Thanks for all your help and advice.

A couple of questions to put this to bed please!

Why is the water brown?

seems a sure sign of corrosion in your system

you could drain the system and refill it with appropriate amounts of inhibitor

And if the brown water problem can't be fixed. Can the overflow be extended down the wall by using a pipe to take away the dirty water from the wall?


Finally, what type of pipe (material) and fittings could be used? If it's ever been done before?

get a engineer in to sort the problem rather than bodging it to avoid the problem for a couple of days, either the PRV(pressure release valve) is passing or you exspantion vessle is empty meaning the pressure in teh system has nowhere to expand to so it is released out of you PRV more than likely its both

Thank you.