Thanks. That's enough to nudge me off the fence :-) Operationally the system is good and I've run cleaner through a few times in 15 years & always dosed with fernox. Power flush will come with the inevitable new boiler (Potterton...
I'd just continue the drain / flush / refill / test pH / dose with inhibitor as though everything was normal. I might give it an extra flush for luck.
You will never get a reliable 'theoretical' answer to the question you are asking...
Hello, I put x400 in our system at the end of November, intending to leave it for a few days but took ill and it's still in there. Now on the mend I want to drain it soon & I've just emailed Sentinel who replied:
"The maximum...
Clear pictures of where open vent and cold feed connected to system would be useful.
Get a decent magnet and see if it 'sticks' to pipework in that area
Try pulling some sentinel X400 in system to clear sludge.
Have quite a bit of experience of PDHW on systems;
Firstly you can make any traditional system PDHW without any changing of valves with a NC DP contactor quite easily. Basically on a HW demand the DP contactor opens the circuit and...