Radiators don’t heat up evenly, and am missing an Expansion Vessel. Do I need it?

What happens if the expansion vessel is too small?

An undersized vessel can cause big pressure swings too but those swings would have been present since installation. If, however, you’ve recently extended your central heating system by several radiators, the existing expansion vessel could be too small and this would also cause larger swings in pressure.

What happens if my expansion vessel fails?

If water comes out of the valve it means that the diaphragm has failed inside the expansion vessel, and you will need to replace the vessel or with some units you can just replace the internal neoprene bladder. If air comes out of the Schrader valve you need to check the pressure of the charge in the vessel.

Why are my radiators not heating up properly?

Check for Trapped Air and Bleed Your Radiators



If just one (or a few) of your radiators aren’t heating up, the most common reason for this is trapped air. If you’ve just turned the heating back on after the summer, air can become trapped in your radiators, causing them to be warm at the bottom but cold at the top.

Why is only half my radiator heating up?

When a radiator appears to be cold at the top but still warm at the bottom, the usual culprit is air trapped in the heating system. There is a very simple approach to fixing this, which is to bleed the radiator. Bleeding a radiator releases the trapped air, allowing your radiator to run more efficiently.

Do I need an extra expansion vessel?

As we all know, when water is heated it expands and wants to take up more volume. As the system is basically a closed loop, consisting of the boiler, pipework and radiators, it is necessary to provide some space for the water to expand into. This is why the expansion vessel is required.

What does an expansion vessel do on a heating system?

Expansion vessels, also known as expansion tanks, can be found in most domestic pressurised heating systems. If you have a combi boiler, you will have an expansion vessel. This vessel contains air and water from the central heating system, and its purpose is to maintain the right level of pressure in the system.

How do I know if my expansion vessel is broken?

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Quote from Youtube video: So I've got the manual for the boiler. And with a bit of help from the guys in before them I found out how I need to check to the expansion vessel is still working so when we find a shorter valve we'

How do I know if my expansion tank is working?

Finally, testing your Thermal Expansion Tank is important and should be tested once a year when you flush your water heater. If your Thermal Expansion Tank is hanging from a pipe, you would push the Schrader Valve (air valve), located on the bottom of the tank, if the air is released then the tank is working properly.

Why does the temperature on my boiler keep dropping?

The most common reasons for a boiler to lose pressure are: Releasing air or water from a radiator when bleeding it. A leak from the appliance or on the system most commonly from radiator valves or system components.

How do you fix a half warm radiator?

Quote from the video:
Quote from Youtube video: If the bottom of your radiator is heating up but not the top half it's most likely that air is trapped in the system. It's simple enough to sort this out yourself by bleeding the radiators.

Why are some of my radiators hotter than others?

Some radiators occationally get quite a bit warmer than others. When this happens it usually means that your central heating system is out of balance. In some instances, radiators can be different temperatures due to the distance that water that heats them has to travel from the boiler or pump.

Why are some of my radiators cold?

If a radiator is cold or has cold patches as a result of trapped air, the excess air in the system needs to be ‘bled’ out. To do this, simply use the bleed key provided by your radiator manufacturer to undo the bleed valve. This valve is usually on the top corner (or thereabouts) of a radiator.

Do I need expansion vessel for combi boiler?

Despite the fact that you may not have heard of an expansion vessel before, it’s a crucial part of your heating system that allows it to maintain a constant pressure. If you have a closed-water heating system in your home, such as a combi boiler, you will have an expansion vessel.

How many expansion vessels do I need?

A chilled system would require minimal expansion due to the lower temperatures.

Do I need an expansion vessel with a system boiler?

Unlike regular boilers, system boilers do not require an expansion tank or external expansion vessels. This makes them both easier to install and less in need of space.

What happens if expansion tank is full?

An expansion tank is used to prevent issues related to excess pressure from your home’s hot water supply. Without it, you would be at risk for damage to your water lines, fittings, and water heater.

What is the purpose of an expansion tank on a boiler?

Expansion tanks help to provide a cushion for water to expand to when it is heated. If this cushion of air is not available, the pressure in the boiler system can become higher than the system can handle. This results in the pressure relief valve opening, which then discharges water.

What happens when boiler pressure is too high?

If the boiler pressure is too high, there’s an increased chance of leaks developing in the system. But if boiler pressure is too low, the system won’t work as well. So keeping the correct boiler pressure is important to make sure that your system heats your home efficiently.

Do you bleed the radiators when the heating is on or off?

Should I be bleeding radiators hot or cold? Always make sure your central heating system (your boiler) is turned off and your radiators are cold before attempting to bleed them. When turned on, your radiators contain hot water, and you could be at risk of scalding yourself if you bleed them at this time.

Is 2.5 bar too high for a boiler?

Your boiler should be running between the 1 bar and the 1.5 bar, which will be in the green section of the boiler pressure gauge. If the bar is hitting over 2.5 bars, then the pressure from the water in the system is too high, and anything below 1 bar is too low.