Check out some similar questions!

SD86 · Sep 27, 2007, 09:10 AM

My bathtub hot water faucet has a leak, and I cannot find any valve to turn off the flow to the faucet. If I turn off the water to the hot water tank, would that damage the tank or cause other problems?

Ken 297 · Sep 27, 2007, 09:14 AM

This will not cause damage.
You can shut off the water supply to the hot tank.
If you have to drain the hot tank and leave in turned on this may cause a problem but just to shut it off to make a repair is not a problem

SD86 · Sep 27, 2007, 09:17 AM

So if I turn off the supply, the tank will not drain?

labman · Sep 27, 2007, 09:41 AM

Water expands and contracts with temperature change. Never follow the above advice without opening a hot water faucet at once. Water must always be free to flow in and out of a hot water tank. In most cases, if you promptly take the hot water faucet apart, you would get away with it by giving the water a place to go.

When you do take the faucet apart, all the hot water in the lines above it will flow out. If you took the faucet apart in a laundry tub next to the hot water tank, water would flow out until the level dropped to that of the faucet. If the faucet is above the tank, it shouldn't drain.

SD86 · Sep 27, 2007, 09:50 AM

I appreciate the answer so far, but let me re-ask the question:

If I turn off the inlet to the hot water tank (but not the outlet, I can't find that... ), will the tank drain out via the bathtub leak?

The hot water heater is a Kenmore Power Miser 9 (40 gal). The hot water pipe comes out of the top of the tank, but I don't know if it is internally running from the bottom of the tank to the top, or how the pressure would work if I turned off the inlet. I'm thinking that with the inlet off the water should not flow out of the tank, and therefore the tank won't go dry. Also, I have an expansion tank on it.

Also, for kicks and giggles, assume that it would take some time (days) for a repair to be done

Am I right or wrong? And is it safe to turn off the water inlet?

caibuadday · Sep 27, 2007, 04:51 PM

Originally Posted by SD86

My bathtub hot water faucet has a leak, and I cannot find any valve to turn off the flow to the faucet. If I turn off the water to the hot water tank, would that damage the tank or cause other problems?

First turn off the gas/ electric? Then close the inlet water valve, open the leaky faucet ( don't open any hot and cold at the same time) , then open the faucet(hot) before the leaky one, all these may not drain out the pipe then uoy have to open more hot faucets. I f your pipe is rusty, remove the screen/aerator on the faucets, because when you turn on the water debris would come out for about 10 min

labman · Sep 27, 2007, 06:55 PM

The water won't drain out of the tank if the bath tub is above the hot water heater. If everything is on one floor, the water may drain down to the level of the faucet.

You don't have to worry about opening the hot water faucet if the expansion tank is between the shut off and the hot water tank.

You do want to make sure the gas or electricity is off unless the tank is completely full.

Fr_Chuck · Sep 27, 2007, 07:10 PM

And while working on it, consider putting shut offs on each item, bath tub, toliets, sinks should all have individual shut off.

But as labman noted, it is best to shut off the power to the hot water heater, you would not know the number of damaged heating elements from running dry.

SD86 · Sep 27, 2007, 07:35 PM

Thanks to all for the answers. I've shut the temperature knob down to the "pilot light" setting, turned the top switch from "on" to "pilot", and am turning the inlet water valve off. From what I've read, that should be sufficient and shouldn't burn out any heating elements.

If I'm wrong, please warn me now...

Nutter butter · Sep 27, 2007, 11:47 PM

NO it won't. If the inlet and outlet is at the top.

labman · Sep 28, 2007, 03:40 AM

That is OK if the expansion tank is, as it should be, after the inlet valve.

If you follow Bishop Chuck's suggestion on adding shut offs, make them ball valves. They are easier to work, give a tighter shutoff, and leak less.

labman · Oct 4, 2007, 08:41 PM

Since you have an expansion tank, it will be OK Water or air must always be free to flow in and out of a hot water tank to accommodate temperature changes. Ken 297 is not only wrong, but dangerous to suggest just shutting the inlet off without knowing you had an expqansion tank. One more reddie from somebody whose dangerous advice I criticized. The people coming here for help would be better served if more questions were left for somebody that could give a good answer. I seldom answer plumbing questions unless I see a bad answer like Ken's

The air in the expansion tank will push water out until air reaches the outlet.

Ken 297 · Oct 5, 2007, 04:27 PM

Can you explain how this is dangerous in any way?
If you shut off the valve before the tank and water expands the expansion will be taken up at the leak in the bathtub. If you shut off the water after the tank expansion will be taken up through the inlet side of the tank.
If you shut off both sides of the tank the water is already hot,so expansion will be minimal. In the unlikely event expansion causes pressure to build up that is what the pressure relief valve is for.
If you are worried about water draining from the tank without the power being shut off I shut off literally thousands of hot water tanks a year with the power left on and have NEVER had a problem.
I honestly don't understand what the concern is in my answer. If I am missing something in the original question let me know.