Why ensuring good water quality adds up

For financial, health and safety reasons, ensuring good quality water within the heating and water system should be a priority as buildings reopen after lockdown, says Andy Green, commercial technical director at Baxi Heating.

Andy Green, technical director, Baxi Heating

As UK commercial buildings are reactivated and installation projects resume, there has been much discussion about the safety aspect surrounding water quality within the commercial heating system.

But ensuring good quality water should not be restricted to newly reopened buildings. Quite simply, heating and hot water systems perform better, more safely and more reliably with good quality water circulating in them. Even completely new heating systems with new boilers, new water heaters and new pipework should be chemically treated before usage.

Why? Without the appropriate treatment and routine monitoring, scale build-up, settled sludge and microbiological contamination in a closed-circuit system can lead to inefficiencies, poor performance and potential equipment failure after even a relatively short period of time.


Scale build-up

Let’s look in more detail at the causes and consequences of poor quality water.

Scale build-up is one of the most common problems. Take boilers for example, where scale deposits on heat transfer surfaces mean that they have to run hotter for longer, reducing their efficiency.

The build-up of scale and debris can also cause noise in the boiler, as well as high temperatures due to little or no flow, which can cause part of the system to fail.

With around 60% of England classed as having hard or very hard water, this places a significant number of commercial heating systems at risk if the water is left untreated.


Corrosion can also have a negative impact on system operation and the longevity of a boiler and/or water heater and their components. Corroded systems that are blocked with sludge and debris will force the equipment to work harder and for longer, as the circulating water is unable to transfer the heat efficiently throughout the system. This drastically reduces energy efficiency, increasing running costs as well as associated greenhouse gas emissions.

For the customer, the result is unnecessary cost and the inconvenience of system downtime. This in turn can affect the productivity of building users and in some cases result in temporary shutdown – a scenario that newly re-opened businesses will want to avoid at all costs.

Microbial contamination

So, while there may be pressure to get through the backlog and complete a job quickly, it is important to ensure that the system is cleaned and flushed effectively just before and after commissioning.

During installation, surfaces can become contaminated or oxidised with dirt and debris. According to BSRIA guidelines, cleaning and flushing these bacteria from the system pre-commissioning, on top of regular system monitoring, is just as important as the design process itself in ensuring good water quality.

Water treatment programme

BSRIA, ICOM and leading heating manufacturers all recommend flushing, chemical cleaning and the use of appropriate inhibitors as part of a water treatment programme. If a new heat generator is being installed on an old system, we recommend a gentle neutral-pH clean four to six weeks prior to the installation, followed by a more aggressive (though still neutral-pH) chemical clean over one to two days, along with power flushing.

Following this, an initial dose, and ongoing use, of a high-quality inhibitor will prevent corrosion and any further build-up of scale, helping to maintain high operational efficiency and extend the life of the system.

The chemicals used must be in line with the manufacturer’s recommendations, which can usually be found in the installation manual. As inhibitors need be applied on an ongoing basis as required, it is important for the person responsible for maintaining the heating system to be able to find and refer to this information — so the installer should point it out at handover.

We suggest that water quality is routinely checked with remedial flushing and cleaning implemented into the maintenance regime. Testing water quality at regular intervals can highlight any issues early on, helping to save money in the long run.

Heating and hot water systems perform better, more safely and more reliably with good quality water circulating in them

Get the balance right

Water treatment specialists can provide guidance on measures to avoid scale build-up and corrosion. Whether testing pH, levels of microbial matter, water hardness or inhibitor levels, engineers can use an onsite test kit or send samples to a laboratory for analysis. Operatives can then determine which substances need to be added to rectify the levels within the system, or whether it needs to be cleaned and flushed completely.

A regular biocide treatment will prevent bacteria from multiplying. If bacteria are left untreated, large deposits of slime can form, creating biofilm which in turn prevents inhibitors from functioning.

Keeping pH water levels neutral will protect the metal components. If an aluminium boiler heat exchanger comes into contact with water with a very high pH level from a nitrate-based inhibitor, for example, pit corrosion can occur on the surface of the heat exchanger. Similarly, very high pH levels within systems containing stainless steel can increase the possibility of stress corrosion cracking the material. In both cases, the pH level of the water can impact on the longevity of the boiler.

Follow best practice

Ensuring good water quality for optimum system performance can bring financial, health and safety benefits to businesses across the UK as they look to minimise energy costs wherever possible post lockdown. Adhering to best practice guidance for water quality within closed-circuit systems will help avoid unnecessary costs from energy wastage, poor system performance and the need for early part or plant replacement, while protecting the safety of the building occupants.

Installers and contractors – as well as designers and maintenance teams – all have their part to play. With good communication across the project team, the most appropriate water treatment programme can be implemented and maintained, and maximum benefits reaped.

For more information, visit: www.baxiheating.com

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