How To Reduce Pressure On A Combi Boiler
A well-functioning combi boiler is essential for maintaining the comfort of your home. If you notice that the pressure gauge on your boiler is reading too high, it’s important to lower the pressure to prevent things like leaks and damage to your heating system.
In this guide, we’ll run through the necessary steps on how to reduce the pressure in your combi boiler, so that it operates efficiently
What Causes High Boiler Pressure?
Boiler pressure is indicated by a pressure gauge, which you can usually find either on the front of the boiler or directly beneath it. The optimal pressure of a boiler is anywhere between 1 and 1.5 bar. As long as the gauge sits within the working range, as indicated by a green line, then your boiler is working as it should.
When boiler pressure increases this isn't always a sign that something's wrong. For example, if you've just put your heating on and the pressure ticks upwards, as long it stays within that green safe zone, this is perfectly normal. You can expect small fluctuations within the pressure range depending on whether the boiler is on of off.
It's when the boiler pressure moves up, into the red zone that you'll need to determine what's causing it. The most common cause of high boiler pressure is over-filling your cental heating system and this tends to happen after repressurising the system. Another possible cause is not closing a valve properly on the filling loop, or if you notice any leaks from the valve, the filling loop could be faulty and need replacement.
Essential Tools To Reduce Pressure On A Combi Boiler
Method 1: Check the Filling Loop
Begin by inspecting the filling loop, you'll find this located underneath the boiler. Double check that both valves are closed; if either remain open, they can cause the pressure to continue rising. If you notice any leaks coming the valves, it could be time to replace the filling loop.
Method 2: Drain Water from the System
If the boiler pressure remains high after checking the filling loop, you can move on to draining water from the filter.
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Locate the filter beneath the boiler and place a small bowl, or similar, to catch the water.
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Carefully turn the radiator valve until water is released.
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Keep an eye on the pressure gauge as you do this; it should begin to drop.
If the pressure gauge fails to move as water is released from the system, the gauge itself could have malfunctioned. In which case, a new one may be in order.
Method 3: Bleed a Radiator
If you prefer, you can drain water from your heating system by bleeding a radiator. Keep in mind, this method can take a little longer.
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Insert the key into the bleed valve at the top of the radiator.
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Turn it counterclockwise to release air and water.
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Be careful as water will spurt out, so be sure to place a suitable container beneath the bleed valve.
Once complete, check your pressure gauge to see if it's moved back into that green safe zone.
Restart the Boiler
Once you've reduced the boiler pressure to its optimal setting, turn the heating back on. Watch the pressure gauge as the system heats up; it should rise slightly but remain below 2 bars. If it exceeds this, further investigation may be necessary.
Consider Expansion Vessel Issues
If, after trying out the above mentioned methods, your boiler pressure remains high this could indicate a problem with the expansion vessel which is housed inside the boiler. In such cases, we'd recommend seeking advice from a qualified professional.
