How much central heating protector to add?

[semolina]

I'm about to refill my (open vented) central heating system and have bought Fernox MB-1 (4 litre bottle) to add to the system. Instructions on the bottle indicate this is enough for an average (100 litre) system of up to 10 single panel radiators.

When draining the system I estimated the volume to be about 50 litres (with 8 radiators of varying size, some double panel). Should I add the entire 4 litre bottle when refilling the system or will this be too much MB-1 for my system? Should I add only half of the bottle? Can the MB-1 cause damage if I add too much?

 

[Hot&Cold]

Be brave,shove it all in

 

[semolina]

Be brave,shove it all in

What, and then keep my fingers crossed???

 

[oilboffin]

Stick it in it will not hurt a thing.Bob

 

[Jackrae]

Many years ago I contacted Fernox re concentration as I was in the habit of annually adding a couple of litres to compensate for any evaporation losses that might have occurred via my open-vented header tank. Their response was that I could increase concentration as far I liked, even to 100% (if I wanted to spend money). There would be no increased benefit but equally no compromise either. In the intervening years I have change my system to a closed pressurised system, replaced boilers twice (an other of life's stories) and the fluid is still clear having been in service for 30 years.