In the HVAC industry, water and energy use are closely related. In fact, we could say that they are interdependent.
A poorly maintained cooling tower with basin leaks or overflow and a high concentration of dissolved solids can have its efficiency reduced by 10 to 35%; a 0.25 inch of scale in a heat exchanger can increase consumption up to 40%, and even a small amount of biofilm in a chiller works as an insulator, impeding heat transfer and requiring around 40% more fuel.
In all cases, energy is wasted and utility bills go up.
There are many ways of saving energy when we talk about water treatment.
Controlling and optimizing cycles of concentration to reduce blowdown and make-up water, installing drift eliminators to avoid drift loss, and utilizing a side-stream filtration system are all effective solutions for a cooling tower.
Improving pump efficiency to adjust flow conditions, and implementing a complete air handler coil maintenance program to protect the chilled water system and to maintain conditioned air setpoint temperatures also have a positive impact on energy consumption.
Even harvesting HVAC air handler condensate can save you tons of energy. However, none of these actions replace having an appropriate water management plan.
In HVAC systems, water treatment is crucial.
Water can be easily responsible for 5% of utility costs, and even though the number may not sound threatening, a good water treatment program has a direct impact on operational costs, resource renovation and gas emissions.
That is because treated water prevents unwanted changes in water temperature, flow, and volume, preventing your system from biological growth such as algae, buildup slime, biofilm, air bubbles that cause oxidation, etc.
According to the Association of Water Technologies, the general objectives of water treatment are the following:
- To keep heat transfer equipment as clean as possible, in order to maximize water flow and heat transfer efficiency.
- To protect the heat transfer equipment and associated piping from corrosion and fouling damage.
- To conserve water and heat, and to meet or surpass all applicable air and water quality regulations.
- To accomplish all of this in the most technically appropriate, safe and cost-effective way possible, in the best interests of the customer.
There are numerous different ways of treating water, but we can divide them into two categories: chemical and non-chemical.
Chemical Water Treatment
The chemical water treatment is still the most adopted solution in the market. Yet, it is more costly and less environmental friendly, obviously. Chemicals commonly used are chlorine, bromine, isothiazolinone, phosphonate, and molybdate.
Even though most of them dissipate quickly, molybdate is a heavy metal and due to a cooling tower overflow could accidentally be drained into the storm system as opposed to the sanitary sewer system. In this case, the metal would end up contaminating rivers!
Non-Chemical Water Treatment
Non-chemical water treatments are not only an eco-friendly solution that can qualify a company for LEED points, helping achieve the LEED certification. Non-chemical is cheaper (no costs with chemicals handling, storage, and disposal), efficient, and require significantly less hours with maintenance and operation because they operate at higher cycles of concentration. In doing so, less blowdown wastewater is generated, and as a consequence less makeup water is required.
Non-chemical water treatment does not change water chemistry, yet prevents scale and corrosion problems, and inhibits bacterial growth in cooling tower systems, ensuring energy efficiency.
There several non-chemical water treatment systems available in the market, but one of them stands out because the solution does not even touch the water, conducting an electromagnetic field into the piping network.
This electromagnetic field allows minerals in the water to stick to each other rather than to pipes and equipment (traditional scale). Because the electromagnetic signal is conducted into the pipes and can be seen throughout the system, instead of at a single location, the entire system is treated.
The electromagnetic signal lowers the bacteria count in the system by using electroporation, flocculation, and encapsulation, reducing biofilm growth by 98% and corrosion, therefore promoting equipment operating life. Another big advantage of this safe and chemical-free treatment is there are no costly piping modifications or system downtime because of the installation bolts onto the pipe.
One last benefit of this particular non-chemical treatment is measurement because it allows measurable energy savings from reduced pump horsepower and improved chiller efficiency, as well as measurable operational and maintenance savings from reduced system teardown.