Added X400, do I keep all lockshields open, or rebalance?

[Fordy81]

So we've got a very neglected system that is sludged up, lots of rads cold at bottom. I emptied out the F&E tank, scrubbed it, then flushed through cold water for a while. I've now added Sentinel X400 and refilled the system with all lockshields/trv's open fully.

Do I leave them all open for the 4 or 5 weeks, or should I rebalance the system? Problem is the downstairs rads don't get overly warm unless it is balanced. Don't know whether that's because the pump is on the way out, or upstairs is fed from 15mm pipe and downstairs 8mm, or what?

But if the downstairs rads aren't getting hot, doesn't that mean the X400 won't be flowing through it? And the downstairs rads are worst effected!

 

[oldbuffer]

1. You don't have to shut off both ends of a radiator to stop flow through it, just the TRV's or wheel head valves will do.
2. If the main issue is with the downstairs radiators, I'd shut off the upstairs ones to force flow through downstairs.
3. Once the downstairs have ha a good flush through, gradually reopen the upstairs ones.
4. So, on a daily basis, shut off upstairs via TRV / wheel head, run for a few hours, open upstairs (perhaps more each day) and run for balance of day.
5. At the end of the period, flush out the X400 with all the sludge, refill, add inhibitor, bleed and re-balance.

 

[Fordy81]

Thanks oldbuffer

 

[Fordy81]

So when I refilled the F&E tank on Saturday, the water was obviously clear.

This is it today. Is that a sign the X400 is working or would it always look like that?


Also, when it comes to flushing it out of the system, I've read it's better to have the pump running. How do I do this as normally I turn the boiler off and put the 3 port valve in the manual/locked position?