Please refer to the solar controller handbook supplied with your pump station for sensor and relay allocation, these will depend upon the hydraulic arrangement of the solar circuit.

We supply two types of sensor, a high-temperature rated  sensor for use in the collectors (marked with /H on their part code on their packet) and lower temperature rated sensor for use in cylinders or heat exchangers.

For protection to -20°C use 40% concentrated fluid to 60% clean water.  If you use too high a concentration of solar fluid you will affect it’s heat transfer characteristics and also reduce the lifetime of the components in the solar circuit. Use a refractometer to check the dilution of your solar fluid.

The pump stations that we supply have a variable speed relay that regulates the pump depending upon temperature differential between the collector and the store. 

At the commissioning phase we would recommend that you run the pump in manual mode (100% speed) and record the flow-rate. In most systems you are looking for a design flow-rate of around 0.6 litres/minute per meter squared aperture installed.

Example

Two Barilla TZ20 Evacuated Tube collectors would require a design flow rate calculated below as:

Design Flow Rate =  (2 x Aperture Area) x 0.6 = (2 x 1.86) * 0.6 = 2.23 litres/min 

Flow-rates can be calculated using our Solar Thermal Design Assistant available in the Toolbox.

Firstly ensure that the system is cool and at rest prior to setting system pre-charge pressures. 

The system pre-charge pressure or gauge pressure depends upon the vertical distance of the pump station below the collector array. Allow 1 bar system pressure + 0.1 bar for every metre of vertical separation. E.g. the system pressure should be pre-charge to 1.5 bar where the collectors are 5m above the pump station.

The expansion vessel is supplied with a pre-charge pressure of around 3 bar, this should be adjusted to 0.25 bar below the system pressure. It should then be further increased by 0.1 bar for every meter of height the expansion is below the system gauge. E.g using the example above of a system static pressure of 1.5 bar and assuming the expansion vessel is 1m below the system pressure gauge, the pre-charge pressure of the expansion vessel is calculated as 1.5 – 0.25 + (0.1 x 1) = 1.35 bar.

System pre-charge pressures can be calculated using our Solar Thermal Design Assistant available in the Toolbox.

This will depend upon the hydraulic layout of the system. In most cases the factory defaults will suffice, however if you have a particularly complicated system or a long pipe run then please contact us for additional advice.

Please refer to the controller manual as supplied with the pump station. This normally involves setting the primary relay to ON rather than AUTO.

If the pump station is situated directly adjacent to the collector, the pump and expansion vessel membrane can be damaged by a stagnation event. If the pump station can only be sited adjacent next to the collector we would suggest running an elongated pipe run in an upward loop of at least 5 meters length between the pump station and collector to help arrest any “vapour-shot” that can occur during stagnation.

The three port vales that we supply have a permanent live feed, a switched live and a neutral. The live permanent feed (brown) should be attached to a nearby fused spur, the switched live (black) and neutral (blue) should be attached to the relevant relay on the controller (normally R2 on a C/Plus). Always check the controller manual supplied with the pump stations for relay relevant to the hydraulic arrangement that you are using.

The three port valve is used as a diverter either between a cylinder and a pool or between a cylinder and a heat dump. The solar flow should enter via Port AB, the primary demand (usually the cylinder) should be on Port A and the secondary demand or heat dump on Port B. In this arrangement when the relay is energised the valve moves to position B and returns to A when the relay is de-energised. If the permanent live feed is disconnected then the valve actuator will remain in the same place regardless of the relay state.

Most of the controllers that we supply allow you to prioritise flow between A & B or simulate parallel loading.

Use the same wiring and hydraulics as described in the three port valve question above. The main difference is that you also need to wire in a contactor to power-on the fan on the heat dump when the diverter valve is energised. The low-current part of the contactor can be wired in parallel with the three port valve on the switched live circuit.

The reason for this is that the relay supplied on the controller is low current, whereas the start-up current of a fan motor is much larger than can be delivered by the controller.