draining CH after Fernox Restorer - how clear is clear?

In article , dave @ stejonda writes

Not answering your question directly, but can you flush it through rather than filling and draining? Hose connected to a drain point near the boiler & fill continuously via the filling point or header tank. Close radiators off in selected areas to force flow through distant rads.

My system was designed to make this possible, with an isolation valve in the boiler feed, but you may be able to stop reverse flow through the boiler (except when you want to flush that loop) by closing the pump isolation valves (if fitted).

I flushed through for 30mins, closing off selected rads/areas to make sure everything was flushed, water was totally clear at finish. No need to bleed when flushing if you don't drain first.

In message , fred writes

{I cancelled my original article as soon as I'd sent it, because the water suddenly got clear, which is why most people won't have seen it}

This is an excellent idea ISTM and something I'll consider organising for the next time I need to do this in ~3 years time. :)

Bliss!

erm, why would you be doing this again in 3 years time? Surely when you finally refill this time you'll be adding a corrosion inhibiter. Shouldn't need touching again unless you have problems with the system.

cue .andy ...

Tee hee.

Not much to add really.

Inhibitors do degrade over time, although I'm not 100% certain what the mechanism is. When I had an open vented system, I would test at least annually and after about three years the inhibitor was showing marginally with the test kit. so 3 years isn't a bad rule of thumb.

I would then drain a little water and top up, but then on every alternate occasion (i.e. every 6 years) would drain, flush and refill with fresh inhibitor.

Now with a sealed system it's just coming up to two years and no sign of degradation. It could be that the degradation mechanism is with it being open to the atmosphere and some amount of oxygen dissolving but I am not certain.

.andy

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