Corrosion Inhibitor is used in the water in Hot Water ("Hydronic") Central Heating systems to protect ferrous components of the system (including steel radiators and cast-iron boiler heat exchangers) from corrosion caused by the action of oxygen dissolved in the water.
Corrosion inhibitors vary in price from about £5 to £15 (for a quantity intended to protect an average domestic installation). The chemistry of corrosion and corrosion-inhibition is, presumably, well known, so one would expect the various different makes of inhibitor to be pretty much equally effective. Unfortunately simple experiment suggests otherwise.
Corrosion Inhibitor test
- Four bottles were filled each with a similar quantity of water and similar number of (already slightly rusty) nails.
- Inhibitor was added to each of the bottles in the concentrations recommended by their manufacturers.
- The inhibitors used were:
- Fernox MB-1
- Sentinel X100
- Purimachos Protex
- none (control)
- The bottles were then placed together in a warm place (the back of an airing cupboard)
- Six months later the bottles were examined