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723 Description Zone 3 overheating.
Cause: The Zone Manager ST3 overheat thermostat has overheated. **Note** if 2 zone managers have been used
together, the fault may be in either zone manager and is not individually defined.
1. Check the link and its connection to the "ST3" terminal block on the module.
2. Check the maximum heating temperature setting for Zone 3 or 6 via parameter 6.2.5 or 16.2.5.
3. Check the connection of the safety thermostat to the "ST3" terminal block on the module.
4. Check the wiring harness and connectors if a safety thermostat is in use. Replace as required.
5. Check for continuity over the thermostat and replace as required.
6. If the above is all ok, replace the zone manager.
750 Description ZM undefined hydraulic scheme
Cause: Issue with the zone manager hydraulic settings.
The zone manager(s) need defined. Use parameter 7.2.0 for zone manager 1 and parameter 7.5.0 for zone manager
2. Use the guide below to set correctly.
0 = Not defined - DO NOT USE.
1 = N/A – DO NOT USE.
2 = Mixed heating circuit module II.
3 = Mixed heating circuit module III
4 = N/A
5 = Direct heating circuit module II
6 = Direct heating circuit module III
Heat Generation Lock
Cause: External safety contact open circuit.
1. Check the link wire in the white connector (External safety contact) volt free connection on the side of the
PCB. If missing or damaged, replace the connector and link.
2. If a condensate pump safety switch has been wired into the white connector, check the operation of the
condensate pump discharge.
3. Check the condensate pump is discharging and the float is moving freely.
4. Check the safety switch of the pump. Free off or replace pump as required.
5. Check the cables and connectors from the condensate pump to the boiler. Use a multimeter to confirm
continuity. Replace as required.
6. If the above is all ok, replace the boiler PCB.
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