In a direct flow open loop solar hot water system in Australia, both solar panels and water tanks are pressurized by the mains supply. The pressurized water is present in the solar panels even when the pump is not pumping. Only a low power circulation pump such as Grundfos 15-20 CIL2  is required in such systems. The pump's job is only to overcome the friction and bends in the pipe work, but not to pump heads. Many customers ask if this pump can pump water from wells or swimming pools or saunas to the solar panels. The answer is no, as a more powerful pump will be required to pump heads in these applications.

Due to its relatively low cost and reliability, The Grundfos 15-20 CIl2 pump is a also a popular replacement solar pump to Grundfos single speed UP15-14B PM pump used in Dux and Rinnai.

The Grundfos 15-20 CIL2 pump features 3 power settings of 20W, 25W and 30W for the added flexibility. The pump is IPX4 tested for weather resistant in outdoor conditions. The Grundfos 15-20 CIL2 pump is supplied with a 500mm pre-installed electrical lead with a standard 3 pin plug for a hustle free plug-play style installation.

- A solar rated check valve MUST be installed above the pump to protect it from the solar panel's back flow. During warranty claims, the photo of the installation MUST be provided to identify this check valve or the warranty will be denied. The back flow in summer from the stagnant solar panels can reach up to 180 degrees for flat plates and 220 degrees for evacuated tubes. Without the check valve, the back flow will burn and deteriorate the internal pump seals. It will appear as a leaky pump if the water chamber seal is broken or it will appear as an electrical fault if the electrical motor side seal is compromised. All Plumbing Online recommends AW or AVG solar check valves, sold separately or as kits with this pump.

Series LF009 reduced pressure valve assembly backflow preventers are designed to prevent the reverse flow of liquids in a plumbing system due to backpressure or backsiphonage where there is a potential health hazard. Their compact modular design makes them easy to install in tight spaces and the single cover, top-entry design allows convenient access for maintenance. The seats are replaceable for economical repair and no special tools are required for servicing. Available in sizes 1/4 - 3 inch.

Series LF009 reduced pressure valve assembly backflow preventers are designed to prevent the reverse flow of liquids in a plumbing system due to backpressure or backsiphonage where there is a potential health hazard. Their compact modular design makes them easy to install in tight spaces and the single cover, top-entry design allows convenient access for maintenance. The seats are replaceable for economical repair and no special tools are required for servicing. Available in sizes 1/4 - 3 inch.For 2 1/2 and 3 inch sizes: the coating on this backflow assembly uses ArmorTek™ technology to resist corrosion due to microbial induced corrosion (MIC) or exposed metal substrate.

This Grundfos 15-20 CIL2 solar hot water pump by All Plumbing Online is supplied with a pair of AVG pump unions. The AVG pump unions reduce the pump's BSP 1" thread to 1/2" with compression fittings, which can readily screw to other valves/fittings as a male thread or be connected to standard 1/2" copper pipe. The AVG pump unions' loose nuts make future pump extraction easy during a service or replacement, without needing to touch other connected plumbing works.

- For most installations up to 2 story house, speed 1 is sufficient. Spead 2 or 3 is only needed for 3 stories or extra long pipe runs. The idea is to achieve 1-2L/min flow rate with minimum power setting. During my engineering work for Apricus and many other solar hot water manufacturers, this flow rate is found to be most efficient due to the laminar flow property of the water and hot water stratification effect in the water tank. A faster flow will cause turbulence inside the panel's pipe work reducing the heat transfer. A faster flow will also stir up the water tank more, causing the colder water at the bottom to mix with the usable hot water at the top, reducing the overall hot water delivery. A flow meter is sold separately or as a kits with the pump by All Plumbing Online and this can set the flow right for best efficiency.

-The Grundfos 15-20 CIL2 pump propeller shaft bearings are water lubricated and must be parallel to the ground level. It is ideal to run the pump vertically, with the water flow from bottom to top. When running the pump left to right, the bearings may be at risks of being starved of water lubrication and wear out prematurely.

All Plumbing Online is a local business based in Brisbane, run by an experienced engineer who works as a consultant to the plumbing industry at manufacturers' level. I used to operate my own plumbing company also and can answer any of your plumbing related questions, such as fitments, sizing or just chatting in general for advice. Feel free to drop me an Ebay message.

For 2 1/2 and 3 inch sizes: the coating on this backflow assembly uses ArmorTek™ technology to resist corrosion due to microbial induced corrosion (MIC) or exposed metal substrate.

The Grundfos UPS 15-20 CIL2 solar hot water 3 speed circulation pump is designed from ground up as a low energy and high efficiency solar pump suited to Australian market's open loop solar hot water systems. The Grundfos 15-20 CIL2 solar hot water pump is one of the most common oem solar hot water pump used in Australia in many pumped solar hot water systems offered by Apricus, Chromagen, Neopower, Aestiva and Therman.