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worcester bosch combi-boiler problem

Postby rhylbloke » Wed Sep 16, 2009 4:50 pm

We had a new worcester bosch greenstar combi-boiler and new radiators with thermostatic valves installed one year ago. Now that we have started to switch the heating back on after the summer, I find that I'm having to bleed the radiators every day. The towel warmer in the bathroom only gets hot at the bottom, and you can unscrew the bleed screw on the top of it completely without water coming out. The temperature control on the boiler is set to maximum and the pressure dial is reading zero. Is it a lack of pressure/ not enough water in the system, or both ? I can see the adjustable valves at the bottom of the boiler, but don't want to fiddle with any of them without knowing what I'm doing, and the manual doesn't mention how to remedy lack of pressure or not enough water. I'd be grateful for any advice.
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Postby lennykemp » Thu Sep 17, 2009 8:09 pm

I am not a plumber but my daughter had the same problem ,There was a small leak in her system, and over the summer months the system lost all pressure. You need to re charge your system with water using the fill loop up to the recommended pressure for your system { check your manual )You also need to re bleed the whole system Check for a small leak it looks like you have one
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Postby sparx » Sun Sep 20, 2009 1:18 pm

Hi, I believe your boiler does not use a filling loop, it is inbuilt.
Inside the bottom removeable plastic cover should be clipped a tee shaped plug with some 'O' rings on which is inserted into a hole in the pipes between cold mains in and rad circuit, turning tee piece untill it locks in place,( like fitting a light bulb)
then using the valve next to it and watching the pressure guage slowly open valve to pressurise system to around 1 bar. it will take some time to start to raise pressure if water lost as it will refill first THEN when it starts to move guage it will rise rapidly, be carefull not to overpressurise, you will need to bleed some rads which will drop pressure & repeat process untill air out & system at 1bar.
with valve turned off, twist and pull tee piece out,there will be a little water lost so have a bowl under it!
If no tee then you will need to talk to local plumber/heting Eng. nicely to try to borrow one, as some take the tee piece away to prevent people messing with boiler,
regards Sparx
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