Case Study – Iron Issues in Closed System Resolved

Reducing Iron levels in closed system from >200pmm to <15pmm within 6 weeks – saving the customer over €100,000 in the process.


Our client was experiencing an issue with high iron levels in their chilled system, following recommendations from our engineers, in January 2023 they decided to go ahead with remedial works to improve the iron levels and increase the efficiency and lifespan of their equipment.

In January 2023 the iron levels were 350ppm and the water in the system was red in colour (NOTE Iron level should be 15ppm).

The first point of action to rectify this issue was with use of chemicals as only a big filtration system was in place. This was successful in reducing the iron levels. In May 2023 we used a chemical cleaner on the system which loosened up some iron lodged in the system, this caused a small spike in its’ levels as expected but swiftly started to reduce again.

In August we began to see the iron levels increase again due to the soluble iron left in the system and an alternative approach was recommended. We installed The Hierro filter as a result, this was installed in September 2023 and results were visible almost immediately. After only 6 short weeks the iron levels in the chilled system returned to below the ideal of 15ppm.

Additionally, a Hierro filter was installed in the heating system which resulted in the iron levels decreasing from 15ppm to 1ppm.

Not only has The Hierro Filter improved our clients water quality and system efficiency, it has saved them over €100,000 and over 200,000L of water as the alternative course of action was to drain and flush the entire system.


8 Story Office Block, Dublin City


While we had been carrying out bi – annual sampling for our client, we had previously advised them that the water in their closed system was deteriorating, with  iron levels in their chilled system reading over 350ppm.

In January 2023 our client approved all recommendations and immediate action was taken to reduce the Iron levels in the system – ideally these levels should be 15ppm.

Chemicals were introduced to decrease the iron levels and proved to make significant improvement, in May 2023 a chemical cleaner caused iron levels to increase rapidly, this was expected as the cleaner loosened a lot of iron from the system. The iron levels began to fall again until August when the tests showed the soluble (dissolved iron) had increased – to 137ppm.

We advised our client that a different course of action should be taken  and after considering a number of options on how to proceed our clients and ourselves agreed  that installing the HIERRO FILTER would be the best and the most advantageous way to go forward.

On the 13th September 2023 the filters were installed, two were installed for the chilled system and one for the heating system. The improvement on Iron levels could be seen immediately.

As of 16th October 2023, the iron levels were still decreasing and the Iron levels in the heating system have decreased from 15ppm – 1ppm.

Our client is exceptionally happy with this outcome as they have already noticed a difference in the running of the chilled system. By installing The Hierro Filter the equipment is running more efficiently and using less energy = saving costs.

The alternative to carrying out this installation was to flush out the entire system which would have cost a lot of time, water and over €100,000. Our solution is 1/5 of this cost and will be a much longer lasting solution.

Our client now has a full water treatment plan in place with monthly visits.


  • Recommended chemical treatment be introduced to the chilled system following recorded high levels of iron (Jan 2023)
  • Weekly testing carried out
  • Chemical cleaner used to free up lodged iron
  • Consultation with client about alternative solution when iron levels started to increase again (Aug 2023)
  • Hierro Filter Installation was recommended and approved (Sept 2023)
    • Iron levels started to reduce dramatically
    • Full water treatment maintenance contract set up with monthly visits


The iron levels in the chilled system decreased from 350ppm in Jan 2023 – 189ppm in August 2023, then from 189pmm to 15ppm in S6 October 2023 because of two Hierro filters being installed. Our clients heating system experienced improvements from the installation of the Hierro filter with the iron levels going from 15ppm to 1ppm in the first three weeks.

The installation of the filter has also saved our client from dumping 200,000 liters of water, and over €100,000 – what they would need to spend if they flushed and drained the water in the chilled and heating systems.

Not only was the installation of the Hierro filter extremely cost effective, but it was also more environmentally friendly and a sustainable long-term solution to the high iron levels in their water systems.


  • The office was fully occupied while the tests were ongoing and therefore had to ensure minimal disruption to the office workers.
  • The filters had to be delivered and installed into both the chilled and heating systems which took manual labour and time.
  • The client was a bit apprehensive about installing the Hierro filter as they were not familiar with its benefits up until this point.


By introducing the Hierro filter in both the chilled and heating system, we have managed to save this business thousands of euro. The filter also allowed the business to avoided flushing both systems, saving over 200,000 liters of water.

The fast, visible results have satisfied our client, and they continue to be impressed with how useful the filter has been. High iron levels in chilled and heating systems can have adverse effects on the system including, reduced efficiency, corrosion, and decreased water quality.

The Hierro filter has provided our client with a cost effective, long-term solution to resolve the high iron levels in their chilled and heating systems.