DIY Doctor

Main navigation

Boiler Pressure Help With Worcester Bosch Boiler Green Star 30si

Postby Ronnierome » Mon Nov 18, 2019 4:32 pm

Wondering if anyone can point me in the right direction.
I have a Worcester Bosch boiler green Star 30si.
It keeps losing pressure, it doesn't seem to be losing it from radiators as I have checked them all for air but all full of water and heating as they should, the pressure dial does go up to about 1 bar when heating is on but drops back down to near zero when off, I top it back to 1.5 bar but a couple of days it's right down again.
Cheers for any help.
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Mon Nov 18, 2019 4:28 pm


Simply Build It

Postby ericmark » Thu Nov 21, 2019 10:08 am

Odd thought I had posted answer, anyway I would look at the expansion vessel, normally inside the boiler there is a tank with water one side and nitrogen the other and as water expands the nitrogen compresses, if either the nitrogen leaks out or the flexible separator fails then when water expands it be be ejected and when it contracts pressure will drop, there is normally a car tyre type valve on nitrogen side, and air will normally work just as well.

The rub is to remove the cover to get at it, often means breaking the gas tight seal, so needs a gas safe guy to do it.

You can get tanks which can fit anywhere on the system, mainly for when a very large system and too much expansion and contraction for built in one to handle, never bought one, so not a clue on cheapest option.
Rank: Project Manager
Posts: 2659
Joined: Fri Oct 02, 2009 8:49 pm
Location: Llanfair Caereinion, Mid Wales.

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics