A ball valve is superior to a gate valve and only costs a few dollars more. So, whenever you have the opportunity to install a valve, it’s a good idea to use a ball rather than a gate. They install in the same way, so really it is silly not to spend a few more dollars and get a superior part.
If you already have a gate valve installed and have to replace it, you can certainly replace it with a ball valve. You will need a torch to heat up the parts and remove them.
Turn the water off and drain it from the pipe and valve. You will want to open the valve as well. Heat up the area where the valve joins the pipe. You can grab the valve with large channel locks or the like to see if it will move. If it does, it is hot enough to remove. You may find it easier to cut the pipe and pull off the valve, otherwise you may heat up a nearby elbow and give it some lateral movement.
Reinstalling the new valve requires that you clean, flux, and heat up the joints so you can solder them. If you have cut the pipe, you can use a repair coupling over the cut and solder that on just like the valve. Always leave the valve in the open position when applying the heat.
A friend called me last night saying he had turned off a gate valve and when he turned it back on it didn’t work. This was the gate valve to the water heater and now the handle just spun around and he didn’t have hot water anywhere. Hint: it’s probably not a good idea to start a plumbing job 8pm if you can get away with it.
So he is panicky and doesn’t have any hot water. This is a classic reason to use a ball valve rather than a gate valve. These valves don’t get touched for years and when you finally need to work on a plumbing issue, you touch it and the gate shears off of the handle’s shaft. The gate won’t lift out and the water is blocked from flowing.
There is a way to get the water flowing again without replacing the valve. With the water off to the entire house, remove the top of the gate valve. This is often easier said than done, as the valve can get awfully crusty. Use a couple of large wrenches and while holding the bottom of the valve still, remove the top half of the valve. Once you have the top removed, reach in and remove the broken gate. Then reassemble the valve and turn the water back on.
The good news is that your water will start flowing again. The bad news is that if you need to do plumbing work at this location again, you will need to turn the water off to the entire house rather than at the isolation valve.
The moment comes when you have to turn off the water to your water heater. You get a ladder to turn off the knob at the top of the water heater and it keeps turning...and turning. Over the years, the valve has corroded and won't turn the water off.
Your choices at this point are to turn off the water at the main shut-off valve in the street (here's how to turn the water off at the street), or you may have another shut-off valve at a different location, such as your garage.
At some point you will need to replace the faulty valve at the top of your water heater. You probably have a gate valve (it's about $2 cheaper than a superior ball valve and that's why the builder installed it), but it is far better to install a ball valve. Here is a discussion on a ball valves vs. gate valves. They both will install in the same manner but the ball valve is far more dependable in a time of crisis.
You will need to break out the torch and sweat the new valve on to the water supply line. Here are details on how to solder copper. Once you have the new valve installed you can turn on the water at the street to test for leaks, and the next time you need to service the water heater, this new valve will isolate it from the rest of the house water supply. That means you can flush the toilets to your heart's content while the water to the water heater is off.
This past Saturday, we received a call from a homeowner that his water heater was leaking. When we arrived, we found that the leak was caused by a fitting and not the water heater itself. Now in order to replace the fitting, we would have to shut the water off. We turned the water off at the gate valve and completed the work. When we went to turn the water back on, the handle just spun and spun. The gate valve had sheared off and wouldn't allow any water to pass. The gate valve would need to be replaced...this time with a more formidable ball valve.
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, 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.
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.