Circulation Pump WILO-Star RS 15/6

WILO circulation pump Technical Data

Data sheet of WILO-Star RS 15/6-130 standard pump
(WILO-Star RS_data sheet_download)

WILO OPERATION MANUAL Installation and operating
(WILO-Star RS_manual_download)
A circulation pump should be applied where the thermosyphon principle does not work, like in split heat pipe systems. A circulation pump is also needed in a flat panel system when the hot water tank can not be in-stalled higher than the panels, or when tank and panels are far away from each other.

A further application is for hospitality business when the hot water system should al-ways circulate in order to provide the user with prompt hot water supply rather than waiting a few seconds till the hot water reaches the tap. However here it is very impor-tant that the complete hot water system is perfectly insulated, otherwise the heat will lose within the walls and heating up the building them self.

Chiang Mai Solar using circula-tion pumps from the German brand WILO. The WILO-Star RS 15/6 pump is a glandless circulation pump for pipe in-stallation with manual 3-stage speed switch (46W, 67W or 93W). With blocking-current proof motor. Pump housing made from cast iron (bronze depending on type), impeller made from glass reinforced plastic and stainless steel shaft with metal-impregnated carbon plain bearings. Operational safety thanks to drilled-through shaft and filter unit in front of the cartridge.

Electric Back-up Heater

The climate change has a direct impact to the local weather in northern Thailand. 2010 and 2011 has already shown us periods with 2 or 3 days of continuous cloudy weather in a row. A condition quite unknown in the years before.

If a solar system is configured to small, or the hot water consumption is higher than normal, it would be possible to run out of hot water during such weather conditions.

A solar water heater still collects heat also during cloudy conditions from defuse light, but much less then during a sunny day.

Especially for a commercial application, like for a hotel, a back-up heating system would be recommended.

An electric back-up heater for your solar system could be oper-ated automatically by the computerized solar controller SR868C8. However, the case that you run out of hot water will be very rare. Therefore a manual switch with an indicator light would be enough to serve as an emergency heating system.
Chiang Mai Solar offers switches (16A) suitable to operate the back-up heater manually. Important is that the switch has an indicator light to signal that the heater is in operation, otherwise some will may forget to switch it off again. May one hour of heating gives enough heat to bridge the time till the sun will be back on duty.

Switch for Back-up Heater

Solar Controller SR868C8

The most precise way to control a sophisticated solar system is by a programmable logic controller (PLC). Such PLC has several time and temperature dependent functions, but mainly it compares the temperatures at the absorber and in the tank. Whenever the temperature at the absorber is higher than in the tank, the pump will circulate water. There are at least two sensors installed at the absorber and in the tank. A LCD display will inform about the stage of the actual process. This sophisticated technology makes the system highly efficient but in the same time require care during programming and during operation. Please refer to the controller manual for details about the full features of the controller.

Installation and Operation Manual for SR868C8 Solar Controller
(SR868C8_ENG manual_download)
Chiang Mai Solar is a brand of Oelmaier Technology Company Limited
40 Moo 2, Si Bunrueang Road, Soi 4, T. Nonghoi, A. Muang, Chiang Mai 50000, Thailand,
Technical Data
Main functions controller set

Digital Temperature Module

digital thermometer With this temperature module you can check the actual water temperature in your hot water storage tank. The module has a memory for minimum and maximum temperature and two switching output, optical alarm, frequency and buzzer output. (-10 to +110°²)

Operating Instructions

digital thermometer With this thermometer you can check the actual water temperature in your hot water storage tank.
• Range 0 to 120°C
• Size 58 mm x 44.5 mm
• Assembly hole 52 mm
• Capillary lenght 1.5 m

Operating Instructions

Analog Thermometer


flowmeterA flow meter will indicate the flow of water in the circulation circle. The flowmeter can be adjusted in order to reduce the flow.

Pressure Gauge

flowmeterA pressure gauge allows you to monitor the actual pressure and the fluctuation caused by expansion of the water. The pressure gauge is often used together with the expansion tank as it eases testing and adjusting of the air pressure in the expansion tank.

Small Pressure Pump

flowmeterIn a non-pressure system the resulting outlet pressure is depend of the gravitation, means the height between the tank and the faucet. A small pressure pump (e.g. 125 W) can be applied in a non-pressure system to boost the outlet pressure if necessary.

Automatic Thermostat

flowmeterThe automatic thermostat is mixing the hot solar water with cold water to provide safety and comfort at the faucet. The thermostat allows you to preset your preferred temperature and will maintain this temperature independent from fluctuations of the hydraulic pressure.

thermostat diagram thermostat temperature control knob

heavy duty system thermostat
thermostat diagram Automatic thermostats also help to prevent burns and injuries due to scalding. Solar heated water from flat panel systems can easy rise above 80°C , while solar water from heat pipe systems can even boil.

As the chart shows, burns from hot water can occur in just seconds - even less for small children. An automatic thermostat reduces the tem-perature at either the solar water storage tank (for the whole system) or at the fau-cet, so your family can use the sink, shower or tub without fear of scalding.

scalding table

Expansion Tank

An expansion tank being installed in the close pipeline can reduce pressure fluctuation caused by expansion of the water. In a pressurized solar system the water will expand during the heating process. In case there is no hot water consumption the pressure in the solar system will raise till the pressure safety relief valve would release the pressure. As a result hot water drops out of the relief valve. The expansion tank can reduce (but not eliminate) the peaks of such pressure fluctuations. Usually the expansion tank should have about 5% of the hot water tanks capacity (e.g. for a 240 litres hot water tank a 12 litres expansion tank is suggested). The air-pressure in the expansion tank should be adjusted a bit higher than the maximum pressure of the water supply (e.g. pressure pump). The air-pressure in the expansion tank need to be checked regularly and adjusted, if necessary.

Pressure Relief Valve

valves An automatic pressure relief valve is suitable to safeguard the pressurized solar water heater system in case of excess pressure, like from over heating. Installed on top of the hot water tank (indoor, type 1) or at the solar panel (outdoor, type 2) the valve will relief pressurized hot water when the pressure rises above the pre-set value.

Preset pressure settings are usually 3.5 bar or 4.5 bar.

For the indoor type (type 1) a discharge pipe should be installed to drain the discharged water. The end of the discharge pipe should be openly drained into a larger pipe which allows observing the amount of water.

Magnesium Rod

magnesium rod This is a rod made of magnesium that's formed around a steel core wire and can be screwed into the solar tank.

When the tank is filled with water, an electrolytic process begins whereby sacrificial anodes are consumed to protect a small amount of exposed steel. Electrolysis simply means that when two metals are physically connected in water, one will corrode away to protect the other. All metals fall somewhere on the galvanic scale of reactivity. When two are placed together in water, the "nobler" — or less reactive — one will remain intact while the more reactive one corrodes. When steel and copper are together, steel will be the one that corrodes. Indeed, steel is more likely to rust in the presence of copper than it would have been by itself. Magnesium is less noble than steel, which is why it is used for anode rods.

Solar water tanks from Chiang Mai Solar are build from high grade stainless steel, there is little in the solar system to corrode. However as a further option magnesium rods are available to fit into our pressure tanks. Remember, the anode is screwed into the tank. That means it can be unscrewed for revision and replaced if necessary. A sacrificial anode's life depends on the quality of the water, the water temperature, and the quality of the tanks as well — meaning how well we constructed our tanks.

Air Vent

air vent Small amounts of air may accumulate in a solar system by heating up the water in the solar collector. Placed close to the outlet at the highest point of the solar collector the air vent will allow the air to exit the system. Often needed in solar systems with forced circulation. When you mount the automatic air vent the shut off device opens. When there is no air in the inside the float rises closing the valve. When there is air in the inside, the float goes down allowing the discharge of air.