Expansion vessel how does it work

Another warning sign that something is wrong with this central heating component is if water escapes when you press on the valve. This may just be condensation, which can be drained from the Schrader valve. Draining and recharging the vessel should always be attempted prior to calling the manufacturer for a suspected failed vessel.

You will need appropriate measuring equipment to test this. For example, you could use a car tyre pressure gauge pictured below. If you discover the pressure is too low, you can recharge it using any type of air pump and attachment. You can do this by simply putting some washing up liquid over it.

If you see bubbles forming in this liquid, you may need a replacement valve. Welcome to Viessmann United Kingdom! It looks like you might not be in the UK? The products and services presented on this page may not be available in your country; find your local Viessmann website below. Viessmann United States. Answer a few questions and find the heating system that's best for you.

Find a product, get a quote. How to Bleed a Raditor. Watch the Video. Product Registration. Find a new boiler. Heating Advice. Homeowners Professionals. What is an expansion vessel? How does it work? Where is the expansion vessel? We can all point to one important component — the boiler. But other critical constituents of this process fly under the radar. None more so than expansion vessels.

To highlight the importance of expansion vessels , we have put together this hopefully illuminating post. Expansion vessels consist of a small steel container divided into two parts by a rubber diaphragm.

One side of the rubber is filled with air or nitrogen, while the other is filled with water. The rubber diaphragm, on the inside, possesses an extremely low permeability which not only serves to contains pressure loss, but also helps to ward off corrosion.

Even in a single day, our home can go through many, many heating cycles. As the water gets hotter it expands and the pressure in the water side of the expansion vessel increases.

The increase in pressure on the water side of the diaphragm causes the diaphragm to distort, compressing the air and absorbing the expansion of water within the sealed system. When the water cools the pressure reduces and the diaphragm returns to its original shape. Most vessels are fitted with a bicycle tyre pump type adapter to allow recharging. Eventually the diaphragm may rupture, allowing water into the air chamber.

The remaining air is then forced out and the expansion vessel ceases to work, allowing the water in the system to over-expand and trip one of the other safety devices on the system, such as the pressure relief valve.