2 Radiators working out of 8 Radiators

probably like this a few years ago I had exactly the same problem, only the 4th plumber sucked the blockage out of the system and everything worked as it should

Hi, Following on from your question, there could be a couple of issues here. Like you stated a blocked pipe or even a faulty valve, if you have had a chemical flush you could possibly have a air lock or the system needs balancing. Many Thanks Steff @SRM

I’m rather inclined to think the original pipe work is under sized coursing sludge build up are the pipe work 22mm right up the reg rails to the last radiator? Have the lock shield valve been altered? If the pipes are undersized you can balance the system through the lock shield till dirt builds up in the half opened valves

Hi, If you have a power flush and it was successful even for only one day. This tells me your pipework is blocking. After the flush has been carried out the blockage reappears. Which means there must be lots of sludge in your system. It sounds like you need more than a normal flush of your system. I would be trying to find the blockage (normally lower pipework) and drive the debris through at high pressure until it completely clears. Some pipework may need replacing and might be quicker. But first.... please check all valves are open!!! Regards Paul