Service valves are used to isolate sections of the plumbing system to allow for repair and maintenance. Knowing how to repair or replace a valve will save you money and get you out of trouble in an emergency.
There are many different valves used in domestic plumbing including gate valves and ball or isolation valves. Gate valves are commonly found on the cold water pipe coming from the cold water storage cistern in the loft. Isolation valves are commonly found on pipework going to appliances such as washing machines and wc cisterns.
In order to carry out work on one of these valves, you will need to switch off the water and drain down the appropriate section of plumbing.
What Does An Isolation Valve Do?
An isolation valve is a valve that halts the flow of water into a part of a water pipe system. This valve allows you to isolate one unit in a system, such as a toilet or a sink, from the main water supply.
Say you want to do some plumbing work on your toilet. You’ll need to cut off the water to the toilet without affecting the rest of your house. An isolation valve allows you to do this. The valve is positioned on the feed from the main supply, and closing it will stop water from reaching your toilet.
In a plumbing emergency, you’ll need to shut off the water quickly. You can shut off the entire supply to your house or, through an isolation valve, just to the sink or toilet. In any case, valves should be regularly lubricated and checked. You don’t want to discover that the valve has rusted shut and you can’t turn it off.
The Problems with Isolation Valves
Of course, it’s too easy if isolation valves were without their problems, right? It’s just another facet of being a homeowner.
Can Isolation Valves Leak?
Yes. Various types of valves are prone to leaking, especially cheaper ones. The valve’s parts wear out faster.
Can Isolation Valves Fail?
Again, yes. Your valve has both a screw or a handle, and both can fail as time goes by.
Why Is My Isolation Valve Leaking?
If your isolation valve is leaking, you may have a loose connecting nut or a broken valve component. Take the ballofix valve, for instance.
Ballofix valves are very common types of isolation valves. A ballofix valve isolates the water supply by turning a screw. When you turn the screw to the off position, a ball goes across the pipe and stops the flow. Turning the screw back to the on position starts the flow again.
Locating the Olive
Imagine that you want to replace a tap on your kitchen sink. After you replace it and turn the water supply back on, you notice that there is water leaking from the screw. Most likely, the screw has ruptured the water-tight seal (called an “olive”) within the valve.
How Do I Stop My Isolation Valve From Leaking?
Under normal circumstances, a leaking screw is either set to fully open or fully closed. Gently turn the screw a few degrees to the right or left. This may be enough to reseal the valve.
Sometimes a leaking valve will reseal itself. Tape up the leak or put something under it to catch the water. Leave it for a few hours, then check to see if it is still leaking.
Both of these fixes are temporary, however, and you will eventually need to replace the valve.
Leaking Gate Valve or Isolation valve
There are two common examples of leaking valves. There may be water leaking from the spindle on a gate valve or, on both gate valves and isolation valves, there may be a leak from the compression nut where the valve is connected to the pipework.
Leaks from gland nuts – the small nut at the base of the spindle – can often be resolved by tightening the nut a little. To do this, you should hold the body of the valve with a wrench to prevent it moving, then use a spanner or second wrench to tighten the nut. If this fails to stop the leak, you may need to repack the gland nut, or simply replace the valve.
Where there’s a leak on one of the joints with the pipework, you can sometimes cure this by nipping it up a little. Again holding the valve with a wrench to prevent it twisting and making the leak worse, use a second pipe wrench to tighten the compression nut a little. Don’t overdo it though as excess tightening can damage the olive and make the matter a lot worse.
Replacing a Service Valve
Replacing the valve is not a complicated job. But before you do any repairs, turn off the water supply. If the leak cannot be stopped, you will need to refit the valve or if the valve has seized altogether, you will need to fit a replacement.
1 – Purchasing a Replacement Valve
When buying a replacement, make sure that the replacement you purchased is the same size as the original so you won’t have to make any changes to the pipework. Replace the valve, and it’s good as new!
Some valves are directional so before removing the old one, make a note of the direction of flow so that you can fit the new one the same way round.
2 – Undoing the Valve
You will need two pipe wrenches or a wrench and a spanner to suit the size of the compression nut. Hold the body of the valve to prevent it from twisting and exerting pressure on the pipework. Use the second wrench, or spanner, to undo the compression nut.
Repeat this on the other end of the valve and gently ease the valve away from the pipework. The fitting is often quite tight as the pipe sits inside the valve at both ends and there’s not much play.
Removing the Olives
With the valve removed, you now need to take the olives – rings mounted over the pipework – off the pipes. Olives are squashed tight against the pipe in a compression fitting so they may be difficult to remove. The first option is to use a gentle grip with a wrench and rotate them a little as you pull them off the pipe.
Cutting the Pipe
If that gentle grip doesn’t work, you’ll need to cut them off. Use a junior hacksaw and cut through the olive at an angle being careful not to cut or damage the pipe at all. Finally, clean up the pipe ends using a wad of steel wool.
3 – Fitting the New Valve
Hold the new valve next to the pipework to ensure that no adjustments are needed and that the pipe both sides will sit into the valve the correct amount. If you look inside the end of the valve you’ll see an edge where the pipe should stop.
Adding the Olive
Slide the compression nut onto the pipe followed by the olive and do the same for the other end. Fit the valve onto the pipework – this may require a little work as there’s often not much play in the pipework. With the valve in position, double-check the flow direction.
Tightening the Compression Nut
Hand tighten the compression nut on both ends. Hold the body of the valve with a wrench to stop it turning and then tighten the nut at either end. This tightening process compresses the olive around the pipe to form the seal. When the nut feels moderately tight, give another half turn to fully tighten but don’t overdo it.
Remember, you can always nip it up a bit but if it’s overtightened you’ll be back to square one. Sometimes a poorly fitting joint can be sealed by wrapping PTFE tape around the olive to improve the seal – note, PTFE tape isn’t used around the threaded section.
4 – Switching the Water On
With the valve in the closed position, turn the water back on and inspect your work for leaks. If all looks ok, open the valve and check again. Once you’re happy you’ve done a good job, make sure all supplies are working properly and that there are no airlocks in the pipework.
No one likes a leaky valve, especially when it’s an isolation valve. But with proper maintenance, you can increase the valve’s life and delay the day when you’ll have to replace it.