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Header Tank Overflowing

What is the cause of my head tank overflowing

It may be hidden in your loft, but you might not have realised it was there until it overflows and floods your garden. There are many reasons why your header tank might be overflowing.

We have the solution. Continue reading to find out how to diagnose and fix a central heating tank overflowing.

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My header tank is overflowing. What’s the problem?

Your central heating system header tank is important to the workings of the whole thing. It can be found in your loft. It is also known as a cold water storage container. This tank supplies cold water to your central heating system. If the water mains are shut off, it houses the expansion of the hot water tank.

The header tank has an overflow pipe that is connected to it. This ensures that water does not get back into your loft if it overflows. If the header tank is full and your overflow pipe is leaking outside, it is probably doing its job. Your loft won’t flood because water is being safely diverted to the outside.

What’s a central heating header tank?

The F&E (feed-and-expansion tank) is another name for a header tank. It is used in properties with an open-vent central heating unit. It can be found in the loft of most properties at the top of the central heating system.

The header tank in your loft is an essential part of your heating system. These are the functions of the header tank:

  • It is higher than the hot water tank, so gravity feeds it. It acts as a pressure head and pushes hot water from your hot-water outlets to the hot tank.
  • It allows water to escape from your hot water tank’s expansion, which keeps the water level steady in your hot water tanks.
  • It acts as a cold water reservoir in case your mains water supply is interrupted or cut. You can open the top of the header tank to access the water supply. It should not be consumed, as it may be contaminated.

What causes a header tank to overflow?

Your home’s central heating head tank could be overflowing for many reasons. These are the most common reasons that cold water can be seen coming out of your overflow pipes.

Pump overrun

Pump overruns are often responsible for a Header tank overflow. This allows the boiler to pump water even when the central heating or hot water is turned off. This safety feature prevents heat from building up in the heat exchanger.

Because central heating is not turned on, the hot water tank can overflow. This can be prevented by installing an Automatic Bypass Valve into your heating system. The ABV allows hot liquids to circulate in your heating system for several more minutes, even when the valves are closed.

Faulty float mechanism

The float valve mechanism, which looks like a metal or plastic arm, is used to monitor water levels in cold water tanks. When the water level reaches a specified point, it stops cold water flowing into the tank. The ball valve is made up of a metal or plastic arm, and an inflatable ball. It floats on water in header tanks.

If the stop valve isn’t working properly, it will not rise to the correct level and shut off cold-water feed. This allows too much water into the header tank and causes it to overflow through the outlet pipe.

Here are some possible problems that could cause the float mechanism to not control the inflow of water.

  • The ballcock hole, also known as the float, is now formed. It will begin to fill up with water, sinking rather than floating on the surface. Because the ballcock is too heavy, your expansion tank will fill to its maximum level. Any excess water will be forced out of the tank by the overflow pipe.
  • The failure or disintegration of a rubber washer indicates that the float mechanism won’t create a watertight barrier to water inflow. Despite the fact that the water supply has been shut off by the ballcock, the cold water feed will still be open. Water will continue to flow into and out of the header tank.
  • If the brass nipple has become worn, the stop valve won’t work properly. If your water level exceeds the recommended level, your header tank will continue filling.

Leakage or perforation of coils the hot water tank

In the hot cylinder, you will find the loop that heats hot water through the hot cylinder for central heating. The coil transfers heat from hot water to domestic hot water supply.

Over time, the coil may cause a boiler leak and cause central heating water to flow into the domestic hotwater storage area. This can cause domestic water to rise and eventually lead to an overflowing head tank.

The colour of the hot water from your hot taps can tell you if the coil has been punctured. If the water becomes yellow or brown, it is time to replace the coil.

Cold weather freezing

The loft houses the header tank. It is often unheated, making it vulnerable to freezing in winter. The frozen water in your header tanks can cause frozen pipes. To prevent pipes from freezing, insulation jackets can be placed around header tanks and pipes.

Build up of grit and sludge

Dirt and other debris can accumulate on the top of the header tank. This can lead to brown sludge, which will reduce the efficiency of the header tank. Blockages can also cause a decrease in the efficiency of your central heating unit.

The easiest way to remove the sludge in the header tank is to shut off the mains water supply and drain the tank. Next, use a bucket to scoop the sludge. To remove any sludge and debris, you can arrange for a heating technician or heating engineer to power flush your central heating unit.

High water pressure

Overflow could be caused by the pressure in the header tank. If the pressure inside the tank is too high or the ball valve fails to function properly, overflow could occur. Although this is rare, it can cause serious problems. The isolation valve can be used to reduce the water flow.

How to fix a leaking cold-water storage tank

These are the steps you need to take to fix an overflowing header tank. These temporary solutions are only temporary. For a permanent solution, contact Gas Safe registered heating engineers.

Drain excess water from the tank

Overflowing the header tank usually occurs when there is too much cold water in the tank. This excess water should be removed from the tank. Let the hot water taps run for a few seconds. The pressure inside the overflow pipe will gradually decrease until it stops completely.

It is easy to empty the cold storage tank. The hot water tank is continuously fed by the header tank. The hot pipe is used to empty the hot tube and allow cold water to flow down from the header tank.

Draining the expansion tank

Turn off the water supply to the tank by first turning off the mains stopcock or rising main. Next, drain your header tank. Turn on the hot water taps and run the pumps until the tank is empty. Clean up any sludge in the tank. This is the ideal time to do any maintenance on your header tank.

Set the ballcock height and replace it

Check the ballcock to ensure that the water level in the header tank is correct. The ballcock should be about 1 inch below overflow. Adjust it if it isn’t. Bend the arm gently until it is at the right level. Also, make sure to check for leakage in the plastic ball. You should replace the plastic ball if it is leaky.

Make sure you check the overflow pipe

After you’ve done all you can to make sure your backup plan is in place, ensure the overflow pipe works properly for any time the feed or expansion tank attempts to fill up again.

Make sure the ball valve and float valves are working properly and moving freely.

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