combi boiler shakes violently when turned on

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Hi, my Biasi combi boiler (think its non-condensing) has started to shake when the heating is turned on. The higher the thermostat on the boiler is set, when the ch is turned on, the worse the shaking. If the thermostat on the boiler is on the lowest setting when its turned on i can slowly turn the thermostat up without the scary shaking, but it does still shake a bit.
I live in a flat (10 storeys up) and this isnt the original boiler (that had a french sounding name?) the flue is a metal flue that was part of the original system. The flue is quite long, about 18mtrs with 3 bends in it. The biasi was installed in 2007 and worked fine till this year, when it started shaking when the heating is fired up. when the hot water is on it only does it if the bath tap is turned on fully, otherwise not a problem.
Does anyone know why its doing this? :cry:
 
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Firstly, your description of a flue which seems ridiculously long and from an alien manufacturer is scary. Please have it checked professionally asap.
If the (B&Q special) Biasi was fitted in 2007 it should have been a high efficiency (condensing) one. That's been the law since 2004, with very few exceptions.

Your banging boiler (should I ever meet her!), appears to have a broken or seriously underperforming pump. Before replacing it I'd be inclined to check that the heating system water isn't full of sludge.
Sludge can also cause the diverter valve to stick in the CH position, even though the diverter head has switched to HW mode, but you would have noticed this as rads getting warm when you run a bath, for instance.
Do you have to top-up the pressure regularly?

MM
 
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No, the pressure is fine and the system doesnt need topping up. The flue length can be shortened by citing the boiler in a different place, but from your response I'm guessing I need to change the flue to a biasi specific one, or change the entire setup. Can this be done without external access? I'm on the top floor (10 storeys up) and I would need a cherry picker for external access. The only other way is to go through the roof. Would I need building control to ok that, or would permission from the freeholder be enough? Its a listed building but the top floor is a new addition.
 
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Could be that the boiler is scaled or has sludge buildup, as has been said though you really need to get the whole install checked as it sounds horrendous
 
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This spoof poster knows a lot about boilers and I am surprised more of you did not recognise him as an imposter before!

I have no idea who he is but presumably one of the regulars who likes his fun!

Anyone seen Joe-90 lately?
 
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