Questions Regarding All Dankoff Solar Pumps
1. In what type of environment should I install and keep my pump?
A: Dankoff Solar Pumps are not submersible. They can tolerate occasional water splash, but must be protected from extreme wet conditions including rain. The motors require some air cooling; please allow air space around the motor. Do not wrap insulation around it. Provide coverage from rain and direct sun too. If freezing is to be expected, remove the pump or drain it for the winter season. Every Dankoff pump comes with a detailed instruction manual. Please read the manual thoroughly before installation. You can download it in advance from this web site on the Resources page.
2. Do your pumps require a controller?
A: Pump controllers are required for all positive displacement pumps when used without a battery (PV array-direct). All but the SunCentric Dankoff pumps are positive displacement. This means they begin to force water the moment they begin to turn. A solar array without a controller (or battery) will be unable to provide the current to start or run the pump unless the sun is very bright. It may not start until mid-day. A controller acts like the transmission in a vehicle. It lowers the voltage and raises the current to run the pump, however slowly, in low-light conditions – like shifting to low gear. The controller also protects the motor from overload and over-speed and provides low-power float switch control. Controllers will increase system performance approximately 30% over the course of one year!
3. Why are your motors brushed?
A: Dankoff Solar Pumps are designed for industrial reliability at the lowest cost. All of our pumps use brush-type motors for simplicity and economy. Brushes are a wearing component, but brush life generally exceeds 10 years (some SunCentric models may average 5 years due to higher speed). Brushes are easy to inspect and replace, taking just a few minutes. Our instruction manuals have further advice on predicting brush life and replacing them. A brush motor offers great simplicity and low cost because it runs from DC power directly with no need for conversion to AC. We have investigated brushless motors but they cost much more and are not of great advantage for surface pumps.
Our SunRotor Submersible pumps DO use brushless motors, so the motor can be oil-filled and submersed in water. For submersibles, brushless is a great advantage.
4. Do you have any pumps that can handle hot fluids?
A: High Temperature versions of SlowPump (up to 190 °F / 88 ° C) and SunCentric (up to 240° F / 115° C) models are available. Common usages for High Temperature models include lubrication, as well as Geothermal and Solar Thermal fluid transfer/circulation.
5. Regarding the Solar Slowpump and Flowlight Booster Pump: When the Dry Run Switch trips and turns off the pump, does it reset automatically?
A: No. There is a manual reset button on the face of the Dry Run Switch. It does not turn back on automatically to ensure the running dry problem has been corrected. An automatic restart has too much potential for ruining your pump, as it would keep cycling and eventually destroy itself.