Closed Loop

Efficiency Begins From Within

The Closed Loop Treatment Program uses field-proven products and services that protect components from corrosion, improve system performance, save on energy consumption, and reduce GHG emissions.

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What is a Closed Loop System?

Closed Loop heating and chilled water systems circulate water through a piping system intended to heat and cool a building. “Closed Loop” implies the recirculation of the same water, typically requiring little to no makeup water following the initial system charge. 

However, even small unexpected water leaks can introduce corrosive elements, such as oxygen, that degrade these systems.

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Problems in Closed Loop Systems

Corrosion, scale, fouling and microbiological growth are considered the four major problems in all types of circulating water systems. In Closed Loop systems, corrosion stands out due to the introduction of dissolved oxygen from the raw water makeup. 

Dissolved oxygen causes mild steel and iron to corrode rapidly, releasing small flakes of rust into the recirculating stream. Abrasive particles erode pump seals, cause leakage, reduce heat transfer efficiency and block pipes. The result is expensive equipment replacement and excessive downtime.

Closed Loop System Solutions

The Closed Loop Treatment Program is designed to economically improve operations while decreasing the carbon footprint. We identify and eliminate the source(s) of significant water loss, protect system components from corrosion, improve heat transfer efficiency, save on energy consumption, and cut GHG emissions. 

The program includes our on-site testing services, e-Service Reporting, and implementing a film-forming corrosion inhibition treatment that provides excellent corrosion rate protection as recommended by the Association of Water Technologies (AWT).

The Closed Loop Treatment Program works in tandem with our energy saving program, EndoTherm®, to reduce the surface tension of the system water, increase heat transfer, optimize energy gains and lower fuel cost/usage.


Rising HVAC Energy Bills

Managers of an office building with a closed loop heating/cooling system were seeing a gradual rise in energy costs and continual pump seal failures. After experiencing HVAC downtime, they figured out the system had poor water quality and had depleted efficiency due to system water leaks.

Treating the Cause

Pace specialists identified issues with inadequate corrosion protection, excessive suspended solids and leaking pump seals. Technicians created a service schedule and initiated a corrosion inhibition program and by-pass filtration, then add EndoTherm® treatment to improve efficiency.

Lower Bills, Fast Simple Payback

Leak maintenance was performed: the system was flushed with PURGEX cleaner, protected with BAR COR corrosion inhibitor, then treated with EndoTherm® energy saving additive. Managers reported more even heat throughout the building, a significant reduction in energy use, lower GHG emissions, and a simple payback within 2 years.



How can I tell if I have leaks in a closed loop system?

If leaks are suspected, installation of an inexpensive totalizing water meter in the make-up line will provide early detection. Regular testing of the water can also detect leaks.

Why does a closed loop system need a filter?

The fluid in a closed system usually contains a suspension of fine, abrasive particles which are harmful to equipment (i.e. pump seals), and leads to unscheduled shutdowns and increased maintenance. There are various sources of these particles, mostly resulting from corrosion. Side stream filtration and scheduled filter changes are necessary to minimize the risk of damage.

Do we require a different treatment program for boilers that contain aluminum?

Yes. Boilers manufactured with aluminum or stainless steel heat exchangers are extremely sensitive to the high pH levels used in traditional closed loop treatments. Typical closed loop treatments inhibit corrosion using pH buffering, and it is not uncommon to operate at values from pH 9.0 to 10.5. Aluminum starts to degrade rapidly at pH values above 8.5 and stainless steel at pH values above 9.0. Consult with your Pace Technical Representative for the specific corrosion inhibitor treatment recommended for your heating systems with aluminum or stainless steel metallurgy.

Should the water be clear in a closed loop system?

Closed loop water should be almost clear and colourless. Dark brown or black water indicates a serious corrosion problem. There should be very few solid particles collecting at the bottom of the sample container. Consult with a Pace Technical Representative in your area for further analysis to determine the water quality.


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