Radiator pipe flushing

[DIYspanner]

I want to flush the feed and return pipes on what I believe is the by pass radiator in my CH system.

The radiator is a 900x600 Myson double panel with both lock shield valves fully open. The radiator does get hot but the bottom middle gets luke warm if that even after hours having the CH on.

All other radiators are single panel 300, 400 and 500 with TRVs fitted. None of the lock shields are open more than ½ turn and all get hot.

I’ve had the radiator off and tried flushing it through, both upright and upside down while tapping the bottom with a soft faced mallet yet very little sludge has come out. Basically, using all the how to stuff I’ve seen on YT.

With the radiator removed, do I simply open each lock shield and let the water pour out into a bowl?

By the way, all ground floor radiators, including the 900x600 Myson, have 10mm pipes where as all 1st radiators have 15mm pipes.

The boiler is a Vaillant Turbomax Vuw which is in good condition.

 

[oldbuffer]

Try re-installing the radiator and running the system. With it running, turn down the lock-shield valve on the problem radiator and see if the bottom centre starts to heat up. If it does, then with both valves fully open, water was going straight through too fast without losing heat to the whole radiator.

 

[martygturner]

Before you put the rad back on open both valves turn about and let a few litres of water out, air locks can sit a way back in the pipe work.

 

[DIYspanner]

What I did was, with the lock shields closed, drain the radiator off through its drain spout on the neck, then opened the lock shields one at a time and let the water from the pipe drain out through the drain valve.

No sludge evident in the collected water.

When filling the radiator, I opened each lock shield separately for 20 seconds to bleed any air out of the pipe into the radiator.

I've opened each lock shield 1/2 turn so will see how it performs with the CH on.