Ball Valves vs. Gate Valves

DEAR MIKE: I had to turn off the water supply valve at the top of my water heater. So I turned it, but it kept on turning and turning without shutting off the water. A neighbor of mine said it is a gate valve and they are cheap. Anyway, I now have to replace the valve. Are there any options for replacing it with the same type of valve? -- Larry O.

DEAR LARRY: Your neighbor is right. A gate valve is a cheaper alternative to a ball valve, although by only a few dollars. Depending on the size, a gate valve costs around $5 and a ball valve is usually under $10.
Both types of valves have the same purpose, which is to control the flow of water. The design of each, however, is vastly different.
A gate valve has a round knob on top that you turn. This motion raises or lowers a gate inside of the housing to stop or start the flow of water. These valves are prone to failure as they age because they can corrode.

A ball valve is a man among boys. Instead of a knob, it uses a lever. This valve has positive stops machined in that allows the lever to move only 90 degrees. When the lever is parallel to the pipe, the valve is open and water will flow. If the lever is perpendicular to the pipe, the valve is closed.
If you were to cut a ball valve open, you would see that the lever is connected to a ball with a hole bored through the center of it. This is where the water passes through. Turning the water on and off is only a matter of throwing the lever 90 degrees.

Because of the round handle on a gate valve, it's hard to tell if the valve is open or closed, and when the valve is broken (like yours), you end up turning the knob one way and then the other without accomplishing anything. In some cases, the gate will corrode and separate from the lifting mechanism and drop. It will come to rest at the bottom of the valve and cut off the flow of water.
The long and short of it is if you are going to replace the valve, spend a few extra dollars and install a ball valve.

You are going to need to sweat off the old valve and sweat on the new one, although you can get ball valves with compression fittings.

Make sure you shut off the main water valve to replace the gate valve (For details on sweating fittings, visit

When sweating valves in place, either remove the valve mechanism from the body or open the valve to allow the heat from the torch to escape and not damage the valve. You can sweat the incoming side directly to the valve. Somewhere after the valve, you will have to sweat in a male adapter, which will connect to the copper flex line.

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