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Boiler running at 3 bar, is that normal?

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bmc
Aspiring Pro
Posts: 376
Thanks: 69
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Registered: 28-02-2017

Re: Boiler running at 3 bar, is that normal?

You could always try the old adage....

 

When all else fails read the .... manual!!!

 

Brian

Community Veteran
Posts: 4,668
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Registered: 16-10-2014

Re: Boiler running at 3 bar, is that normal?

@nozzer, there was no air in any radiators, not even the towel rails that are the highest point in the system! But with that said on checking the pressure's dropped to 2.5bar.

Community Veteran
Posts: 4,668
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Registered: 16-10-2014

Re: Boiler running at 3 bar, is that normal?

@bmc Are you actually serious! Wink

Jonpe
Seasoned Pro
Posts: 1,206
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Registered: 05-09-2016

Re: Boiler running at 3 bar, is that normal?

The instructions for my Vaillant combi boiler says that it should run at one bar, and be topped up when the pressure drops below 0.8.  The service engineer usually tops it up to about 1.4 when he's finished, and there is a red line on the gauge at 3 bars.

RichardB
Aspiring Pro
Posts: 293
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Registered: 19-11-2008

Re: Boiler running at 3 bar, is that normal?

The Worcester bosch advice on sealed system pressure is https://www.worcester-bosch.co.uk/support/troubleshooting/faqs/home-heating-faqs/how-often-should-i-...

 

Last year my boiler system pressure was exceeding 2.5 bar when hot and 1 bar when cold.

I had recently had the boiler serviced and had assumed the service included a check of the pressure vessel...

The pressure vessel is inside the back of the boiler. To replace it would require total removal of the boiler!

 

Taking matters into my own hands:

1) I isolated the feed and return valves on the boiler

2) drained the boiler using its drain valve (not the pressure releif valve)

3) The pressure vessel has a car tyre schrader valve on the air side, I put my foot pump on the valve and inflated the pressure vessel to 0.8 bar. This forced out 4 litres of water from the boiler. Through the open drain valve.

4) close drain valve and open the feed and return valves.

 

Boiler pressure is now 1 bar cold and 1.5 bar when hot :-)

 

Over time the air had slowly leaked from the pressure vessel reducing the air volume.

 

More info on sealed systems can be found at:

http://wiki.diyfaq.org.uk/index.php/Sealed_system_FAQ#I_suspect_the_expansion_vessel_is_faulty.2C_ho...