DIY Doctor UK DIY Forums

Hi,

I added some Sentinel X400 cleaner to my central heating system and I’m due to flush the system soon. (Sentinel Tech Support recommended leaving the X400 for 2-3weeks before flushing)

My boiler is a glowworm micron 60ff (it’s not a combi) and I have a sealed system with an expansion vessel.

I have Gas & Central Heating Cover and I recently had a Gas Safe engineer pop round to fix a TRV problem. Whilst he was here he suggested that when I flush the system I should fully open the isolation/stop valve feeding the expansion vessel, and have the boiler running with the pump set on max speed (ie 45W). Once the water coming out of the hosepipe connected to the drain valve is clear, I should then switch the boiler off followed by the isolation valve, and drain and refill the system as normal.

My question is… is this safe to do?... I have drained and refilled the central heating system a few times in the past but never with the boiler running and the mains feed open.

Please let me know if this was sound advice or not.

Many thanks in advance

Think I have my answer...posted this question on another forum and it seems I was given bad advice by the engineer who visited... ie definitely not a good idea to flush system with the boiler and pump running, even if the cold isolation valve is open to allow mains pressure water into the CHS.