spluttering from vent pipe when pump start/stops

[puzzlebobble]

thanks for your advice JohnD.

There are some black bits in the water but not that much. I still think the main problem might be a partially blocked feed pipe and I'm not sure the x400 will be enough to shift it.

When the X400 has been in for four weeks I'm going to drain the system, insert a new bit of pipe and fit a magnaclean. Hopefully that'll finally sort the problem.

Any other suggestions would be gratefully received.

 

[puzzlebobble]

Does anyone else have any other suggestions of causes for the symptoms described and how I should test for them? I'm planning on draining down the system this weekend and would prefer to get all the potential problems sorted with just one drain down.

Thanks in advance for any other suggestions!