System Types
The book frames water treatment around a handful of recurring system types, each defined by how it moves heat and what enters, leaves, accumulates, and changes form inside it. This table covers the cooling and heating systems the book treats in chapters 11 through 13, from the open cooling tower to the boiler and its condensate loop.
| System | Purpose | Primary risks | Key controls |
|---|---|---|---|
| Open recirculating cooling (cooling tower, condenser water) | Reject building and compressor heat to the atmosphere by evaporating a small fraction of the recirculating water. | Scale on condenser tubes, corrosion of steel and piping, biofilm fouling, suspended solids settling in basins, rising condenser approach. | Cycles of concentration held by conductivity controller on blowdown, scale inhibitor, biocide rotation, sidestream filtration, tracer ion check (chloride versus calcium). |
| Chiller refrigerant loop (evaporator, compressor, condenser, expansion valve) | Lift heat from the chilled water loop into the condenser water loop through a refrigerant phase cycle. | Fouled or scaled condenser tubes raising lift, lost heat transfer, higher energy use, chiller unloading or shutdown. | Clean condenser surfaces, condenser approach temperature monitoring at full load, dependent on cooling tower performance. |
| Closed loop (chilled water) | Carry chilled water from the chiller to air handlers, fan coils, and process exchangers, then return it. | Corrosion (for example a leak at an expansion tank admitting oxygen), fouling that reduces heat transfer. | Sealed system with minimal makeup, tracing inputs and leaks with a free body diagram, inhibitor residual. |
| Feedwater tank and deaerator | Store hot feedwater and mechanically strip dissolved oxygen and gases before water reaches the boiler. | Cold operation raising dissolved oxygen, oxygen ingress through seals and packings, temperature paradox amplifying corrosion. | Live steam heating to boiling point (removes over 99.9 percent oxygen, below 10 ppb), venting noncondensables, oxygen scavenger as chemical insurance. |
| Pretreatment (softener, brine tank) | Remove calcium and magnesium hardness by ion exchange before feedwater enters the boiler. | Hardness breakthrough (most commonly an empty brine tank), scale on boiler tubes, tube overheating and failure. | Ion exchange resin regenerated with brine, brine tank salt level documented, feedwater hardness held below 0.5 to 1 mg/L. |
| Boiler vessel | Inject fuel heat into water to make steam, concentrating dissolved solids left behind. | Scale on hot tubes, under deposit corrosion, carryover through priming (mechanical) or foaming (chemical), water hammer. | Blowdown controlled by conductivity to hold highest safe cycles, TDS, alkalinity, and silica within ASME and ABMA limits, verified controller readings. |
| Steam and condensate loop | Deliver latent heat at points of use, then return hot, clean condensate to the feedwater system. | Carbonic acid corrosion of mild steel piping (pH dropping to 4 or 3), lost condensate, failed steam traps, water hammer. | Neutralizing amine blends raising condensate pH, film forming amines, steam trap audits, maximizing condensate return. |
Related concepts
Four Pillars of Water Treatment · Mass Balance · Cycles of Concentration · Corrosion · Scale · Microbiological Growth · Suspended Solids · Blowdown · Deaeration · Oxygen Scavengers · Carryover · Neutralizing Amines · Condenser approach temperature · Ion Exchange
Part of The Blueprint of Water