PROBLEM: High-rise buildings, built in 1960’s, were experiencing scaling, bio-film and dirt (rust) deposits in their condenser water systems. This inhibited heat transfer, lowering HVAC hydronic system efficiency. Previous traditional solutions (chemicals & flushing) failed to stop the cooling towers and chillers from scaling up. This required that they be opened and cleaned frequently.

Scale and corrosion on chiller head
Scale and corossion on chiller head
called chiller tubes
Scale and corossion on chiller tubes

DISCUSSION: Scale build up on condenser water tubes can significantly reduce the overall efficiency of the chiller. A mere 0.032” thick layer of scale will reduce the heat transfer efficiency by 30%. Bio-film and corrosion also lower efficiencies even further, costing $100 or more, per ton of cooling each year in excess energy usage. The chiller plants were seeing a minimum of 0.032” of coatings with some tubes partially blocked from debris.

table of energy loss in chillers due to scale and rust

SOLUTION: SweepCLEAR air & dirt separators (10” & 12”) were retrofitted to the condenser water systems to remove microscopic air and dirt from the full flow of water coming from the cooling towers. Automatic blow-down & air release valves were included to purge the tank of collected air & dirt, making the separators maintenance free.

sweepCLEAR installed in air separator
sweepCLEAR installed in air separator
hydroFLOW water treatment
hydroFLOW installed on condenser pipe

Four months later HydroFLOW Water Treatment Systems were installed on the condenser water pipes to remove and prevent scaling, bio-film, bacteria, and corrosion. Note: SweepCLEAR separators are required to remove the “solids” generated by HydroFLOW.

hydroFLOW schematic

RESULTS: SweepCLEAR separators have already proven to stop corrosion and fouling on hot, chilled and loop hydronic systems. Now, after operating 18 months together with HydroFLOW technology, cleaning and protecting the high-rises’ condenser water systems, the chillers were opened for annual inspection. The maintenance staff noted tubes and heads looked “exceptionally clean” with NO fouling present. The water pushed from the tubes was clear, not “muddy” as usual. The heads & piping appeared polished with a metallic silver & black protective coating, from the magnesium anodes and magnetite generated by the HydroFLOW unit. Estimated energy savings per year from“zero” scaling was $62,000 (ROI in 11 months)! Additionally, there will also be huge savings of water (from reduced blow-down), chemicals, maintenance, and capital equipment.

Scale Free Chiller Tubes & Heads (Heads Coated with Magnesium &
Scale Free Chiller Tubes & Heads (Heads Coated with Magnesium &

Miles of wire are rolled into coils and placed inside a TAS. It is the fine wire (0.027” diameter, 304 SS welded wire mesh) that allows SweepCLEAR to remove 99.5% of the air (free, entrained and dissolved) and dirt molecules in the water through a process called “molecular adhesion “. Once the water is clean, corrosion and fouling will stop – typically in 30 days or less. Free floating particles in the water want to stick to a surface as opposed to staying in the water as they pass through the separator tank. WIKI states the “coalescing” media “scrubs” the air and dirt from the water. Coalescing means, come together – the small particles on the wire mesh want to stick to each other, resulting in bigger particles. The air bubbles grow large enough to float off the wire and out of the top of the tank.

sweepCLEAR micro bubbles
sweepCLEAR micro bubbles

The large dirt particles fall off the wire and sink to the bottom of the tank. The more wire in the tank the better the process works. BUT you do not want to block the water flow through the tank or the pressure drop will increase, wasting energy. Many of our competitors attach the wire to large diameter pipes that seriously block the flow. SweepCLEAR has 2.2 times more wire in the tank than any competitor, yet only fills the tank 2% by volume, resulting in a 5% increase (negligible) in pressure drop. And since we use TAS (tangential air separators) the pressure drop is very low to begin with – at 10 fps (high velocity) the pressure drop will not exceed 1.4 feet! See the attached TAS cut sheet pressure drop curves and pipe velocity chart.

pressure drop chart
velocity to GPM conversion

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