Safety question - should we turn gas off when water is shut off to tank?

[Tom JZ]

Hello - thanks for reading. We are getting a new water heater on Monday. We have an old AO Smith FSG 40 242 gas 40-gallon model that has a small leak (a puddle appears if we're not drawing hot water, and dries up when we do draw hot water). A technician who came out today said there's no way to know if the tank might go, and that it might be smart to shut off the water and gas as a precaution.

My question is: if we turn off the water to the tank tonight, can we leave the gas on pilot so that -- if everything looks the same tomorrow -- we can turn the water and the whole tank back on (just to have hot water for a few hours)? Or is there any risk if we shut off the water -- and the tank bursts and empties overnight -- from having left the gas on pilot? Thanks again.

 

[Reach4]

I think you can safely leave the pilot on if you switch the WH to Vacation mode.

I am not a pro.

There are often discussions as to how long a WH typically lasts. Would you tell us the manufacture date of your old WH?

http://www.buildingcenter.org/ao-smith-water-heater

 

[Sponsor]

 

[Tom JZ]

I think you can safely leave the pilot on if you switch the WH to Vacation mode.

I am not a pro.

There are often discussions as to how long a WH typically lasts. Would you tell us the manufacture date of your old WH?

http://www.buildingcenter.org/ao-smith-water-heater

Thanks for the info. One question - this is an old unit, doesn't have a vacation mode setting. Does that make a difference? Or would setting it to "low" temperature be the same thing?

 

[Jadnashua]

The WH will have a pilot position on the gas valve...just turn it to that and you won't have to relight the pilot (many of the newer ones do not have a pilot). It would only become a problem if the tank emptied after the water was shut off. There needs to be water in the tank if the burner ever turns on. IMHO, if it's going to be replaced soon, and that small leak isn't going to create damage, I'd probably just leave it. A decent WH wouldn't cool off all that much overnight, but if it did, the larger temperature swings might cause it to fail sooner. Well, I guess with a leak, it has failed, but it could get bigger, sooner. It IS safer to shut the inlet off and disable the burner (pilot position on the gas valve) or vacation setting if available. Then, if there's a catastrophic failure, you'd only have the WH tank volume verses an unlimited supply. Still could make a mess, and is one reason why a drain pan can help, but a full-blown blowout could overwhelm even that.

 

[Dj2]

If you are that much worried about a catastrophic situation, why don't you shut off the gas supply and re-ignite the pilot in the morning?

 

[MACPLUMB]

Do not worry about the gas all it does is keep the water in the tank hot, it does not matter if the water is on or off the tank stays full of water