HVAC Water Treatment

Cooling towers being one of the most commonly found systems to benefit.

The 4 Major problems faced by water based cooling and heating systems

It is important to note that scaling, fouling, corrosion and bio-growth activity are interdependent on each other and cannot be considered in isolation.


Reduced heat transfer efficiency due to scaling causes inefficient or increased energy consumption.


Creates flow restriction and adds stress on pump and chiller by causing bio fouling, solidification fouling and corrosion fouling to the system.


Essentially all metals used in HVAC systems especially the older ones are corroded resulting in water seepage, pipe leaks that leads to mold growth


Conditions such as elevated temperatures and contaminants influences bio-growth of anaerobic and aerobic bacteria that increases rate of fouling and corrosion.

In addition, having Legionella under control is as important and vital to the health of people working and living in the immediate environment.

Press Release Malaysia Health Director General (2013)

A 40 year old female employee died and was tested positive for legionella.

There has been a total of 281 (24.2%) of 1,158 workers who have been screened and found to have experienced respiratory symptoms.

Sources of legionella were found in cooling towers, humidifier, boiler and other indoor fountains.

During further investigation, legionella species isolated from cooling towers in Kuala Lumpur were surveyed for the presence of legionella and organism were grown from 12 out of 46 samples of water collected from 30 towers.

Additional Problems caused by poorly performing systems

System Tripping due to scale and biofilm build up causing down time.
Complaints due to poor thermal comfort.
Impact on energy efficiency where 1 ° F increase in Approach Temperature is approximately 1 % increase in energy consumption.
Increased rate of corrosion causes premature wear of equipment.
Legionella health concerns.

Introducing Clean CT-01™

Clean CT-01™

The Great Little Water Company is proud to introduce The Clean CT-01™ Green HVAC Water Treatment System, a comprehensive solution to address all cooling and heating water issues.  This system is the fruit of GLWC’s continuous research & development work since year 2000.  The system is capable of simultaneously address fouling, scaling, corrosion and bio-growth issues.  This is made possible through the cross application of electronic, mechanical and chemical engineering.

The Clean CT-01™ system can be used to clean, rehabilitate and protect all pipes and wetted surfaces of equipment in air conditioning system, boilers, reheat water system, drinking water and sewage water systems.  Clean CT-01™ has 13 years of proven track record from Canada, USA, Singapore and Malaysia.

Unlike most water treatment solutions, The Clean CT-01™ Green HVAC Water Treatment System not only treats the water but it goes a step further to ensure efficient heat transfer occurs between water and its corresponding elements.  This enables water savings by significantly reducing water wastage during the treatment process.  Further, it ensures health and safety of occupants by controlling microbial and bio-growth which also prevents diseases such as Legionnaires Disease and by avoiding the use of toxic chemicals that can otherwise compromise safety and health.  Finally, the green system also prolongs equipment life by preventing corrosion through protective coatings and ensuring that water is non-corrosive.

Safety and health

The Clean CT-01™ Water Treatment System utilizes non toxic chemicals designed to treat drinking water pipelines, where all ingredients are GRAS (Generally Recognized As Safe) and approved by the Canadian Food Inspection Agency.

All ingredients in Clean CT-01™ products are either food grade, biodegradable or used in food surface preparations. As a result, no toxic chemicals are used on site. Hazards associated with the toxic conventional water treatment chemicals such as handling and storage are thus eliminated. Clean CT-01™ also reduces health risks to building occupants or passersby within the vicinity of the cooling towers and further prevents runoff water pollution which can contaminate food sources via rivers and the sea.

Clean CT-01 is approved for use by registered food establishments by Canadian Food Inspection Agency. This means, no health implications are expected if the product is used on food preparation surfaces: no harmful residue is left behind because the product itself is not harmful. Following please find the letter by the Canadian Food Inspection Agency regarding CT-01:

While our solutions address issues at their root causes, we target to deliver sustainable outcomes that provide long-term benefits to the client.  Some of our products and services include:

Pipe Cleaner

This ready-to-use product accomplishes rehabilitation, commissioning and cleaning of piping systems in general. Removes build-up of fouling, scale and other contaminants from the inside of existing and old systems. Specially designed for Open & Closed air-conditioning loops that are not new.

AHU Tube Cleaner

Ready-to-use product which delivers de-scaling and de-rusting of the inside of AHU and FCU cooling coils. Totally non-toxic system that leaves behind a corrosion-protected system with restored heat transfer efficiency.

Before Clean CT-01™

After Clean CT-01™

Before Clean CT-01™

After Clean CT-01™

Pipe Flusher

This ready-to-use product presents a complete solution to flush newly installed air-con and boiler water loops. Helps get the best out of the air-con system with minimal hassle during commissioning.

Clean CT-01™ and How it Works

The treatment principle

The system was developed to address problems at their roots instead of just the symptoms. It achieves this without the use of any harsh chemicals. Listed below are the major problems, root causes and solutions:

  1. Scale Problem:  caused by calcium and magnesium ions which are dissolved in the incoming water supply.  Solutions:  (1)Pre-treatment prevents these ions from entering; (2)Commissioning removes previous build-up; (3)Live time routine treatment keeps system at steady state; and (4)Utilization of harvested rain water, if possible, provides almost-demineralized water for free.
  2. Fouling Problem:  caused by 1. suspended solids, 2. bacteria plus nutrients and 3. residue from chemical reactions.  Solutions:  (1)Continuous filtration; (2)continuous disinfection; and (3)non residue creating chemicals.
  3. Corrosion Problem:  caused by acidic or basic water and iron bacteria.  Solutions:  (1)buffering pH at non corrosive level; (2)suppressing iron bacteria; and (3)introducing a self-limiting protective coating which complements the natural oxide layer.
  4. Bio-growth & Safety Problem:  caused by fast bacteria propagation and usage of toxic chemicals.  Solutions:  (1)continuous disinfection; (2)elimination of toxic chemicals; (3)removal of nutrients (food for bacteria); and (4)removal of suspended solids which can be home for bacteria colonies.

What it does

The treatment will precipitate unwanted dissolved minerals through chelation and sequestration processes. It also removes fouling and dirt from wetted pipe & tube surfaces which can otherwise restrict flow and heat transfer. These unwanted contaminants are then physically filtered away.  Filtration is the most cost effective way to reduce hydraulic wear which is classified as physical deterioration of pipe surface caused by sedimentation and particulates present in the water.

Over time, this process creates a stable water quality.  Corrosion is prevented through (1) keeping the pH at 8.0 to 8.5; and (2) leaving behind a self-limiting protective coating to enhance the natural oxide layer of wetted surfaces. Bacteria is controlled via a low-toxic disinfectant.  Bacteria tests are carried out periodically for monitoring purposes.

All of the Clean CT-01™ ingredients together perform the following 4 key actions to prevent scaling, inhibit corrosion and control bio-growth:

  1. Sequestering and chelating: Chelating agent breaks down the corrosion & scale build-up. Brings contaminants into solution, forming free ions. Sequestrant then neutralizes the free ions, clustering into micro-particles, too small to damage pumps.
  2. Adsorption and Micro-abrasion: Calcium precipitates on adsorptive media and is filtered out.  The micro-abrasive adsorptive media gently polishes the wetted surfaces to further prevent scale formation.
  3. Peptising, emulsifying and dispersing: Brings sludge into suspension, which allows filtering of micro-particles and other unwanted material, leaving the system efficient and clean.
  4. Protective oxide coating: Covers all wetted metal surfaces, protecting against corrosion and healing micro-cracks while maintaining optimal thermal conductivity.

See the illustrations below for visualization of the 4 key actions:

What It Can Do: System Rehabilitation

An old cooling tower system was converted to Clean CT-01™ ongoing treatment in May 2009. Prior to treatment, inner pipe surfaces were very corroded, rough and showed a lot of calcium scale. Only 4 months into the treatment, the condenser water piping was opened up. The surface had become much smoother with significantly reduced amount of corrosion. The client has continued to receive our ongoing service since.

Clean CT-01™ is capable of rehabilitating both open loop and closed loop systems.

Resolving it All - Open Loop System and Closed Loop System

Our Complete Engineering Solution for Your Needs

Open Loop System Water Treatment


Magnetic Systems, and Electrostatic Systems for preventing scale formation.

For both systems, results of side by side comparative tests with conventional treatment systems were mixed – success of application depends on the experience
Source: 2007 ASHRAE Handbook pg 48.5

External Pre-Treatments such as reverse osmosis (RO) and ion exchange (IE)
Effective in terms of scale control however fail to address the problem of corrosion, fouling and bio-growth. Recommended as part of a solution only.

Water can be softened using RO or IE to prevent scale build-up instead of using acids to dissolve existing scale. Soft water however is corrosive to galvanized steel
Source: 2007 ASHRAE Handbook pg 48.4

Ozone Generators for water storage.


Hybrid System is an integrated system to address corrosion, scale, microorganism and sludge.

The key components are:
1. Electronic Water Conditioner
2. High Capacity Filtration System
3. Non Toxic Food Grade water Treatment compound.

Pulse Powered Electric Field Device is an ASHRAE endorsed technology in the ASHRAE Green Guide. US Green Building Council’s (USGBC) green building rating tools, LEED also recognizes this technology for their green building certification.


Traditional treatment induces chemicals automatically (metering pumps) or manually to solve the following problems in the described ways:

1. Scale: Acid wash of the system or Threshold Inhibition Chemicals or Scale conditioners
2. Bio-growth: Application of Biocidal Chemicals: Oxidizing or Non-oxidizing biocides
3. Corrosion: Prevention through application of film forming chemicals in combination with controlled blow-downs
4. Deposition: Control through controlled blow-downs


No hazardous waste going down the drainage.
No consumable e.g. chemicals.
Environmental friendly.


Capital Expenditure – payback period estimated @ 2.5 years (SING $ 150,000 +) medium sized system
Not effective if make up water is high in minerals or dissolved solids; e.g. if hardness is >500 ppm or Sulfates >100 ppm which is often the case.
Not suitable for water temperature above 43 °C.
Not suitable for long piping systems due to insufficient ozone time residence.

Concern with corrosion, does not control corrosion effective, water parameter balancing is needed to be done.
Frequent maintenance is mandatory.

Research by ASHRAE shows that ozone is only marginally effective as a scale and corrosion inhibitor. Must be used in combination with other methods.
Source: 2007 ASHRAE Handbook pg 48.5


Combination of non-toxic food grade chemicals and pulse powered electric device reduces chemical use by 60% while maintaining system performance

environmental friendly


Higher capital cost than conventional chemical.
Still uses chemical.



Low Cost: approximately SG$14 – 18/ton/year.
Interchangeable Suppliers.
Industry Standard at the present time.


All methods depend on toxic, hazardous chemicals.
Various elements lead to premature deterioration of HVAC components, shortening the system life-span.
Maintaining appropriate concentrations of chemicals is a complex balancing act.
Traditional chemical treatment often fails to deliver on its promises, resulting in energy inefficiencies as well as health risks due to pathogens propagating in the system.
Necessity of frequent blow-downs results in heavy water consumption, but if blow-down are not practices the systems operate at low energy efficiency.
Blow-down water requires treatment or disposal in accordance with regulations because it contains impurities and chemical residue, incurring extra costs.
Build-up (scale, corrosion and sediment) reduces the effectiveness of chemical biocides.

Closed Loop Doctor Clean CT-01 Water Treatment