Are you trying to understand the costs associated with treating water in your closed loop heating or cooling system?
Want to learn about factors that affect total closed loop operating costs?
In this article, we discuss key variables which affect total operating costs and the impact on water treatment chemical costs.
When you’re done reading this article, you’ll be ready to assess how you can improve the effectiveness of your closed loop treatment program. You’ll also be armed with knowledge to align with a supplier who has your total operating costs in mind.
How the Unique Design of Your Closed Loop Impacts Water Treatment Costs
Several factors associated with your closed loop system impact overall operating and water treatment costs.
Total System Volume and Piping Complexity of Your Closed Loop System
Closed loop treatment products are designed to work at a target application rate in the water. The larger the treatment volume, the larger the initial water treatment chemical cost. For instance, first-time water treatment costs may be 10 times higher for a 10,000 L loop than a 1,000 L loop.
In larger buildings, most systems have primary loops, secondary loops, and zones designed by the mechanical engineering contractor to heat and cool the building on thermostatic control. As weather changes, so do the demands on these systems. Variable degree days of heating and cooling and occupancy levels affect when there is flow through zones and the flow rate through piping. These complexities must be considered when initially charging or topping up a loop to target treatment dosages.
It is important to include all system water in commissioning a new system and in maintaining an existing system.
Is Your Closed Loop System Leaking?
As the name implies, closed loop systems are meant to be closed. However, in most buildings it’s not uncommon for there to be leaks.
Aside from the closed loop system volume, the single biggest factor affecting the ongoing cost of water treatment is whether the loop is truly closed. Pump seals, air vents, replacing corrosion coupons, filters, and routine sampling result in water and chemical losses which must be replaced. The sum of these leaks is normally minimal, and chemical additions on an annual or semi-annual basis can be considered normal. Water treatment chemical must be added to fresh water entering the system so it does not dilute the treatment chemistry to a level that reduces its effectiveness.
Abnormal situations where the loop is leaking or constantly losing water must be addressed quickly. This must be done to protect your closed loop system from corrosion, maintain water quality, and control water treatment chemical costs.
Leaks increase your costs:
- the cost of water — more water used
- the cost of energy — more energy used to heat or cool added water
- the cost of your water treatment program — more chemical needed to treat added water
It all adds up. Leaks can be costly! That’s why a make-up water meter is a great way to monitor your system and ensure leaks are minimized. When makeup water is added to the system, more water treatment chemical must be added to treat makeup water, driving up the overall cost of treatment. Fixing any leaks or water losses can reduce your overall treatment costs.
Your closed loop system should be tested regularly. If it’s truly closed once every one to three months should be sufficient. If it’s leaking regularly, or losing large volumes, you will need to increase the frequency of testing. It’s in your best interest to find and fix leaks as soon as possible to protect your closed loop and reduce overall maintenance and treatment costs.
Is Your Closed Loop Water Dirty? Are Filters Dirty or Plugging?
Unless your system is being cleaned, dirty closed loop water and filters may be signs of potential corrosion or other water quality issues. Detailed water testing by your water treatment supplier can help identify the source of the problem. In many instances, initial commissioning of these systems is done incorrectly causing lifelong system problems. Recommissioning may be required.
It is important to remember that any corrosion byproduct or precipitating impurities remain in the system indefinitely because the system is closed. Turbid water, which contains iron and/or calcium impurities can result in erosion corrosion or settle in low velocity areas or dead legs. An example of this would be super-enhanced tubes in chillers.
Filtration is the only effective way to remove these contaminants, however the filter must be properly sized and located to ensure a proper filtration rate relative to the total system volume. For example, a single 10-inch filter will not provide enough filtration for a 20-storey building.
Filters should be changed on a regular schedule established by your water treatment service provider. It’s important to observe filters for color and amount of loading on replacement. Any changes in color or loading may indicate problems that need to be addressed.
Depending on severity of water contamination and current treatment chemistry, most problems may be corrected without draining the loop. If cleanup efforts are required, this can increase the amount of water treatment chemical and your treatment costs.
Learn more about cleaning and protecting dirty and corroding closed loop systems in these case studies:
Is Your Closed Loop Used Year-Round or Laid-Up for a Period of Time?
Closed loop systems used year-round and in constant use may experience different results than those operated seasonally. Closed loops that are shut down in spring (heating) or winter (cooling) may benefit from more specialized treatments and shutdown/lay-up procedures. Stagnant water in laid-up systems can lead to corrosion issues. Your water treatment professional may recommend filming amine technologies or desiccant products to minimize corrosion damage during idle periods. In some cases, systems may be allowed to dry on their own or using fans.
Depending on water treatment chemistry and shutdown procedures, closed loop systems subject to seasonal shutdowns may experience increased operating and water treatment costs.
Materials of Construction, Heat Exchanger Surface Temperatures, and Flow Rates
Mild steel, copper, and aluminum are common metals found in closed loop systems. A properly designed treatment program utilizes specific corrosion inhibitors to address potential corrosion of each metal type at the heat exchange surface temperatures specific to the heating or cooling application.
Flow rates impact the potential for erosion corrosion due to the abrasive particulates. Low flow rates promote the settling of particulates which can accumulate and be difficult to remove. This can lead to scaling, under-deposit corrosion, and reduced/poor heat transfer.
This increases system operating costs due to the increased utility cost associated with reduced heat transfer. In addition, corrosion and scaling can reduce the lifespan of system equipment and components, result in unscheduled outages, and be costly to repair.
The Quality of Your Local Municipal or Well Water Supply
Most closed loop systems are filled from the local potable water supply. Water quality varies by geographical region. Particularly hard or corrosive waters may need special consideration in the selection of treatment products and application rates. Problems related to raw water quality are compounded when the system has leaks. This is due to the compound effect of high levels of impurities entering the system on a mass balance basis.
These impurities can affect the initial cost of treatment. If not properly treated, they can result in potential scale deposits, affecting heat transfer and increasing utility costs.
How Your Choice of Water Treatment Chemistry Impacts Closed Loop Treatment Costs
The most common closed loop formulations in the water treatment industry are nitrite, molybdate, phosphate, or silicate based. More recently, filming amines have proven to be a superior technology and are slowly growing in popularity. They are especially common in new closed loop systems and often used to clean and protect dirty or corroding systems.
Closed loop products also contain buffers to stabilize pH, dispersants to suspend particulates, and azole-based corrosion inhibitors to protect yellow metals such as copper. Products are also formulated to different market strengths which can affect the price dramatically.
Selecting the right product for your system that takes into account your unique factors is more important than the price due to the one-time nature of the purchase. The cost to replace components due to failure far exceeds the difference between the right product and the lowest cost product.
How Your Supplier Impacts Closed Loop Treatment Costs
Experienced water treatment suppliers assess your system and needs to determine the right water treatment solution for your closed loop heating or cooling system. Based on the factors above they can recommend the right water treatment solution for you.
Selecting a water treatment supplier requires consideration for all the treatment applications within your facility including steam boilers, cooling towers, water conditioning equipment, wastewater treatment programs and closed loop systems. You should also consider internal staffing levels and their ability to administer an effective water treatment program.
Many water treatment companies are capable of providing hands-on application assistance and a high level of automation which greatly reduces the need for your direct involvement in the application of the treatment program. This includes chemical addition, adjusting pump and controller setpoints, conducting routine water testing, moving water treatment chemistry to the point of application, and returning empty containers to meet recycling policies.
Your ideal supplier will have presence in your geography, be familiar with local water quality, and be capable of providing the level of service you require. Costs can be expressed per container or per month and include cost of labour, delivery, and treatment chemicals.
Automation, remote communications, and sensor technology can be used to reduce service frequency which improves program performance and reduces overall costs.
Optimizing Your Investment: Planning for Effective Water Treatment Costs
Though the cost of treating water within closed-loop systems can vary, it’s crucial to consider both upfront and operational costs. Some treatments might seem affordable upfront but have higher long-term maintenance costs.
Balancing initial cost with long-term investment is key. Remember, your closed loop system is a costly investment, selecting the right water treatment program will ensure you can rely on it for years to come. Best of all, proper water treatment will ensure optimal performance and substantial savings over time.
With this understanding, you can make an informed decision. An experienced water treatment service provider can ensure the most cost-effective and efficient solution for your closed loop system.
When you’re ready, contact us for your closed loop water treatment needs. With Chemistry Done Better, you can protect your closed loop system and Create a Better Future.