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Having trouble heating your home or getting hot water? Repressurising your boiler could be the key to restoring warmth and comfort.
Low boiler pressure can be caused by water leaks or excessively bleeding radiators and force the boiler to shut down as a safety precaution.
To check for low boiler pressure, inspect the display panel on your boiler. Depending on the type of boiler you have installed in your home, you will find either a physical or digital pressure gauge. The dial (or bar) will tell you the level of pressure in the system.
The typical level to aim for is around 1 - 1.5 bar; any less and it is likely that your boiler will need to be repressurised. If the boiler pressure has suddenly dropped, it may be that a major leak in the system has occurred. Check your boiler to see any visible signs of a leek and call a gas safe engineer as soon as possible to fix the problem.
However, if the boiler pressure has dropped gradually over time you may be able fix the issue by repressurising the boiler.
If notice your boiler pressure is too high when your central heating system is on, this is usually something not to worry about. However, if this keeps occurring, it could be that their is too much pressure in your system, the external filling device is faulty or a potential boiler issue.
Always begin the process of repressurising your boiler by checking your boiler manual. Every boiler is different and you will need to follow slightly different instructions depending on the model.
As a general guide, follow these steps:
1. Turn off the boiler. The entire heating system needs to cool before work can be carried out on it.
2. Inspect the boiler filling loop. This is a silver connection between the mains and the primary central heating circuit. One end will have a handle valve while the other end will have an isolation valve.
It can be quite common for the filling loop to leak. Ensure it's securely attached at both ends to maintain optimal performance.
3. Turn the isolation valve anti-clockwise until the line on the valve is directly in line with the pipe. A flat head screwdriver is usually the best tool for this.
4. Turn the handle valve anti-clockwise and allow water to flow through the system, rebalancing the pressure levels.
5. Check the pressure gauge as you do this. You should see the gauge increase as you open the handle valve. Stop once it reaches the recommended level for your boiler.
6. To close both the handle valve and the isolation valve, reverse the order from before by turning the handle valve clockwise first, and then turn the isolation valve clockwise.
7. Switch your boiler on and make sure that everything is functioning correctly, ensuring your home returns to its ideal comfort level.
Not all boilers are compatible with a filling loop; this is particularly true for older combi boiler models. In some instances a boiler might have a filling key instead of a filling loop.
The steps for repressurising a boiler using a filling key instead of a filling loop are slightly different:
1. Turn off the boiler.
2. Insert the filling key into the keyhole and unlock it.
3. Turn the valve next to the key until water flows through it. The best tool to use is either a wrench or a spanner.
4. Monitor the valve until it reaches the recommended level for your boiler model. This will be outlined in the boiler manual.
5. Finally, ensure the valve is securely closed and turn the boiler back on. Once you've securely closed the valve, switch your boiler back on to resume efficient heating throughout your home.
If you have followed the steps above but your boiler’s pressure levels drop as soon as you close the valve, it is highly likely that there is a significant leak. There may also be a fault with your pressure release valve.
In this instance, call a Vaillant installer to inspect your boiler system. Do not keep trying to repressurise the system, as this could potentially cause further damage.
