Solar Hot Water Pumps FAQ'SSolar hot water circulating pumps can be used for many different projects. Understanding the technical aspects of how they work can help you to troubleshoot problems or understand what is the pump for your needs.

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What is Static PSI/Bar?


It’s important to understand PSI because it will affect your choice of solar water pumps.

PSI stands for Pound per square inch. The pressure found in any enclosed system. i.e. Typically on a municipal water supply the static water pressure will be 30-60 psi.

The rated Static Pressure of our dc water pumps is the pressure the pump can handle. It is not the pressure the pump generates.

What is PSI?

What does PV mean?

Photovoltaic, (Solar Panel) a specialized semiconductor diode that converts visible light into direct current (DC). Some PV cells can also convert infrared (IR) or ultraviolet (UV) radiation into DC electricity.

Solar Panel

Solar Panel

What is PV min?

The minimum amount of Watts required to operate the pump when running directly from a PV panel.

Please remember most PV panels are not putting out their rated wattage until full sun. If you would like the pump to start running earlier in the day than full sun it would be good to utilize a larger Wattage PV Panel. While higher rated voltage than specified can affect the pump a higher wattage will not. The pump will only draw the wattage it requires.

What are WATTS?

The minimum amount of Watts required to run a solar hot water pump.

Watt is the unit of power (symbol: W). The watt unit is named after James Watt, the inventor of the steam engine. One watt is defined as the energy consumption rate of one joule per second. 1W = 1J / 1s. One watt is also defined as the current flow of one ampere with voltage of one volt.

How does the HEAD value relate to my system?

Head is the height at which water pumps can raise liquid.

*Please bear in mind that most of our customers are dealing with an enclosed solar hot water system. One where the hot water panels are on their roof. In an enclosed system, that is one completely void of air, head becomes almost a moot point. Hence, as the saying goes, what goes up must come down.

Water in a solar hot water heating system that is coming down off the roof creates a syphoning effect on the water going up to the roof, thus effectively offsetting the head pressure.

In such cases the flow rate is normally the primary concern.

Why does an AIR LOCK occur in my system?

A blockage of the flow in a pump or pipe, caused by an air bubble. An air lock is a restriction of, or complete stoppage of liquid flow. This is caused by air trapped in a high point of a liquid-filled pipe system. Air, being less dense than the liquid, rises to any high points. When pressure is applied, instead of the liquid flowing as it normally would an air lock occurs. Simply put an air bubble reduces the flow in direct proportion to the size of the air bubble. Example: a 1/4” bubble in a 1/2” line reduces the flow by 1/2.

It is common that problems with a system are due to a trapped air bubble. To fix this problem be sure to carefully purge the air from the system. See our troubleshooting video on YouTube.

What are VOLTS?

The amount of Voltage required to run a solar hot water pump.

Simply put, Volt is a unit of measuring voltage. Volt is the measure of potential difference which causes a current to flow through, having some resistance in the medium. Or in more technical terms, it is the SI unit of electromotive force, the difference of potential that would drive one ampere of current against one ohm resistance.

Water Pumps that run on PV can handle the voltage fluctuation that PV panels produce. Nonetheless, pumps are primarily designed to run on their stated voltage. For example, 12V dc water pumps should be run on a 12V PV panel and 24V dc water pumps on a 24V PV panel.

Constantly running a water pump on higher voltage will increase the speed on the pump but it will also greatly reduce their life expediency. Running the pump on a lower voltage will in turn slow the speed of the pump but will not reduce the pumps life expediency.

What is a Volt?

What are AMPS?

The minimum amperage required to operate a solar hot water pump.

Ampere or amp (symbol: A) is the unit of electrical current. The Ampere unit is named after Andre-Marie Ampere, from France. One Ampere is defined as the current that flows with electric charge of one Coulomb per second. 1 A = 1 C/s.

Volt, Amps, Watts

Do I have to always submerse a SUBMERSIBLE pump in water?

Submersible pumps operate in or out of water. Their waterproof housing allows them to be submersed without causing damage.

Important. Please note that dc water pumps marked as H (for high temperature rating) cannot be submersed in high temperature liquid. You must either use the pump as an external high temperature pump or a submersed low temperature pump.

What is the difference between WATTS AND AMPS?

There is a big difference between the two though as watts is a comprehensive measurement of power while amps is just the quantity of current being drawn. The amount of power can still vary depending on the voltage. The current in amps and the voltage of the source multiplied is equal to the power draw in watts.

What is the difference between VOLTS and WATTS?

One of the major difference between volts and watts is that the volt is the SI unit of potential difference and electromotive force, whereas the watt measures the SI unit of power. … The measurement taken in volts is easier as compared to watts because watts is the product of the two quantity i.e., voltage and current.

Watts and Volts