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Installation Instructions for the MOTORIZED Simple Pump System
(Scotch Yoke Drive option)
page 2

Recommended Operating Environment and Applications

Ambient Temperature

DC motors operating in ambient temperatures above 100 degrees F lose operating efficiency -- the hotter the ambient temperature, the less efficient. If the temperature at the planned site regularly peaks above 100 degrees F, we recommend operation of the motor in shade.

Consistent Source of DC Power

As with any DC motor, precaution must be taken to prevent operation under low voltage conditions -- below 11.5V with the 12VDC model, 23.5V with the 24VDC model.

Applications: What Works?

Ideal Application to Minimize Wear

Ideally, when pumping from any significant depth, you should not operate the Motorized System (Scotch Yoke Option) configured to pump into a pressurized system. The most difficult part of delivering water to a pressurized system is moving it out of the well. Once at ground level, the water can be delivered by a booster pump available at a fraction of the cost of the Motorized System (SYD Option). The only other additional cost is the tank for ambient storage, i.e., not under pressure.

The water lifted out of the well is pumped into the ambient storage tank by the Motorized System. Booster pumps designed specifically to pump into a pressure tank are available from a number of vendors, many for under $150 (US). The vendors who supply these include Dankoff, Surflo and Jabsco.

Configuring like this also raises the overall reliability of the system. Most notably, booster pumps include an integrated pressure sensor. It signals the booster pump to turns the pump on and off, according to a target pressure, when water is demanded from the pressure tank.

By contrast, any Simple Pump provides water in pulsed delivery, and therefore varying pressure, making the task of regulating flow to the pressure tank more difficult.

Unsupported applications

  • Operating the Motorized System in certain configurations voids its warranty.
  • Pumping into pressure greater than 50 psi.
  • Directly connected to batteries without a charge controller that prevents the supply of current below 11.5V or 23.5V, depending on whether the motor accepts 12VDC or 24VDC as input.

Supplying Power Reliably

The task of supplying power above the 11.5V and 23.5V (for 12VDC and 24VDC systems) thresholds is more complex than many anticipate, particularly with solar-powered systems. Because most configurations using the Simple Pump Motorized System are powered using solar panels, only solar is discussed in this section.

Keeping voltage above 11.5 or 23.5 volts seems simple: Provide enough power, with a device to regulate its delivery. However, a number of factors influence what constitutes “enough power” when considering how to configure an off-grid application:

  • Days of autonomy: The total number of days the system must provide power without sunny days, in the worst-case scenario. For example, if the system will be used throughout the year, with expected water usage the same throughout the year, the sunlight (hours and intensity) expected on the winter solstice is used to for the worst-case calculation.
  • Sunlight: Factor in both how far north (latitude) and expected cloud cover.
  • Daily water used. If more water is used when sunlight levels are higher -- e.g., more for gardening starting in March -- then projected water consumption must be compared against expected radiation at multiple points in time throughout the year.
  • Location: Separate from how much sunlight a location receives, those north of 45 degrees N (about as far north as Columbus, Ohio, should should also have a system that can be pivoted manually, to account for the sun’s much lower angle in the sky in winter.
  • Distance between power source and consuming machine.
  • Worst-case cold: If batteries are used, requirements can jump up to 1.6 times more than would be required in a warm climate.

Professional Help?

If this is more complex than you planned, there are alternatives.

Anyone with NABCEP (North American Board of Energy Practitioners) certification, and experience configuring off-grid systems, is almost certainly qualified to help. However, while all NABCEP-certified professionals must learn about off-grid systems, most pursue grid-tie solar systems -- a very different field. This is why it is important to ask about recent experience.

Contact Simple Pump if you want help finding a solar professional to assess your needs in the U.S. We do not have the expertise, but we can help you find it.


1140 Amarillo Drive, Gardnerville, Nevada 89460-7504