Split Systems
We offer either flat plate or evacuated tube collectors with the split system. The split system, which requires a pump to move the glycol solution through the system, can either have an electrical or solar pump.
Examples of systems with the two different collectors are shown below. Both systems below have both
pump types, to illustrate the parts required for a fully functioning solar water heating system.
Flat Plate Collector
SANS 1307
Features:
• Toughened glass and durable copper waterway tubes
• EPDM rubber seals ensure durability and reliability in extreme climatic conditions
• Black chrome surface on copper substrate for max efficiency
• Housed in insulated aluminium to protect against physical damage.
Evacuated Tube Collector
SANS 1307
Evacuated tube collectors use two glass tubes, in between which a vacuum has been created. The outer glass tube and the vacuum within protect the absorbent coating and structural materials from corrosion. The absorbent coating is most often a thin layer of barium. The heat from the absorbent coating is transferred to the heat conveyance fluid. The fluid is an evaporating condensing liquid that evaporates in the collector tubes, and then transfers the latent energy (heat) to the cold water in the tank, through condensation. Heat transfer is always in one direction – from absorber to the tank and never the reverse. As each tube is independent, individually damaged tubes can be replaced with-out interference to the still-functioning system. Tube damage is indicated by the tubes turning white when the vacuum has been broken.
Below is a schematic representation of an evacuated tube type collector. Each company has their own, usually patented, evacuated tube technology; the drawings below are merely representations to explain the concepts.
Cross Section of Evacuated Tube Collector
Storage Tank
SABS 151
The Solartherm® products use a 2.5 mm Pex (cross linked polyethylene) lining to prevent corrosion and reduce maintenance.
The boiler material is internally welded 2.0 mm steel.
The casing is galvanized steel and is insulated with 25 mm high-density poly-urethane.
Split System Storage Tank
Pumps
The pumps are used to actively move the heated liquid through the collectors into the tank, to heat the household water.
Both pump types are illustrated in the figures on the sides:
Photovoltaic Pump
The photovoltaic (PV) pump requires more hardware and is more costly than the electric pump. However with a Direct Current (DC) pump, it is a carbon neutral solution, and can further reduce electric costs.
The advantages of the Laing pump are:
- soft start at very low in-rush current (soft start algorithm, less than 1 Watt required)
- economical and powerful
- long life, blockage free and maintenance free
- RF (radio frequency) suppressed
- protection against reverse polarity
- micro processor optimized flow
Electric Pump
The electric pump, which is less expensive and requires less hardware than the PV pump, runs off grid electricity, thus this system is NOT carbon neutral, and electricity cost reduction is lower.
- Housing from green cast iron.
- Impeller from polypropylene.
- Chrome high-grade steel wave with Grafit sliding bearings.
- All rotating parts are immersed in the fluid being handled.
- A shaft seal, being subject to wear and tear, is not required
- Fluid lubricates the shaft bearings and act as coolant to bearings and rotor.
- The pump is completely maintenance free.
Photovoltaic Panel
Photovoltaic panels use sunlight to generate direct current electricity. A 20 Watt peak panel is used to charge a 12 volt battery. This battery is used to drive the DC pump. A battery is required to ensure that the pump will run, whether there is sufficient sunlight or not. The PV panel will be mounted with the collector.
Controller for Split Systems
The controller box for the split system contains the following:
a. System controller – Main functions are:
- Clock display
- Temperature difference on/off
- Maximum tank temperature monitoring
- Frost protection
- Temperature controlled hot water circulation pump
- Time controlled hot water circulation pump
- Temperature controlled auxiliary heating during three time section
- Protection functions ( a. Memory protection, b. anti-bacteria protection )
The advantages of this system controller are:
1. Self power consumption: <3W
2. Measures temperature with-in 2 degrees accuracy.
3. Measurement range of 120 degrees.
b. Junction Box – Used to conceal and protect electrical junctions
c. Battery – The battery is a 12V 7 Amp battery
d. Charge Controller – Ensures that the batteries are not overcharged by the solar panels during the day and prevents the solar panels draining the batteries at night. The charge controller also prevents the loads placed on the batteries from discharging the batteries too deeply.
Expansion Vessel
Anytime the water pressure rises, it will push against the diaphragm and gently compress the air. The compressibility of the air cushions the pressure shock and relieves pressure in the system that could otherwise damage the plumbing.
The 24 litre vessel is made from high grade steel which is coated with epoxy. The bladder is made from butyl rubber.
Vacuum Breaker
Prevents water from draining out when the water supply to the system is cut off.
Temperature Pressure Valve
A Temperature Pressure valve is installed on a geyser. If the pressure inside the tank exceeds safety levels, the valve will drain water to relief the pressure.
Pressure Control Valve
The pressure control valve is installed in every house as a matter of course. It is required to ensure that all water is at 400 kPa.
