Sentinel X400 - drain out or flush out?

[Jabajaw]

@PigletJohn

We have a conventional boiler with a F&E tank in the loft and a hot water tank in the airing cupboard. We have recently moved into a new house and we suspect that the heating system hasn't been serviced or cleaned for a long time. I see lots of brown sludge in the F&E tank and black water from the radiators when bleeding and the rads are at best just luke warm.

I have followed Piglet John advice from a post back in 2014 of using Sentinel X400 and letting the system run for three weeks but I am unsure on the correct way to flush the X400 out. Are there any experts here who can suggest the correct way for my heating system?

Do I just open the drain valve to remove the disperesed sludge and then refill + drain again or do I flush by keeping the grundfos pump and boiler running until the water runs clean? If I just drain without keeping the pump and boiler running will it remove all the dispersed sludge?

I am worried that powerflush may cause leaks so don't want to go down that route.

Many thanks in advance.

I heard you the first time.

Pasted

PigletJohn
Turn off the boiler and pump, turn off or tie up the float to the filling valve , bale out the F&E tank into a bucket, sponge out the remaining sludge, pour the bucket down the WC. Open the drain valve. Open all the bleed valves starting at the highest. Open all the lockshields, noting how many turns for each. When empty, close the bleed valves and drain cock and refill. Run the pump, with the boiler off, and drain again. Repeat until the drainings are clean (there will always be an orange tinge from todays rust). You can then run it as normal over night and drain again tomorrow. This should get most of it out. Check for leaks. On final fill, add X100 and X200.

15:27
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PigletJohn
Save up for a Magnaclean which will be a worthwhile addition.