Applies to: CW‑H10, CW‑H15, CW‑H15S, CW‑H15S Plus (Multi‑Magic control system)

1. Overview

Cooling shortfalls in CW‑H systems are most commonly linked to airflow balance, water distribution, core sealing/fitment, or commissioning/configuration issues. This guide walks technicians through a fast, structured diagnosis with links to the relevant manual pages.

2. Common Symptoms

• Supply air temperature only slightly cooler than ambient.
• Warm air leaking around core doors or into the supply duct.
• Weak/unstable airflow, or water spitting from the top exhaust.
• Excess humidity, or DEC stage not engaging (Supercool models).

3. Critical Initial Checks

3.1 Confirm the Unit Is in the Correct Cooling Mode

• Ensure the cooler is not in Vent Mode (Controls → Control Screen). (p.18–19).
• Confirm the correct primary control method is selected: Local / Wall / BMS / Modbus / BACnet. (p.18–25).
• Check and clear any active fault codes via PLC (and review fault history if needed). (p.28–29).

3.2 Understanding IEC vs DEC (Simple Explanation)

IEC – Indirect Evaporative Cooling (ALL CW‑H models)

• Air is cooled by passing through “dry” channels of the heat exchanger while water cools the adjacent “wet” channels; the supply air does not touch the water, so it stays cool and dry. (Technical description & airflow, p.9).

DEC – Direct Evaporative Cooling (Supercool variants only)

• A second stage that uses wet pads (Chillcel) to boost cooling further, adding a small amount of moisture to the air. (Direct stage description, p.9; Supercool configuration & setup, p.13).

Which models have DEC?

• DEC present: CW‑H15S, CW‑H15S Plus (Supercool models). (p.9, p.13).
• IEC‑only: CW‑H10, CW‑H15. (p.9).

How to identify DEC in the field:

• Chillcel pads visible in the supply outlet section (Supercool only). (p.42).
• PLC → SETUP → DEVICE TYPE shows CW‑H15S or CW‑H15S Plus if DEC is fitted. (p.13, p.31).
• Supercool models also have a direct (DEC) pump in addition to the IEC pump. (p.17; pump layouts p.38).

4. Airflow & Duct‑Related Causes

4.1 Incorrect Plenum Pressure (Most Common and therefore the most critical check)

Correct plenum (supply transition) pressure is essential for the designed split between supply and exhaust. Target pressures (at Speed 10):

• CW‑H10 → 200 Pa
• CW‑H15 → 175 Pa
• CW‑H15S → 175 Pa
• CW‑H15S Plus → 210 Pa
  (Air Flow Balancing procedure). (p.32).

How to set it:

• Run LOCAL → IEC → Speed 10; allow ~5 minutes for first fill and pump cycling. (p.25, p.32).
• Measure via the manometer port on the transition and adjust the damper to achieve the model‑specific Pa. (p.32).

If pressure is wrong, expect: reduced cooling, exhaust spitting/water carryover, unstable temperatures. (p.32, p.43).

4.2 Restricted / Closed Ducts

• Don’t run against closed supply air ducts; ensure dampers/outlets are open. (p.11).
• Check for undersized ducts and excessive bends raising static pressure. (p.11–12, troubleshooting p.43).

4.3 Insufficient Building Relief

CW‑H uses 100% outside air; the building must relieve an equivalent volume to outside. (p.11).

5. Water System & Saturation Issues

5.1 Water Flow or Filling Problems

Verify water system health:

• Supply pressure 100–800 kPa and adequate flow. (Water requirements p.15).
• Inlet solenoid opens and tank reaches high probe. (Water management p.17; commissioning checks p.31; solenoid service p.38).
• Strainers/filters clean; probe clean and reading correctly. (p.38–40).

5.2 Pump Not Running / No Circulation

• IEC pump duty cycle (1 min ON / 8 min OFF) during IEC mode. (p.17).
• DEC pump runs continuously in DEC mode (Supercool only). (p.17).
• Confirm operation using SERVICE → TEST MENU. (p.37).

5.3 New or Unflushed Cores

New heat exchangers can cause foaming/pull‑off. Perform Heat Exchanger Flush during commissioning. (p.31).

6. Core Condition & Sealing Problems

6.1 Misaligned Cores or Spreaders (Air Bypass)

If cores/spreaders shift or are not seated properly, air bypasses the cooling surfaces and performance drops.

• Inspect core seating; butt cores tightly with no gaps.
• Ensure spreader trays locate into the front extrusion, and clamp strips capture the rubber extrusion correctly.
• Doors must compress the seals evenly when closed.
  (Heat exchanger removal/refit & sealing details p.41–42).

6.2 Core Fitment / Door Seal Inspection

Even when installed correctly, uneven seal compression or small fitment variances can create air‑bypass routes.
Check for:

• Daylight or airflow leakage around door perimeters.
• Core not sitting square on its platform.
• Rubber extrusion not compressed evenly by the clamp strip.
• Door seal not contacting the full core face.

Corrective actions: re‑seat cores, refit/tighten clamp strips, confirm door seal contact, and apply standard field sealing (e.g., foam strip/gasket) where appropriate. (General fitment & sealing references p.41–42).

7. Controls & Configuration

7.1 Verify Correct Device Type (Supercool Models)

If the PLC Device Type is wrong, the DEC stage will not operate on Supercool units.

• SETUP → DEVICE TYPE and select CW‑H15S or CW‑H15S Plus as applicable. (p.13, p.31).

7.2 Wall Controller & Sensors

• Wall Controller setup & node addressing. (p.20).
• Sensor configuration/reading (Ambient/Room/Duct/Pressure). (p.19).
• Check setpoints, humidity limits, schedules, and sensor placement. (p.18–21).

8. Fan/Motor‑Related Issues

• Fan/VSD control & expected behaviour. (p.17–18).
• If fan cannot reach commanded speed, verify static pressure, wiring, and motor status on Monitor screens; see Troubleshooting. (p.19, p.43).

9. Quick Troubleshooting Checklist