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Replacement Solar Hot Water Controllers
The controller is the brain of your solar hot water system. It reads the roof and tank sensors, decides when to run the circulating pump, and manages the electric or heat pump booster. When it fails, nothing else in the system works properly — even if the pump, sensors and collectors are all fine.
We stock over 80 controllers and replacement boards across the Senztek, RESOL, Aestiva and Reclaim ranges, covering most Australian systems built in the last 25 years.
✔ Signs your controller has failed
- No hot water and the pump never runs
- Pump runs constantly, including at night
- Blank, flickering or partially dead display
- Error codes that persist after sensors have been replaced
- Burnt smell, scorch marks, or audible relay chattering
- System overheating or repeatedly shutting down
✔ Choosing a replacement
Controllers are specified by how many sensors your system uses:
- 1-2 controller — 2 sensors (roof + tank)
- 1-3 controller — 3 sensors (roof + tank + inlet or second tank)
- 2-3 controller — flexible; works with either. Usually the safest choice if you're unsure.
Then match the family: Senztek SolaStat / SolaStat Plus / SolaStat ST Plus (solar circulation), Senztek AlphaStat Plus (electric booster control), Senztek SolaSmart, RESOL DeltaSol BS/4, BS/2, SLL, AL and AX, Aestiva 2 and 3 sensor, and Reclaim heat pump controllers.
Note: RESOL's DeltaSol BS/4 has been superseded by the DeltaSol SLL — we list the direct replacement alongside the original.
✔ Also available
Replacement boards, switching relays, covers, fuses, dataloggers and VBus interface adaptors — see Controllers Accessories.
✔ Why buy from us
- Controllers for discontinued and hard-to-find systems
- Direct-replacement advice when a model has been superseded
- Free thermal heat paste with most controllers
- Same-day dispatch before 3pm, free delivery over $150
✔ Need help choosing?
Email sales@solarhotwaterparts.com.au with your system brand and how many sensors it has, and we'll recommend the correct controller.
