fixmyplumbing

Simple explanations for plumbing problems

Ball valve passing in tank

There are any number of kits available to replace the innards of a ball valve.  Personally I don’t bother with them, I always just replace the whole valve the price isn’t that much different and it saves future problems.  Follow the steps below to replace the valve.

  1.  Take the lid and insulation from the top of the tank. Look in and make sure you are changing the right valve.  Its the right one if the water level is above the overflow level.
  2. Turn the water off to the valve.  Every float operated valve should have a small valve before it so the water can be turned off generally using a flat screwdriver.  If it isn’t there just turn off the whole house using the stopcock.
  3. Push the ball down to release the pressure in the pipework this will also serve to reassure you that when you disconnect the pipework no water is going to come out.
  4. Lower the level of the water in the tank either by opening a hot water tap downstairs (for hot water feed tank) or by scooping out into a bucket (from the central heating fill tank).
  5. Using a set of pliers and a spanner hold onto the valve and turn the compression nut with the spanner.  Take all the way off and slide down the pipe a few inches.
  6. Unfasten the two flat nuts holding the valve onto the wall of the tank and feed the valve into the tank and then dispose of it.
  7. On the new valve tighten all the nuts up on the body of the valve before its installed and attach the ball float remembering to secure the float by tightening up the screw. The float should be low enough that the water level is a few inches below the overflow level.  On the small central heating tank you may have to bend the arm of the valve so the level is lower to allow the water level to rise when the heating is on.
  8. Screw one of the flat washers all the way down the thread of the valve.  Now push the threaded part of the valve through the hole in the tank.  There is normally a rigid rectangular piece of plastic to support the tank, push this over the threaded part of the valve.  Now thread the second flat nut onto the valve and tighten up both nuts  securing the valve to the tank with the spout on the top and the ball and arm free to move up and down.
  9. Now look at the water supply pipe.  It will either have a nut and olive or a 1/2 inch tap connector with a washer.  If it is a nut and olive push the pipe into the valve up to the olive and tighten up remembering to hold the valve in the upright position with a spanner or grips. If it is a tap connector and washer dig the old washer out and replace with a new one. Push the tap connector so it is sitting square of the threaded part of the valve and tighten up the nut.  When threading the nut onto the vale be very careful to avoid cross threading.  If it feels like it has gone tight a lot earlier than you expected stop and check that it is on the thread square.  Not checking this can ruin both the nut and the valve so its better to be cautious.
  10. The only thing left is to turn the water back on.  Turn it on gently to start with so its easier to turn off if the joints leak.  If the joints outside the tank are sound let the tank fill up to its natural level.  Don’t turn off the water by pulling the float up.  This can give you a false reading about the water level. You may have to adjust the level of the float on the arm to give the right water level.

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