Worcester Bosch 30si, zero pressure

johntyburger · 5 Jul 2017

was using the shower earlier and the temperature kept changing. Checked the pressure gauge on boiler and it read zero, opened the top up valve and could hear water flowing in, after a minute or so the flow seemed to stop but the pressure is still zero.
I'm getting hot water at an even temperature now.
Central heating has been turned off at the wall thermostat for weeks.
No obvious drips from the overflow outside
Any ideas of what to check before I have to call a heating engineer?
Thanks

terryplumb · 5 Jul 2017

sounds like the pressure gauge might need replacing .try tapping it ,lightly ,with finger nail . see if it moves . if you have zero pressure the boiler will not fire up. as it is ,you must have over 1 bar . so gauge is not giving true reading.( sometimes they can just stick )… as for why the boiler lost pressure that could be a leak ,or maybe just needed a top up . see how it goes over the next few days , if it drops again it will need further investigation .

johntyburger · 5 Jul 2017

Thanks for that reply, bizarrely I went to tap the gauge but it was already showing 1bar This was several hours after I last checked it. I will keep an eye on it

Elkato531 · 6 Jul 2017

The tube to the pressure gauge may be getting blocked up so its slow to show pressure changes. IIRC the 30Si doesn't have a low pressure lockout so it will operate at low pressure until it locks out on overheat as it dry fires. A service should identify problems with the pressure gauge and/or expansion vessel. A flat expansion vessel is very common on these. Keep your eye on the pressure relief outlet and get it serviced.

AGAS · 6 Jul 2017

johntyburger said:
was using the shower earlier and the temperature kept changing. Checked the pressure gauge on boiler and it read zero, opened the top up valve and could hear water flowing in, after a minute or so the flow seemed to stop but the pressure is still zero.

now you may have to change the prv as well

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Worcester Bosch 30si, zero pressure

johntyburger

terryplumb

johntyburger

Elkato531

AGAS

DIYnot Local

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