On what plumbing projects does water heater need to be shut off?

[petrie]

When I installed my 40 gallon power vented natural gas water heater the directions for filling it said to open all the hot water faucets to get air out of system and not to turn the water heater on until the tank was completely filled.

I've read that electric water heaters definetly need to be shut off if draining because the heating elements can over heat if they don't have water around them.


My question is: Does the Water heater need to be turned off for all plumbing projects? If I'm doing some soldering on a basement pipe I will empty several gallons out of water heater to clear water lines. So, in that case I figure it needs to be shut down.

Twice recently I have replaced shower valves for two seperate people and I shut there water heaters off and didn't turn them back on till all the air was out of hot water lines. Not such a big deal on an electric or power vented heater, but on a natural draft with a pilot light it's kind of a pain.

 

[Terry]

Twice recently I have replaced shower valves for two seperate people and I shut there water heaters off and didn't turn them back on till all the air was out of hot water lines. Not such a big deal on an electric or power vented heater, but on a natural draft with a pilot light it's kind of a pain.

We turn off electric water heaters at the breaker box.
I don't worry so much about a gas water heater. We have sometimes turned them to the vacation setting if we think it's going to drain very much. If we do sense it draining, we can loosen a flex connector at the incoming to break the siphon.
When we do a shutdown, we open all the faucets and showers in the home, on all of the floors.
When want a complete draindown, and we don't want to wait a long time for it.

 

[Sponsor]

 

[petrie]

I hear you on the opening every faucet for complete drain down. I forgot to open two outside faucets when doing my water heater and I had to wait forever for water to stop, then it would start again, etc. Vaccum in pipes screwed me up.

So, inregard to siphoning of water heater. It is something that may or may not happen? Circumstances have to be just right for it to happen? Just from playing with a bowl of water and a piece of rubber tubing I see the siphon principle in action. Is cracking the cold water inlet faster than letting the water heater siphon itself down to the anti-siphon hole in the dip-tube? I suppose on an old water heater the hole in the dip tube could be clogged with minerals.

 

[Jadnashua]

It depends on where the WH is...everything on a single story, one issue. Some put it in the attic, much bigger difference. In the basement, and you're working on something upstairs, not going to happen unless you open a faucet down there.