x100 - why exactly 1 or 2 litres.

[Albumen]

Just done some work on my CH. Drained down (though not completely). Added x400. Let it go through each rad on it's own (all the others closed). One by one. Will leave it for another couple of weeks, drain, mains water flush.

When I fill back up, why can't I add 1.5 litre of X100? Does an opened bottle of Sentinel go off?

Sentinel say 1 litre for 8-10 rads. I've got 11 (well, 13, but I count the 3 tiny ones that go round the curved bay window as one), including towel rail. So don't I need just a bit more than one litre?

I know it's not a million pounds to buy the stuff, but I know that in about 6 months I've got to drain it all again, for a load of work on the kitchen. I'd rather use one and half bottles now, and one and half bottles later.

Most of the rads are actually quite small (downstairs loo, kitchen, box room etc.). The pipework is mainly 15mm, a bit of 22mm. No 28mm. Presumably the Sentinel recommendation is just based on the amount of water in the system. 1920s semi, so not long pipe runs. Sealed system, combi boiler.

 

[Dan Robinson]

Yes it does go off, but it takes a while depending on the environment.

Just bang two bottles in and stop being a cheapskate.

 

[hazetimesfive]

http://www.plumbcenter.co.uk/en/heating/water-treatment/fernox-ch3-protector-25-ltr-36705

 

[JohnD]

I measured mine once during a drain, it was less than 100 litres total even with F&E and a big iron boiler. They say 1% mixture. As you have a combi I bet yours is less than 100.,

 

[Dan Robinson]

Bet mines more than 100 - next refill is gonna be with a glycol mix