Chemical water treatment ensures any heating system is fully protected and working to optimum efficiency. Dr Neil Watson explains why this is critical to system longevity and performance.
Contractors responsible for heating systems within environments such as care homes, offices or schools should be aware of the role chemical water treatment must play in the installation and maintenance of any heating system that works on the basis of circulating water from those operated by traditional gas boilers, through to renewable technologies such as solar thermal systems, ground source and air source heat pumps.

Without the correct water treatment, systems are susceptible to sludge, limescale build-up and bacterial contamination, all of which force a system to work harder to circulate water around radiators or underfloor pipes. This means it takes longer for a room to heat up, wasting unnecessary energy, costing more to heat and generating needless carbon emissions.

To combat this, traditional systems need to be pre-commissioned by first cleaning out any debris and then dosing with a reliable inhibitor. Tests have proven that without this - a system can lose over six per cent efficiency in just three weeks. Water treatment can also rectify specific problems. If contractors are faced with a system suffering from cold spots, boiler noise and banging pipes, it is likely that these are symptoms of a heavily sludged system. Powerflushing is therefore the best course of action.

Like traditional systems, renewable heating installations require protection with chemical water treatment as they are also susceptible to frost damage, corrosion, sludge and micro biological fouling.

Solar thermal heating, for example, is really no different from a traditional heating system in terms of water circulating at high temperatures around a system that contains metal. When water and metal come into contact there is a risk of eventual corrosion that can reduce the efficiency. Chemical water treatment will protect those metals critical to solar collectors and solar thermal systems from the affects of corrosion.

However, solar thermal systems differ in that they are subjected to more extreme changes in temperature. This makes it vital to dose with an inhibited heat transfer fluid that can withstand high temperatures in both liquid and gaseous phases and includes frost protection.

Ground and air source heat pumps are also proving popular for smaller commercial installations. In both cases, correct pre-commissioning is key to avoiding future problems that could be difficult and costly to rectify. For new build installations, ground arrays for ground source heat pumps are often filled with water and left while the building is constructed. Stagnant water left untreated makes a perfect breeding ground for bacteria and microbiological growth, which can create an insulating bio film. If the system is then set to run without being cleaned or treated and bacteria contaminates the heat transfer fluid, this can lead to failure of the ground source heat pump in as little as three months.

When commissioning air source heat pumps, greater care needs to be taken to protect the secondary internal system because air source heat pumps are often installed alongside underfloor heating systems, which run at lower operating temperatures - making them even more vulnerable to bacterial contamination.

Contractors should therefore opt for a heat transfer fluid that combines a corrosion inhibitor, anti-freeze and biocide.

• Dr Neil Watson is global technical director at Fernox