Maybe - he did add some rads after I'd been there, and I told him about if he drains down etc... You thinking it's globbed inhibitor in f+e?
Hello Ted808,
It was probably because the F&E Tank did NOT have any Corrosion Inhibitor poured in after filling the Heating system that the `Bacterial slime` built up on top of the water.
When Inhibitor is put into an Open Vented Heating system a small amount is supposed to be poured into the F&E Tank after the system is full up to prevent the build up of Bacteria / `Slime` in the Tank.
That used to be printed on Fernox and Sentinel Corrosion Inhibitor containers - I have not needed to read any of them for about the last 40 Years.
However - as we know a newly filled Heating system will need venting for at least another couple of days and dependant on the size of the system and how much Air has to be released / water filled from the F&E Tank during that period that small amount of Inhibitor can be diluted enough to make it ineffective / not able to prevent Bacterial / `Slime` build up.
So ideally the small amount of Inhibitor should be added to the F&E Tank after ALL of the Air has been vented from the system which will probably not be by the Heating Engineer / Installer so not practical.
There will be some evaporation of water from the F&E Tank which over a period of time will also cause the dilution of the Inhibitor in the Tank and cause it to not be able to prevent Bacterial build up.
In my opinion Heating systems with F&E Tanks should have Corrosion Inhibitor added to the Tank at least every 5 years -
better still - have the system drained, refilled and chemically cleaned and then drained and refilled with new Corrosion Inhibitor about every 5 years.
Having a Heating system that was filled and Corrosion Inhibitor added 10 - 15 or 20 years ago and expecting the Inhibitor to still be protecting the system after all that time is a `false expectation`.
Something else regarding the dosage of systems that is often misunderstood / not fully explained by the Corrosion Inhibitor manufacturers is the
`treats up to 10 Radiators` / 100 Litres system capacity specification
- they mean 10 x SINGLE PANEL Radiators.
So if we do not want to actually calculate the water capacity of each system I would always recommend 2 x Containers of Corrosion Inhibitor for the `average` House or Flat with 10 or 12 Radiators.
What You have encountered regarding your description of `being able to pick it up ` ! is quite extreme in my experience - although not unheard of.
Regards,
Chris
