Written by Neil Marsh MCIPHE RP RHP EngTech
We have had the opportunity to ask a few questions to Adey’s Mo Jassal, who is their Chemical Technical Manager, in regards to issues raised in one of our articles “Aluminium Heat Exchangers: Built to Fail?“…
MC1 is a chemical water treatment product, typically known as an inhibitor, which is used in central heating systems to help protect against the breaking down of metals within a water-based central heating system.
There are several central heating inhibitor products on the market from different companies, Adey’s MC1 being one of those. There is little information available to both the public and installers in regards to how they work or what chemicals are contained within each and how they help protect aspects of a central heating system. As a result, we have to put trust in the manufacturers that these products will do what they claim.
Any experienced installer can tell you that the effectiveness of inhibitors varies greatly, and each will have their preferred brand, but very few, if any, can tell you why the inhibitor product they use is the best one for your central heating system.
As mentioned in our article linked above, aluminium is a reactive metal that readily reacts in both acidic and alkaline environments, which is now commonly used in boilers primary/main heat exchangers. When questioned, this is what Mo had to say to us about aluminium:
“Aluminium is a reactive metal, far more reactive than copper or iron. However, it is protected by a very stable oxide layer that naturally protects the metal. Corrosion issues occur once this oxide layer is breached and then aluminium metal starts to corrode quite quickly. Aluminium oxide is what we call amphoteric which means it will dissolve in both acidic and alkaline conditions, therefore to maintain the correct pH in heating system water is crucial. If the pH is less than 6.5 or over 8.5 the thin oxide layer will dissolve exposing the metal to corrode. High chloride levels, such as those found in fluxes, also cause pitting corrosion in aluminium which leads to pin holing.”
He then also went on to give more information about the oxide layer:
“The oxide layer does not protect the heat exchanger form acid erosion. In fact, the oxide layer is dissolved in acidic conditions exposing the metal, which reacts and corrodes. This is why you see constant corrosion on the gas side of the heat exchanger. The pH is controllable on the water side by using a well-buffered inhibitor like Adey MC1+. Some alternative treatments do not have the same buffering capacity to protect the aluminium.
Different grades of aluminium alloy will certainly have an effect as some are more resistant than others. However, all will corrode in acidic conditions. Therefore, it is critical to have good-quality water treatment.”
Mo gave us some more information on how MC1 helps to protect aluminium heat exchangers:
“Adey’s MC1+ Protector is a universal multi-metal corrosion inhibitor and contains specific ingredients to inhibit corrosion of aluminium. It utilises both anodic and cathodic inhibition mechanisms for protecting the metal surface. Furthermore, Adey MC1+ contains ingredients which buffer the pH of the system water ensuring that vulnerable metals, like aluminium, are protected from acidic or alkaline conditions.”
What Mo has said confirms our stance on the importance of correctly flushing out a central heating system when installing a new boiler, or when dealing with related problems with an existing boiler. It is essential to remove flux residues from soldering and ensure chemicals that could affect the pH of the central heating system water are removed post installation, especially if your boiler has an aluminium heat exchanger.
How to flush a central heating system and what chemicals to use will depend on the situation. Typically stronger chemicals should be used in conjunction with a power flush machine when fitting a new boiler to an existing heating system, or tackling contamination issues within a current central heating system, such as central heating sludge and limescale. “Cleaner” chemicals are best used for manual flushing methods when installing an entirely new central heating system to remove such things as flux residues.
Adey also has a product called the MagnaCleanse that can be used with a power flush machine to speed up the removal of sludge from the heating system and increase its effectiveness while reducing the amount of water used during the process. It can also be used without a power flushing machine in conjunction with the heating systems pump. This is not a product we have used as of yet, so are unable to comment on its effectiveness for either method. More information can be found by visiting Adey’s website.
For more information about power flushing, click here.
So as you can see, it is essential to use the right chemicals, at the correct doses, to treat your central heating system to get the best levels of protection possible against corrosion. MC1 is a competitively priced product that may have advantages over other inhibitor products on the market, especially for boilers with aluminium heat exchangers. How well it compares to other products is hard to say as a long-term independent study would need to be conducted, which we are not aware of any existing ones, but it is clear to us that Mo knows what he is talking about and MC1, in our experience, is a reputable and popular product.