Horstmann Centaurplus C27 Problems

A central heating system comprising of a Potterton Suprema HE boiler, Drayton thermostat, Horstmann centaurplus C27 programmer, a 3 port valve with a BGMVSP-23 actuator, and a BG Multi Head III pump is having trouble operating in Central Heating (CH) mode. The system doesn’t have issues in Hot Water (HW) mode, and it is suspected that the CH mode might also be relying on the HW mode to function. Key symptoms are:

• When the programmer is set to CH-only mode, there’s no heating, no pump operation, and the boiler does not turn on.
• In HW-only setting, everything seems to work fine, with the boiler lighting up and the pump running.

Potential Solutions:

1. Check the Actuator’s Synchron Motor:
   • The synchron motor could be malfunctioning, preventing the valve from switching to the CH position.
   • Removing the power head and checking if the spindle is seized could reveal any issues here.
2. Actuator End Switch Issues:
   • If the actuator’s end switch isn’t working, it could be due to the valve body starting to seize or due to the switch contacts failing.
   • This issue will result in the pump and boiler not operating in CH-only mode. But, they would work when HW is in demand because the end switch doesn’t play a role in this scenario.
3. Valve Position Check:
   • Manually rotating the valve by about 20 degrees could determine if it’s functioning correctly. If it rotates with manual power and is in the mid-position, the valve could be alright.
   • If the radiators heat up even when set to HW-only, the valve being in the mid position would be expected.
4. Check Wiring and Control Logic:
   • Incorrect wiring could lead to inconsistent operations of the heating system.
   • The proper functioning should be:
     • Hot Water only = valve at rest in hot water position with boiler and pump controlled via the cylinder thermostat.
     • Hot Water and Central Heating = valve in mid position or fully open depending on cylinder thermostat position.
     • Central Heating only = valve fully open to the heating position with the boiler and pump controlled by the room thermostat via the valve end switch.
5. Consider Replacing the Actuator:
   • If the actuator is not functioning correctly, replacing it could resolve the issue. Opting for a well-recommended model, like the Drayton MA1, could be a viable solution.

Conclusion:

Central heating systems can sometimes pose challenges due to the interplay of multiple components. If you face issues with your Horstmann CentaurPlus C27 programmer, considering the solutions mentioned above could help. As always, for complex problems, it’s recommended to consult with a professional technician to diagnose and rectify the issue efficiently.