Too much of a good thing?

[bpowell555]

I put some fernox system preserver in after I drained the system and since then I've swapped out three rads to be sandblasted - out of a total of 8. Should I add another dose, or might that be too much? Or drain the system and refill? Sealed system not a combi, so no header tank.

The last dose was just over a year ago and the rads have been taken off about one a month since october, the last is due back this week.

Cheers!

 

[gas4you]

If it was the old MB-1 then I wouldn't just add more.

If it is the 500ml concentrate then I would.

 

[JohnD]

see what concentration they recommend, then consider what the volume of water is.

I have an old boiler with F&E and 10 biggish rads, i measured mine once, it hold 20 galls (about 100 litres) so with Sentinel I get a 1% solution (recomended) with 1 litre. I should think most modern houses hold less. I added another which gives leeway for any draining e.g. when decorating behind rads. But as I am very mean and have an F&E I can put the drained struff into a bucket and tip it back in through a filter when finished. Luckily I have almost zero sediment.

 

[bpowell555]

The water drained off is crystal clear but the last rad had been shut off for a few months and there was some black stuff at the bottom... I'll check the fernox box and maybe drain and refill later depending what it says... no idea what the system capacity is!!!

Cheers!

 

[bengasman]

I don’t know for sure if ALL inhibitors can be mixed but usually it won’t hurt if the concentration is a bit higher than necessary. Too little is certainly no good.