Plate Heat Exchanger Troubleshooting Guide

Common Faults and Solutions

1. Fault Indicator Light is ON

Cause: Motor current exceeds rated value, thermal relay protection activated.

Solution: Press the reset button and wait for relay to cool before resetting.

2. System Has Pressure but Gauge Shows 0

Cause: Needle valve connected to pressure gauge is closed.

Solution: Ensure all needle valves are fully open during operation.

3. Secondary Side Overpressure

Cause: Water expansion after temperature rise increases system pressure.

Solution: Release air and drain water; pressure stabilizes as temperature stabilizes.

4. How to Identify Filter Blockage

• Primary Side: Large temperature difference, secondary not heating. Check and clean filter.
• Secondary Side: Large temperature difference in secondary loop, low pressure difference. Check and clean filter.

5. How to Identify Heat Exchanger Blockage

Symptoms: ΔP > 0.15 MPa, secondary supply temperature low.

Solution: Disassemble and clean the heat exchanger.

6. System Not Heating

Primary Side Issues: Insufficient flow, valves not fully open, filter blockage. Check valves, clean filters. Adjust flow according to ΔP.

Secondary Side Issues: Poor circulation, blocked filters, heat exchanger blockage. Check circulation, clean filters, and disassemble exchanger if necessary.

7. Make-up Water Cannot Enter System

Symptoms: Pump running but pressure not increasing.

Cause: Air trapped in system.

Solution: Perform air venting.

8. Variable Frequency Make-up System Not Working

Check switch is set to Auto/Variable Frequency and pump is running (green light ON). Check inverter alarm codes: “F” = Fault → reset; “R” = Warning → does not affect operation.

9. Secondary Supply Temperature Too High

Solution: Throttle primary supply valve, keep return valve fully open.

10. Excessive Pump Noise

Causes: Mechanical wear, air in pump, loose components.

Solution: Vent the pump, check fan cover, perform regular maintenance (lubrication, parts replacement).

11. Frequent Make-up Water & Pressure Drops

Possible Causes: Leakage in secondary system, faulty check valve.

Solution: Inspect pipelines and valves, replace leaking check valve.

12. One Pump Runs, the Other Rotates Backward

Cause: Check valve failure → backflow.

Solution: Replace check valve, temporarily close inlet/outlet valves.

13. How to Check Pump Rotation Direction

Use a clamp meter. Correct rotation = higher current than reverse rotation.

14. Pump Indicator ON but Pump Not Running

Solution: Check circuit breakers in control cabinet; ensure all breakers are switched ON.