Worcester-Bosch Greenstar 24i Junior shows 0 bar when off

[greg.harvey]

Hi all,

I have a Worcester-Bosch, about 3 months old. Something has been nagging me about it for a while, but I never got around to asking. When it is on and running, the system pressure needle is always bang on the 1 bar line, which is perfect. However, as the boiler cools after operation, it slowly reduces until it reads 0 bar when stone cold. Is this right? I find it slightly odd, as my old boiler (an early Ideal Sprint combi) stayed at 1 bar whether it was running or not.

I don't want to over-fill the system, but I don't know if it should read 0 bar when off or whether it should actually read 1 bar when off and rise to 2-3 bar when running?

Cheers,

G

 

[GasMan1965]

It should be 1 bar when cold and rise maybe half a bar when hot !!

 

[GasMan1965]

If it rises more than half a bar when hot then you have an expansion vessel problem,,, maybe the expansion vessel hose wasnt attached!!

 

[greg.harvey]

Yikes!!

I'll put some more water in it right now then and see what happens. What would the effect be if the expansion vessel hose wasn't attached? It's strange, because we have no evidence of any leaks but clearly it's lost pressure somewhere...

 

[GasMan1965]

If its not connected or the vessel has gone then the pressure will rise to 3 bar where it will discharge out of the pressure relief pipe outside!!

 

[gas4you]

Could simply be that when new you bled the rads of air and didn't top up the pressure after doing it.

The boiler also has an auto air vent in it, so air can be bled out without you knowing.

I have systems go to zero after about 3 days due to the AAV letting out air.

 

[greg.harvey]

Ok - thanks guys. I'll keep an eye on it for a few days and see how I get on.

 

[greg.harvey]

Just a quick status update - boiler has held steady at 1 bar when off and about 1.5 bar when running, just as GasMan1965 described.

Seem gas4you's thought about the AAV is likely the cause. Perhaps the system was still full of air that bled itself out via the boiler over a week or two. I'm amazed the fitter didn't mention it! It's pretty fundamental information - keep an eye on the pressure for a few weeks in case it drops off because of the AAV!


Anyway, seems fine now. Thanks again!

 

[GasMan1965]

Well done buddy !!

 

[sweetrobinson]

I also have pressure problems! I have a Greenstar Worcester Bosch boiler, but the people who installed it 30 months ago didn't really have the time to let us understand how it works. The pressure is now between 3 and 4 (is it dangerous?) and yesterday night there was no hot water. I heard that the fee for a visit from the Bosch technician is 185 pounds - which I cannot really afford at the moment. Can anyone help? We have a small child with arthritis....

Many thanks!