Blocked H overflowing vent pipe

[marlin123]

My heating system is a fairly conventional pumped system, gas-fired boiler, pump, two 2-way valves, HW cylinder, radiators, F&E tank in loft.

The system is 17 years old and has serious sludge build up (17 yrs worth) which has blocked the H causing the vent pipe to overflow into the expansion tank. British Gas wanted to sting me for £773 for a powerflush and Magnaclean installation.

So far I've treated the water with Sentinel X400 left for 4 weeks, then drained down system removed all the radiators and use a pressure washer to blast all the sludge out of the radiators and a lot of sludge it was. The system runs a lot better now but the H is still partially blocked as magnet proves.

What is the best course of action to clear this iron deposit in the H? What will an air separator do to help?

Many thanks for any suggestions

 

[hi-spec plumbing heating]

What is the best course of action to clear this iron deposit in the H? What will an air separator do to help?

Many thanks for any suggestions

cut it out and fit new section.
air seperators block just as much.

 

[Softus]

If the 'H' pipework is accessible then I'd just replace it all.

Edit: one minute too late; bah.

 

[gas_man_gaz]

the air sep is meant to stop air being drawn into the system.. if ya boiler has a overheat stat fitted ya could combine the cold feed and the open vent