Cooling Tower Water Control System

Client achieves optimum water treatment monitoring compliance along with a reduction in on-going costs.


Cooling systems are key to many cooling processes, one of which is office environment comfort cooling. Operating these cooling systems in a safe and efficient manner and in line with the current HSG274 guidance is essential, to minimise running costs and maintain production whilst ensuring the water quality is controlled.

A requirement of cooling tower water treatment is to manage the ever-changing water conditions and to stabilise the water chemistry, whilst always maintaining satisfactory microbiological conditions. It is common practice for cooling tower controllers to divert bleed water to drain and introduce pre-treated softened water to maintain the TDS levels and cycles of concentration, to introduce primary and secondary biocide products along with combined corrosion/scale inhibition products – all of which have an obvious cost to the operator in terms of water usage and environmental costs.

Sayvol work closely in partnership with our clients to understand their environmental drivers and efficiency targets. One way to assist as part of our added value service is to help to optimise the efficiency of such cooling and dosing systems, whilst minimising waste and negative financial and environmental impact.

Where practicable, such a bespoke installation saves cooling system operators money by reducing the ongoing cost of operation (OPEX).


  • Reduce primary biocide usage.
  • Reduce corrosion/scale inhibitor usage.
  • Reduce water usage / costs through reduced need to regularly drain-down and refill the Cooling Towers.
  • Reduce salt consumption (pre-treatment) / costs through reduced need to regularly drain-down and refill the Cooling Towers.
  • Reduce down-time / increase efficiency for the General Cooling System.
  • Reduce internal labour / micro-management of systems – staff to be better utilised for other important tasks.
  • Reduce callout costs for equipment failures.
  • Increase compliance with ACOP L8/HSG274 guidelines (primary control method for microbiological control including Legionella).


The automated Cooling Tower Dosing equipment and associated filtration unit has been commissioned and is offering the client cost savings for the points noted above.  Our client has peace of mind that they are optimising their compliance with ACOP L8/HSG274. The above reliability also means that the water treatment process requires less micro- management and therefore our client’s site engineers have more time availability for other important day to day tasks.

Reducing OPEX costs


Optimum Compliance


Peace of Mind

System description

Our client manages a prestigious Multi-Tenanted Canary Wharf based commercial office building, the client has six Cooling Towers providing comfort-cooling as well as offering cooling to utility areas such as kitchens and server rooms.

Due to the age of the original automated dosing and filtration equipment, frequent software/probes and general plant failures, the site team were unable to accurately control the Water Treatment, namely excessive chemical (Bromine) usage due to unresponsive and tired probes.  This resulted in frequent drain-downs of the Cooling Towers to reduce excessive Bromine levels, leading to excessive water loss, excessive costs for additional pre-treated soft water supply, excessive use/cost of proportionally dosed inhibitor chemical due to the additional make-up water introduced following drain-downs, not to mention the labour required to micro-manage the individual systems and associated down-times on the Cooling Systems  Ultimately site was not adhering to the ACOP L8/HSG274 guidelines due to the fluctuating loss of primary control method.   

There was also an increased cost with frequent call-outs for failed/failing equipment/pumps/filtration parts.

Previous ageing dosing and control equipment.


As the existing dosing arrangement included a sand filtration system to maintain system cleanliness, Sayvol were asked to offer two options to our client to replace the aging sand filtration with a more modern equivalent sand filtration system and also a comparison equivalent side-stream filtration option. 

Following consultation with Sayvol, our client decided to proceed with an updated sand filtration unit to accompany the new touchscreen Walchem automated dosing array.  The advantages being:


    New upgraded dosing equipment, supplied with full O&M manual and on-site training which is supplied free of charge as part of our commitment to providing a quality service.

    Sand filtration:

    • In this case, sand filtration offered more ‘polished’ water when compared to the side-stream type filtration (side-stream would not remove any discolouring or tainting, which sand filtration effectively removes.)
    • Constant LCD read out of conductivity and flow rate with adjustable threshold relays.
    • The water conductivity level controls are linked in and synchronised with the backwashes of the sand filter as best as possible. This means that blowdown water is not simply dumped to drain but is used to clean the sand.
    • Enhanced operation compared to the older unit, less drain line restrictions offering greater backwash cleaning efficiency.
    • There is PLC control which is fully programmable. 4-20 mA data signals (flow / conductivity) with BMS / SCADA connectivity.
    • Increased reliability due to the age of the previous equipment.

     New automated Cooling Tower dosing system:

    • Large touch-screen display with icon based programming; this makes setup easy and is user friendly.
    • Universal sensor input provides extraordinary flexibility; the same controller can be used with almost any type of sensor needed:
      • Six control outputs allow the controller to be used with more applications.
      • On-screen graphing of sensor values and control output status.
      • Complete flexibility in the function of each relay.
      • On/Off Setpoint.
      • Time Proportional Control.
      • Pulse Proportional Control.
      • In-Range or Out-of-Range activation.
      • Timer-based activation.
      • Activation based upon the state of a contact closure.
      • Timed activation triggered by a water contactor or paddlewheel flow meter’s accumulated total flow.
      • Activate with another output/Activate as a percent of another output’s on-time.
      • Biocide timer.
      • Datalogging
      • Ethernet option for remote access via the Internet or LAN.


    • Our client is achieving a well-polished water quality, along with operating the system within acceptable chemistry parameters.
    • Site are no longer emptying cooling tower ponds and incurring excessive pre-treatment water costs or excessive chemical usages.
    • The new equipment arrangement, recommended, installed and commissioned by Sayvol is meeting the project objectives set out and agreed.
    • Another happy customer! 

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