CH Corrosion inhibitor for large system

[Vortex5]

I am about to take delivery of a 475 litre thermal store/heatbank, and once installed at home the resulting system will have a total primary volume of about 650 litres!

Have been considering the subject of corrosion inhibiter.

Fernox MB1 is widely available for 20 quid for 4 litres "sufficient for a typical 100 litre system".

sell a product called CURA at £3.20 to treat 100 litres. There is another called PROTEX (I thought they made condoms) for £4.03 SENTINEL X100 is £13.21.

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I've used FERNOX for 25 years but do not fancy paying £100+ to inhibit my system.

Question:

Are the cheaper inhibitors such as those sold by BES any cop? Are they good value, or a false economy?

david

[Martin Pentreath]

Subsidiary and related question: does anyone know what these inhibitors are chemically? I've sometimes wondered whether I can buy the active chemical itself direct from somewhere, not account of having a 650 litre system, but on account of being tightfisted.

[Fredxx]

I'm sure a little googling would get you an answer, I got this

presume it's ok to use ethylene glycol in primary circuits of pottable systems.

[Dave Liquorice]

Ethylene glycol is antifreeze, used in thermal solar systems to prevent freezing. This isn't the same chemical used to inhibit corrosion. That was mentioned in a recent thread in here, some phosphate IIRC (doubtful...).

[Andrew Gabriel]

Ethylene glycol is anti-freeze, not inhibitor.

Don't normally need to use anti-freeze in primary circuits of domestic heating systems, but even when required (e.g. for circuits with outdoor pipe runs), ethylene glycol is not permitted because it's toxic, and might leak into the potable water if a heat exchanger leaks.

[Stuart Noble]

The COSSH H&S pdfs on the Screwfix site list ingredients

Diammonium dimolydbate might not be that easy to source!

[Andrew Gabriel]

The X100 I recently drained out after 7 years in a sealed system was still clear, although it had a strange smell. (Wouldn't normally last that long, but system is very well sealed, requiring almost no topping up.)

[peter richards]

Go for soft water at the start of your cold water system this will mean that the problem= s are removed at the start rather than lower down the stream cost =C2=A3120 for say 50y= ears and cheaper washing [less powder]

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