01 04 Insufficient circulation or low water pressure

What the control is telling you

Supply temperature rising faster than 27 °F per second, or return temperature rising faster than 27 °F per second.

Applies to: TRX150

Likely causes

• Low water pressure
• Air in the CH circuit
• Faulty temperature probe or pump

Test and repair steps

1. Press Reset to clear the code.
2. If it returns, check the water pressure on the gauge.
3. Purge air from the central heating circuit.
4. Check that the supply and return probes work and are positioned correctly.
5. Check that the circulation pump works and is positioned correctly.

Models that show this code

5 models in TRX

Other codes on the same units

• 01 01 Overheat (CH circuit)
• 01 03 Insufficient circulation or low water pressure
• 01 05 Insufficient circulation or low water pressure
• 01 06 Insufficient circulation or low water pressure
• 01 07 Insufficient circulation or water
• 01 08 Low water pressure lockout (water pressure switch)
• 1 10 CH flow temperature probe open or short circuit
• 1 12 CH return temperature probe open or short circuit