How are water heaters rated???? Very confusing..

Hi,
I just picked up a 50gal Kenmore 153.332050 water heater.. It is technically pre-owned but was never hooked up, still had all the pipe plugs installed. I think it was tipped over because it has a 4 inch wide dent in the sheet metal on one side at the top and a small crack in the power vent suction. I only paid $325 for it. Best I can tell,it has a .65 EF.. The big fat yellow sticker on the side says I'm going to spend $281 or something like that per year to run it...

How in the heck do they rate these things? Is that $281 for a family of 4 with three girls and a thermostat setting of 155deg??? Or is that $281 for my wife and I with a thermostat setting of 120 degrees?

I'm sure they are using some kind of averaging standard.. does anyone know what math its based on???

Last question: Beyond the obvious sheet metal dent, is there anything I should be concerned about? Do those "glass liners" break if you drop a water heater? Didn't hear anything rattling when we loaded it.

The glass lining is more like a paint that is then heated to crystalize on the inside. Normally, a cosmetic dent on the outside doesn't dent the inner, water-holding tank. There's a layer of insulation between the inner and outer walls...the thing is probably okay. I'd be more concerned about a crack in the power vent. If it fell on a plug sticking out, that may have cracked the lining around it. Are they all still sticking out straight?

You can go to the government website (listed on the yellow tag) to read the test procedure. It is for a 'typical' family and use. Just like any average, few people match the average.

Depending on where you live, you may be required to install a tempering valve on the hot water outlet. And, if you're going to think about running it at 155, you MUST do it for safety purposes. Both a tempering valve and a vacuum breaker are required on any WH install where I live. This can add some extra costs and complexity to the install if yours does not currently have these.

Thanks for the info. Michigan does not require a tempering valve so far as I know and I only plan on running the water at 115 to 120 anyhow.

The EF test conditions spec the storage temp at ~140F in a room that averages 67.5F, and a water volume use of 64 gallons/day, every day, with an incoming water temp of 58F. Your storage temp, room temp, incoming water temp, and water use volumes will vary.

The big yellow label usually specifies the kwh/year or therms/year as well as a dollars/year, and gives you the presumed $/kwh pricing or $/therm pricing behind the dollar number. Your gas / electricity rates will also vary.