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Hi. My Potterton Suprima boiler stopped working- red light on constantly. I replaced the PCB with a new one. Then the boiler worked fine but no hot water. Heating working normally. S plan system. The water would only work if I put the 2 port valve on manually. So I changed the actuator - Danfoss HPA 2. Still same problem. Programmer set to constant, but actuator won’t come on automatically. Any suggestions please?
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Have you checked that power is getting sent from the programmer to the cylinder stat and then back to the zone valve?
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Programmer set to constant, but actuator won’t come on automatically. Any suggestions please?
Some possibilities, in order of likelihood:
  1. You made a mistake wiring up the new actuator.
  2. The programmer is mis-set or faulty.
  3. The new actuator is faulty or the wrong type.
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Thanks. I think I’ve fixed it! When the boiler broke down, I used the immersion heater in the Megaflo cylinder for hot water. The thermostat on this was set too high, and this tripped the thermal cutout on the indirect control. I pressed the reset button and all working fine now. Unnecessary change of actuator..

chris watkins

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You might want to get the Megaflo checked out because the maximum setting on the immersion control is 70deg C & the thermal cutout, as you call it, is 80-85deg C so something must have gone wrong for the water temperature to get high enough for the high limit on the indirect (boiler) side to have operated.
This is while Megaflo's need servicing along with the boiler.
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