RESOL DeltaSol BS/4 Pump Station (1-2 Sensors) — Replaced by RESOL DeltaSol SLL Controller

The RESOL DeltaSol BS/4 pump station (1-2 sensors) is no longer available. The RESOL DeltaSol® SLL Controller is the current direct replacement.

The DeltaSol SLL is the successor to the BS/4 and is compatible with the same open loop solar hot water systems. It is a 1-2 sensor controller suitable for standard flat plate and evacuated tube solar hot water systems.

Sensors must always be replaced at the same time as the controller — reusing existing sensors with a new controller voids warranty.

Suits a wide range of Australian solar hot water systems including Rheem, Dux, Hills, Rinnai, Chromagen, Apricus, Bradford Solar, Solahart, Conergy, Thermann, StratCo and more.

This is a complete solar hot water pump station replacement, not just a controller or pump.

If your solar hot water system is not working correctly, the pump station or controller is often the cause. This unit restores reliable circulation and temperature control for efficient system performance.

COMPLETE SYSTEM SOLUTION

✔ What this pump station includes

• Grundfos circulation pump (high-quality, reliable performance)
• Resol DeltaSol BS/4 1-2 Sensors Controller
• 1 x 20m roof sensor, 1 x 2.5m tank sensor  
• Thermal paste for sensor installation
• AVG or AW pumps unions (subject to availability)
• AVG or AW solar rated non return valve (subject to availability)
• AVG or AW Flow meter
• Quality pump station cover that can be fitted to a wall or it is moulded to fit onto the side of your tank
• Pre-wired components for easier setup

All components are matched to work together, reducing installation time and improving reliability.

✔ Common signs your pump station needs replacing

• No hot water or poor heating
• Pump not running
• System not circulating
• Controller not responding
• Intermittent or unreliable operation

✔ About the Resol controller

Resol controllers are widely used in solar hot water systems and are known for their reliability and advanced control features.

The DeltaSol range offers flexible system configurations, multiple sensor inputs, and precise control of circulation for efficient heat transfer.

This allows more precise system control and improved heat transfer compared to standard controllers.

✔ When this pump station is suitable

• Replacing an existing pump station
• Pump or controller failure
• Systems requiring full upgrade

Ideal for replacing older or faulty pump stations in residential solar hot water systems with improved efficiency.

✔ When it may NOT be suitable

• Systems requiring controller-only replacement
• Heat pump systems
• Electric booster-only issues

This allows better system performance, improved heat transfer, and reduced reliance on electric boosting.

✔ Controller Options: Aestiva vs Resol vs Senztek

We offer this pump station with different controller options depending on your system requirements:

• Aestiva: modern differential controller with smart heat management features, including overheating and stagnation protection. Ideal for users wanting advanced protection and efficient system performance.
• Resol: highly configurable controller suited to a wide range of system layouts, with flexible programming and multiple sensor inputs. Best for more complex or customised systems.
• Senztek: simple, reliable and widely used replacement controllers. Ideal for straightforward system repairs and standard solar hot water setups.

If you are unsure which controller is best for your system, contact us and we can help you choose the correct option.

The RESOL DeltaSol^® SLL controller is the replacement controller for the Resol DeltaSol BS/4, BS/2, BS Plus, AX and AL controllers.**