Greenstar 30i Boiling loosing pressure (wierd)

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flibberflops

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Worcester-Bosch Greenstar 30i

This is probably easily understandable to someone but has got me completely stumped!

The Pressure gauge is dropping about 0.1 bar everytime the radiator burner/pump kicks in. If I put the heating on it goes down from 1 bar to zero in about 2-3 hours. (constantly dropping 0.1 bar everytime the burner kicks in until reaches zero).

If I pressurise the system to 2 bar and leave overnight without use, it is still two bar in the morning (so I am pretty confident its not the rads/pipes)

I have also noticed that when the hot water is turned on, the pressure will drop 0.25 bar while the hot water is running before returning back to previous presure reading when the hot water is turned off.

I have also noticed that the hot water still works even though the presure gauge is reading zero (I thought there was supposed to be a complete system cutoff when the presure drops too low?)

Cannot find a leak anywhere... including around the boiler area or external pressure relief pipe. I cannot easily monitor the condensation pipe due to the way that it has been plumbed in.

Any idea whats going on?

Any pointers much appriciated.
 
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Pin hole leak somewhere?
Cylinder/he-ex?

Is the HW clean and clear?

If you keep repressurising, the water is going somewhere.
 
flibberflops said:
If I put the heating on it goes down from 1 bar to zero in about 2-3 hours. (constantly dropping 0.1 bar everytime the burner kicks in until reaches zero).
Click to expand...
Have you seen the pressure rise at all whilst heating is on?
 
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CBW said:
Have you seen the pressure rise at all whilst heating is on?
Click to expand...

Funny you should say that, before today I would have said no but during today I noticed that heating went from a standing 1.9 Bar (overnight pressure test) to 3.5 bar 20 mins after the heating went on... obviously the PRV was dripping at that point.

I don't know if that is total coinsidence but our mains water has a PRV at the stop cock set at 3.5 bar? However, left the heating running and it went down to 0 Bar as normal after running for a while.
 
flibberflops said:
Thanks I will check out the expansion vessel next
Click to expand...
That is not what CBW asked
If you need help, you need to respond
CBW said:
Have you seen the pressure rise at all whilst heating is on?
Click to expand...

There are guys here that do this kind of work day in day out. They do not get paid to make posts to assist end users with boiler issues. They do this as a matter of goodwill not personal gain.

Good you have responded. Above was written before you responded
 
Tbf @DP, I think the reply was for Johnny, as there was a link to an expansion vessel thread.
 
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Reactions: DP
flibberflops said:
Funny you should say that, before today I would have said no but during today I noticed that heating went from a standing 1.9 Bar (overnight pressure test) to 3.5 bar 20 mins after the heating went on... obviously the PRV was dripping at that point.

I don't know if that is total coinsidence but our mains water has a PRV at the stop cock set at 3.5 bar? However, left the heating running and it went down to 0 Bar as normal after running for a while.
Click to expand...
It does sound expansion related, be it the vessel or a blockage in the communication pipe.
 
flibberflops said:
Funny you should say that, before today I would have said no but during today I noticed that heating went from a standing 1.9 Bar (overnight pressure test) to 3.5 bar 20 mins after the heating went on... obviously the PRV was dripping at that point.

I don't know if that is total coinsidence but our mains water has a PRV at the stop cock set at 3.5 bar? However, left the heating running and it went down to 0 Bar as normal after running for a while.
Click to expand...
That's exactly what happened to my son's boiler.
See my thread, there are detailed instructions on how to inflate vessel to the correct pressure (if your valve is visible, otherwise call someone)
 
Update... Finally just tried the schrader valve and it is indeed Niagra falls, which i guess it need to get someone in to get the expansion vessel replaced.

Question... Can I ask a 2nd part to this question to see if I also have a 2nd issue (or confirm the issue is related)??

Before this issue with the pressure started, I had an issue with the hot water. Very intermittently (everry 4 days ish) the hot water would run cold when in the shower. If you waited about a minute it would go hot again. Then a minute later it would go cold again. Then a minute later it would go hot again... and stay hot from that point on. Pressure was 1 bar on the boiler and although it was hard to catch the problem (due to the random nature of the issue and being in the shower) the only time it was breifly witnessed on the boiler itself no error lights was showing. It was impossible to duplicate, oftern having to wait days for it happen again.

Then when this other pressure drop issue started, the issue with the hot water went away completely until today. Two weeks had passed without the hot water issue happening (never went 4 days before). Today, out of the blue I had the worst event of hot water running cold that I ever had... it took 5 minutes of the water running hot and cold (cycled about 4 times) until it eventually stabled out to constant hot. (pressure again was 1 bar)

Therefore... would the expansion vessel issue also cause intermittant problems with the hot water too... or do I have some other issue as well???
 
terryplumb said:
You have more than one issue. You should engage an engineer to check it all out and repair.
Click to expand...
Thanks... I did have an engineer in for the intemittant hot water issue before the pressure issue started. The bolier checked out ok and with no way to duplicate the issue there was nothing to fix. They were really good about it and didn't charge me but not sure how I fault chase this one... any ideas?
 
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