The unvented cylinder in the SolarSmart system stores the water that is indirectly heated by the solar panel.

With a 90 litre capacity, the cylinder is smaller and lighter than most solar cylinders, and yet can provide enough hot water for an average family sized property. Because of its size, the cylinder is wall mounted and comes complete with a wall mounting bracket and a template to simplify installation.

Built in to the cylinder is a simple display indicating the temperature of water in the cylinder as well as the status of the system pumps.

The cylinder is fully G3 compliant, meeting all building regulation requirements and has WRAS approval. An unvented kit and expansion vessel are provided.

The Drainback Unit

The drainback unit has two functions. Firstly water from the collector 'drains back' in to the unit when the system is not in use. This protects against freezing, or in some circumstances, against overheating.

Secondly, water from the solar panel is used to heat a copper coil (heat exchanger) in the unit. Cold water from the cylinder passes through the coil and is heated before being pumped back to the cylinder.

The drainback unit comes pre-filled with water and is fully insulated to minimise thermal loss.

The Solar Valve

The solar valve is central to the whole SolarSmart system and ensures that the boiler is only ever used as a back-up and not to heat water when there is no immediate demand.

When there is demand for hot water, it is drawn from the cylinder and passes in to the solar valve which acts as a diverter valve. If the water is already at 60??C or more, it flows directly to the tap and the boiler doesn't need to fire. This is where a big proportion of the gas savings come from.

If however the water from the cylinder is less than 60??C, it is diverted to the boiler. Because the water will normally be preheated (by the solar part of the system), the boiler will modulate down and only have to operate at part load to raise the water to the required 60??C. So even when the system is using gas, it uses less.

The valve has flat washer connections and can be quickly fitted to any new or existing Alpha boiler.

Technical specifications

model	Dimensions(mm)	Weight (kg)	Water Content (litres)	Absorption Coefficient (%)	Return hose DBU (mm)	Flow hose DBU (mm)	Minimum roof slope (??)
SolarSmart 90 pack	2230x1120x92	41	1.3	94	12	15	20