TL;DR
High discharge pressure is almost always fouled condenser tubes or non-condensable gas in the refrigerant circuit. Calculate approach temperature first, then clean tubes or purge non-condensables as indicated.
What you might see
- high condenser pressure alarm or trip
- condenser approach temperature above 2 degrees C
- reduced chiller capacity at same load
- increased compressor power draw
Likely causes
Fouled condenser tubes reducing heat transfer and raising condensing pressure
Non-condensable gases (air, nitrogen) accumulated in the refrigerant circuit, displacing refrigerant volume
Insufficient condenser water flow from a throttled valve, pump wear, or cooling tower issue
Condenser entering water temperature above design from poor tower performance
Required tools
- Chiller controls access (Trane Tracer panel)
- Tube brush cleaning kit
- Pressure gauge on condenser water system
- Refrigerant analyzer (licensed technician only)
Safety first
- Refrigerant handling requires EPA Section 608 certification. Never vent refrigerant to atmosphere.
- Drain and isolate the condenser water box fully before tube cleaning to avoid burns from condenser water under pressure.
Procedure
- 1
Read the current condensing pressure and condenser entering and leaving water temperatures from the Tracer panel.
- 2
Calculate the condenser approach temperature. Compare to the last tube-cleaning baseline. An increase of more than 0.5 degrees C indicates significant fouling.[1]
- 3
Verify condenser water flow by checking the condenser water pump differential pressure and comparing to the design curve.
- 4
Check the CenTraVac purge unit operation if equipped. Frequent purge cycles or a high purge runtime log indicate non-condensable gas accumulation.[1]
- 5
If tube fouling is confirmed, isolate and drain the condenser water box, then clean the tubes with a tube brush or hydraulic system. Document the tube condition.
- 6
If non-condensable gas is confirmed by the purge unit or by a certified technician using a refrigerant analyzer, have a Trane-certified technician recover the refrigerant, evacuate the system under deep vacuum, and recharge.
Warning: Non-condensable gas purging and refrigerant handling require EPA Section 608 certification. - 7
After correction, record the new baseline approach temperature for future comparison.
Sources
Trane CenTraVac Chiller Operation and Maintenance Manual, Trane (Trane Technologies)
Trane CenTraVac Operation and Maintenance Manual, condenser tube maintenance and non-condensable gas purging (general)
View source
More guides for Trane CenTraVac
How to fix high approach temperature on a Trane CenTraVac chiller
A rising approach temperature means heat transfer is degrading. On the condenser side this is almost always tube fouling. On the evaporator side it can also be low refrigerant charge. Calculate both approach temperatures from the operating log and address the affected side.
How to stop compressor short cycling on a Trane CenTraVac chiller
Short cycling at low load means the chiller is hunting around its setpoint or the system load is below the minimum stable capacity. Widen the chilled water setpoint deadband and check the inlet guide vane minimum stop.
How to diagnose frequent fault alarms on a Trane CenTraVac chiller
Multiple spurious alarms usually point to a single faulty sensor or a wiring issue sending bad data to the controls board. Cross-check each alarmed sensor reading against an independent instrument before replacing the controls board.
How to fix low cooling output on a Trane CenTraVac chiller
Low cooling output is most often a low refrigerant charge or fouled condenser tubes. Check the approach temperature across the condenser, read the operating log for refrigerant suction and discharge pressures, and contact a licensed refrigerant technician if charge is suspect.
Stop fixing the same fault twice.
Dovient turns guides like this into your team's shared playbook, with AI that catches recurring issues before they break the line.