How to bleed a central heating system Combi boiler?

What are Combi boilers?

Combination boiler or combi boilers come being one of the most common types of boilers used in UK for a reason. Unlike the system and conventional units, the combination boilers are designed to be an all in one unit which produces hot water for taps and central heating in order to cut down the use of storage tanks or cylinders, thus occupying the least space required to house the boiler. Additionally on a comparison, the installations are much easier and faster than any other boiler unit.

The combi boilers operates by using the water from the main supply that results in stronger water pressure and ensures that you would never be lacking on hot water again. The modern highly efficient units come, being a stainless steel condensing boiler with an inbuilt heat exchanger that operates in order to serve the customers with hot water immediately.

There are two main reasons behind the combi boilers great and powerful efficiency i.e. these units have high operating efficiency and low internal water volume. This means when in summer days you don’t need space heating you are only paying to heat water which is domestically required.

Now that you have a well knowledge about the combi boilers, you might be thinking about how to bleed a central heating system combi boiler?

Why bleeding?

The infiltration in your heating system can reduce the efficiency of your unit, turn your radiators cold and produce abnormal sounds like whistling or humming, demanding an urge to bleed your central heating system.

If you find your system pressure to be too high then releasing some of the air out of the system would likely solve the problem for you and put the pressure down to a required level.

In case of the combi boilers, the hot water circulates between the radiator and the boiler through pipes. Over the time, the air seeps into the pipes, creating air bubbles which then interfere with the distribution of water in the pipe and the vessel, thus reducing the efficiency level of your system and generating huge energy waste which certainly increases your energy bills. 

Bleeding the system would, therefore, allow a good circulation of hot water in the pipe lines, and would eventually result into uniform heat diffusion along with a cut down on your energy bills.

Now that you have a clear understanding of why bleeding comes being important for your system, let us discuss about how to bleed a central heating system combi boiler?

How to bleed a central heating system Combi boiler?

The accumulated air in your boiler can be removed by following these easy steps-

1. Depending on the type of bleed valve in your system, you need to undo it using a radiator bleed key or a flat screwdriver.
2. Now put the boiler system off in order to allow the air to rise to the top of the radiator and prevent it from interfering during the process.
3. Use a pair of grips to ensure that the valves at the bottom of your radiator are open in order to allow the water to flow into the radiator.
4. Now loosen the radiator’s bleed valve with a radiator key or a flathead screwdriver.
5. As soon as you loosen the bleed valve, you will be able to hear hissing sound of the air escaping.
6. Once the water begins to come out, you know that all the air has been released from the radiator. Now tighten the bleed valve back.
7. It is recommended to keep a cloth ready for any droplets that would come out of the system as soon as the air escapes.
8. Now go around each of the radiators in the house, repeating the process if required.

Warning- It is highly recommended to consider a professional help if you have no experience about it, as it can be dangerous dealing with water flowing with a lot of pressure.