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Elliott Oxton
Elliott Oxton, Plumber
Category: Plumbing
Satisfied Customers: 65
Experience:  Lead engineer at eoxtongasservice
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How do I reduce the pressure, the pressure was zero I

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how do I reduce the pressure, the pressure was zero I connected the hose opened the valves until the pressure reached 1.5 shut the valves and the pressure went too 3.0. The boiler is a greenstar junior 24i

Good day, My name is ***** ***** i have been working as a heating engineer for over 18 years. I am sorry you are experiencing this issue with your boiler. It can be disconcerting when you see the pressure rise so high. But the boiler does incorporate devices that will eliminate risk and damage to you or your property if the boiler was installed properly.

Now regarding the problem at hand. If you have topped up the heating pressure and it has continued to increase in pressure this would indicate that the valve that you used to top up the water pressure has stuck open. Is there a second valve (i believe it is a small grey handle on this model) that you can try and turn off? Does this help the issue?

Is there any more to the issue that you can share with us to help us identify the exact problem? Did the pressure continue to increase after the boiler pressure was topped up? Or does it only increase when the boiler is used (heats up the water)?

Does water discharge from the boiler to the outside as it is used?

I hope that together we can quickly find the answer to your problem so that you know exactly what you need to have done to fix it.

Looking forward to hearing from you soon.

Warm regards,


Customer: replied 10 months ago.
Both valves are fully closed, the pressure reduces when the boiler is working and when idle is now reading 2 bars. I can not get at the over flow, it's sealed and goes direct into a waste pipe.
my concern is that this situation could damage the boiler.
Regards John

Hi John,

I totally understand your concern. Boilers are designed to run between 1 - 1.5 bar but can also run when the pressure is 0.8-2.3 bar. Most boilers have a protecting that releases the water when the pressure reaches or goes above 3 or 4 bar depending on the boiler. So your boiler has protections in place to save it from damage which i hope brings a little comfort until the main issue is resolved.

If the pressure problem is due to it being over pressurised you could try draining a little water out of a radiator bleed valve. Let out a little water until the pressure is at about 1.5 bar. Have you tried this yet? If you have done this but it has continued to cause pressure issues then please let me know so that we can talk through other options to resolve the problem.

When you have a chance i would be grateful if you could rate my responses and support for you with this problem. It would be great if you could click on the 5 star rating above. This is the only way that i receive compensation for the time i spend answering questions and it will help me to better support you in the future.

You can continue to ask me questions regarding this issue. I look forward to hearing from you soon.

Many thanks,


Elliott Oxton and other Plumbing Specialists are ready to help you
Customer: replied 10 months ago.
Hi' Elliott,
This morning the pressure is back to 1.5, seems it has sorted it's self out. Thanks for tip of opening the rad. valve.
Thanks for your assistance.
John Morton

Good day John,

Im so happy to hear that it has been resolved. Thank you for looking to Justanswer for help. I hope that in the future I can give you assistance again if you have any other issues.

Have a good day.