a State power vent gas water heater that failed after about 12 years. The A.O. Smith I am buying is the current version of the very same heater. A.O. Smith makes the State brand. The power vent adds about $300 to the price of the heater.