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Important information on the testing & validation of low water level safety system


Spirax Sarco Building

At Spirax Sarco, we highly value quality and safety. As such, we have updated our LP40 & LCS3050 Installation & Maintenance Instructions (IMI) to reinforce good engineering practise and we would like to make you aware of these material changes. To supplement these updates, please refer to the Switchpoint/Evaporation Test Instruction guide.

When using an LCS3050 and 2 x LP40 probes, it is vital that during commissioning and also when performing the regular functional tests, there is a visual inspection of the status LED's on the LCS3050 controller itself.

Historically, functional tests, often referred to as evaporation tests, are performed by manually lowering the water level to obtain 2 outputs: shut down of the burner and system alarms, both audible and visual on the control panel (the specifics will differ between sites).

This was an acceptable approach due to the probes operation; 1 probe as a 1st low (shut down the burner) and the 2nd probe as the 2nd low (lock out), each probe having their own controller.

With the LP40/LCS3050 system configuration of 2 x probes and 1 controller, this is no longer an adequate approach to testing as both probes operate as a 2nd low and lock out the burner.

The 2 probe system acts as a safety redundancy. In the scenario where 1 probe fails for any reason, the 2nd probe will perform the same 'lock out' function ensuring a safe boiler system. 

To fully validate the safety features and dual probe configuration, the LCS3050 must be visible during the testing. The controller uses LEDs to visually demonstrate the operational functionality of the probes and these need to be visible (or connected to auxiliary LED’s) and checked during the test.

If the controller is NOT visible, the burner may still shut down, alarms will sound as before, but there will be no certainty that both probes are functioning correctly. The output could be from only 1 probe with the other malfunctioning unknowingly.

Therefore, the only way to be confident that both probes are fully operational is to witness the LEDs illuminating as per the evaporation test instructions (found in the link below).

Technical documents