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My warning light 'fault on pump or low pressure' was flashing on my BAXi Combi 105E system. The pressure reading had dropped to 0.4. Having just had it installed 3 years earlier we thought it was not a faulty pump but a leak in the system. Having removed floorboards we could see water spraying out from where the copper pipe went into the towel rail. On removing the pipe we could see that massive corrosion had taken place in the copper and blown holes in it. The offending part was replaced but just 3 weeks later the same thing occurred.Big holes in the piping. Deciding we could manage without the towel rail the engineer capped off the pipe .

All was well till 1 week ago when the pressure on the system fell to zero.
Fearing the same thing had occurred somewhere else in the system we agin lifted floorboards to find water spraying again from corroded copper piping. It appears we have major contamination but we are at a loss to know why this is happening. The corroded parts (big holes in them) appear to be where the piping has been clipped up with plastic clips and nails to the wooden joists. We have now replaced the offending copper pipe with a section of plastic but it appears that the contamination is now, as expected, attacking other parts of the copper pipe work. It is quite astonishing to see the condition of the corroded pipe. We fear now we will have to totally replace all the copper piping. Has anybody heard of this before and could anybody please advise what course of action we should take. Many thanks.

I take it when the Baxi was installed, they didn't renew the whole heating sytem ?

This is quite a common problem where new pressurised sytems are connected to old radiators, valves and pipework.

The only way of rectifying the problem is to renew the pipework, flush and add inhibitor, to prevent the same thing happening to new pipes.

Try to avoid over-pressurising the system. I know it will discharge to outside at 3.5 bar. but try to keep the pressure between 0.5 and 1.0 bar. until you have replaced the pipework.