Closed circuit treatment
                     Closed Loop & Closed Circuit 
Heating & Cooling
Water Treatment Services is a leading 
independent UK water treatment company 
offering a full range of expert services for 
the management of closed systems, closed 
loop heating, cooling and closed circuit 
chilled water systems.
Our closed loop water treatment solutions 
address the problems of corrosion, fouling, 
biofouling and scaling that affect the reliability 
and performance of closed circuit and closed loop 
water systems.
Our specialist services for closed circuit water 
systems are delivered by in-field experts who 
combine the latest high performance closed loop 
water treatment techniques to help reduce costs, 
save energy, enhance operational efficiency and 
reliability, and extend asset lifecycles.
Expert closed system & closed loop water treatment 
solutions
Our specialist closed loop and closed circuit water 
treatment solutions include:
CLOSED LOOP WATER TREATMENT & SERVICING
In-field closed circuit and closed loop water treatment, 
engineering support and maintenance services to control 
corrosion, fouling, microbial fouling and scaling.
MONITORING & VALIDATION
Latest water analysis equipment to monitor and validate 
closed circuit water treatment programme performance.
ENERGY EFFICIENCY
Expert investigation and analysis to identify process 
improvement and energy efficiencies involving heating, 
cooling and chilled water systems, and heat transfer 
processes… energy efficiency →
Full national UK coverage
With offices in London serving the South and South East 
England, Manchester (North West), Birmingham 
(Midlands), Bristol (South East England and Wales), 
Leeds (North and North East) and Glasgow (Scotland), 
supported by regional teams of specially trained engineers, in-
field water treatment specialists and technical experts Water 
Treatment Services can offer professional, cost effective 
solutions for the treatment of closed circuit heating, cooling 
and closed loop chilled water systems throughout the UK and 
Ireland.
Contact us today to learn how our expert water treatment and 
closed circuit engineering support solutions can help you to 
save energy, reduce downtime, optimise costs and operational 
efficiencies, and increase asset reliability. To speak with one of 
our water treatment experts call us on 0330 223 31 31 or 
simply use the button below to get our full contact details or 
submit our contact form.
Contact Us Today
What are closed system water circuits?
Closed systems, closed circuits or closed loop water systems 
are used in many commercial, industrial and process 
environments where they provide heating or cooling to work 
spaces, other internal environments, and manufacturing and 
industrial processes.
Closed circuits operate as a “closed loop” or “closed system” 
meaning that they are effectively sealed and the water inside 
the system is not exposed to the atmosphere. This means that 
a closed loop system contains a fixed volume of water that 
recirculates and tends to suffer only negligible water losses.
Problems affecting closed loop systems
If closed loop systems or the water used within them are poorly maintained 
or left untreated it can lead to problems that will affect energy usage, cost, 
asset performance and reliability. Specifically, these problems include 
corrosion, fouling, biofouling and scaling to a lesser extent unless there is 
significant water loss requiring additional make-up water.
CORROSION
FOULING
BIOFOULIN
G
SCALING
To combat such problems closed loop systems and the water used within 
them require suitable treatment.
Successful closed circuit water treatment
The successful management of closed loop systems requires a holistic approach to the 
maintenance and protection of both the system, its components and the water used in 
them against the detrimental effects of corrosion, fouling, biofouling and scaling.
A well-managed waster system has significant benefits and will help save energy, 
reduce downtime, optimise costs and operational efficiencies, and increase asset 
reliability.
Water Treatment Services holistic approach to the successful management of 
closed loop water systems involves control of the following issues:
CORROSION CONTROL
Appropriate control measures to minimise system corrosion.
CONTROL OF FOULING
Controlling system fouling to reduce blockages, maintain energy transfer efficiencies, 
and flow rates.
CONTROLLING BIOFOULING
Controlling biofouling from microbial slimes, pseudomonas bacteria, nitrifying and 
sulphate reducing bacteria.
SCALE CONTROL
Scaling in closed circuits is generally less of an issue but can be problematic where 
significant make-up volumes are required.
Inhibiting corrosion in closed loop water systems
Corrosion can affect closed loop heating, cooling and chilled water systems 
even though oxygen levels tend to be lower in such fixed volume water 
systems. However, it is more common in heating systems where higher, 
fluctuating temperatures can increase rates of corrosion.
Corrosion control is important as if left unchecked it can lead to the 
degradation of metallic components and increased fouling from corrosion by-
products. This can lower flow rates, cause blockages, and reduce reliability 
and life-expectancy. It can also lower heat transfer efficiencies which 
increases energy costs.
A thorough understanding of system metallurgy is essential in the 
development of an effective corrosion control programme. Several different 
metals are commonly used in closed loop systems and care needs to be 
taken that any chemical water treatment products selected are compatible. 
This is especially true for systems that contain aluminium.
Chemical corrosion control can be achieved by incorporating specialist closed 
loop water treatment technologies including high performance corrosion 
inhibitors and oxygen scavengers in to the water treatment programme.
Controlling fouling & microbial slimes in closed circuits
Closed circuit water systems can become fouled from sources 
including suspended solids, corrosion by-products, scaling and the 
build-up of microbial slimes from pseudomonas bacteria, nitrifying 
and sulphate reducing bacteria.
The accumulation of such fouling in the form of sludge and 
suspended solids can cause blockages, reduce heat transfer 
efficiencies, and constrict flow rates. It can also cause localised 
corrosion and bioaccumulation.
Pseudomonas bacteria can cause significant microbial fouling 
issues in closed cooling and chilled water systems. As 
Pseudomonas bacteria proliferates throughout such closed circuit 
systems thick microbial slimes can build-up to contaminate the 
water, reduce cooling efficiencies and increase operating costs.
Successful treatment of closed loop water systems that operate 
below temperatures of around 80oC should incorporate a broad 
spectrum biocide to control the growth and build-up of bacteria 
and microbial slimes within the closed system.
Controlling scale formation
The formation of scale (sometimes called limescale) in closed circuits 
and closed loop systems tends to be less of an issue because of the 
fixed volumes of water involved. However, if there are regular water 
losses that require significant make-up volumes then treatment for 
scale formation may be required.
This is usually more of an issue with heating systems, especially 
those using hard water, as the increased system temperatures make 
the hardness salts more insoluble. The build-up of scale on internal 
surfaces can cause blockages, reduce heat transfer efficiencies, and 
constrict flow rates.
Closed systems water treatment training
The industrial and process water treatment specialists at Water 
Treatment Services have developed an extensive series of 
professional water and wastewater treatment training courses that 
includes WTS 0060 “Water Treatment for Closed System Heating & 
Cooling Water Circuits”. This specialist training for closed systems 
comprises an intensive one day course designed for facilities 
managers, water treatment service engineers,  maintenance and 
engineering contractors, plant operators, and those with 
responsibility for the installation, pre-commissioning, maintenance 
and on-going management of commercial and industrial closed water 
systems used in heating, chilled and cooling water installations… 
water treatment training →
Expert closed loop water treatment solutions
Contact Water Treatment Services today to discuss your 
closed loop water treatment requirements. We can provide 
expert advice and engineering support regarding the 
management and water treatment of closed loop heating, 
cooling and closed circuit chilled water systems to help reduce 
costs, save energy, enhance operational efficiency and 
reliability, and extend asset lifecycles.
With offices in London serving the South and South East 
England, Manchester (North West), Birmingham 
(Midlands), Bristol (South East England and Wales), 
Leeds (North and North East) and Glasgow (Scotland), 
supported by regional teams of specially trained engineers, in-
field water management specialists and technical experts we 
can offer professional, cost effective water treatment and 
engineering services across the whole of the UK and Ireland.
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