ASHRAE Handbook — HVAC Systems and Equipment, Primary-Secondary Pumping

ASHRAE Handbook — HVAC Systems and Equipment, Chiller Plant Piping

The condenser water return from the cooling tower is piped to the supply header instead of the return header. This reverses flow through the condenser, sending warm water from the tower back through the supply side. The chiller will see elevated condensing temperatures, causing high head pressure, reduced capacity, and potential high-pressure safety trips.

ASHRAE Handbook — HVAC Systems and Equipment, Cooling Towers

The basin heater thermostat has failed, not activating the heater in freezing conditions. Without basin heat, water in the sump and exposed piping will freeze, cracking the basin and potentially rupturing condenser water piping. Basin heaters must be verified annually before cold weather.

ASHRAE Handbook — HVAC Systems and Equipment, Heat Exchangers

Heavy scale buildup on heat exchanger plates indicates failed water treatment. Fouling reduces heat transfer efficiency and increases pressure drop across the exchanger. Scale deposits as thin as 1/32" can reduce heat transfer by 25%. The plates must be cleaned with an approved chemical descaler and water treatment program corrected.

ASHRAE Handbook — HVAC Systems and Equipment, Valves

Leaking 2-way valves allow chilled water to bypass through coils that should be off, reducing system delta-T. Low delta-T syndrome forces additional chillers online prematurely and wastes energy. Valves must be replaced or repacked. ASHRAE recommends close-off pressure ratings that exceed pump shutoff head.

ASHRAE Standard 188 — Legionellosis: Risk Management for Building Water Systems

Conductivity of 4,500 µS/cm is nearly double the upper target limit, confirming excessive mineral concentration. High conductivity accelerates scale formation, promotes corrosion, and creates conditions favorable for Legionella growth. Immediate blowdown is needed to reduce conductivity to target range.

ASHRAE TC 9.9 / TIA-942 5.3.5

Cables routed across perforated floor tiles obstruct cold air delivery to server inlets. Under-floor cable routing must maintain clear pathways around perforated tiles. Cable obstruction can reduce tile airflow by 50% or more.