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2013 Solar Products Catalog
Specializing in Sustainable Solar and Wind Energy Products to Brighten your Life!

  

Circulating Pumps

 
 
Pumps used in solar heating systems are called hot water circulator pumps. Many pumps are not designed for more than 120°F and will fail prematurely if used in heating systems. Solar heating pumps are sized to the application based upon head and flow rate. The head of a pump is the power it has to overcome both the vertical height that the liquid must be pumped and the friction of the liquid against pipe walls.  Frictional head loss is not significant except in very large piping systems. Hot water circulators are designed with a wide range of head and are classified as low head (3' to 10'), medium head (10' to 20') and high head (more than 20'). Low and medium head pumps are normally used for closed loop (glycol and DHW) systems. High head pumps are used for drainback systems and large baseboard or radiant floor heating systems.

Pumps for domestic hot water or other open loop systems should have bronze or stainless steel housings to prevent scale from building up. Pumps for closed loop systems may have iron housings although a bronze or stainless steel housing will normally last longer.


Pumps and Flow Rate
If the system controls are working correctly, an inoperative pump may be due to a stuck impeller, a burned-out motor, or a broken shaft.  These types of problems may be expected over the lifetime of any component subjected to the temperature and cycling stresses of a solar system pump. Even though a solar pump is operating and is being controlled correctly, there still may be problems with the actual flow rate in the collector loop. If the pump has been sized to just barely overcome the pressure head of the collector loop, an unexpected added resistance can stop all flow through the collector. For example, air in the fluid may, over a period of time, collect in a section of piping, especially if it cannot escape through a vent to the atmosphere. This "air lock" can prevent any flow if the pump does not have the capacity to compress the air completely and force it through the system. In an indirect system, loss of collector fluid pressure can also prevent flow in the collector loop. The pump is generally not sized to overcome the static head or pressure due to the difference in height between the top and bottom of the collector loop. It is usually sized to maintain the desired flow against the dynamic head or pressure due to the resistance to flow in the pipes, fittings, and valves. If the fluid pressure to overcome the static head is lost, then the pump may not be able to maintain flow against the combined static and dynamic head of the system.
 

DC CIRCULATOR PUMPS
 
EL-SID Busrhless Water Circulators

These tiny brushless, magnetic drive circulators can be driven by PV modules or 12 volt batteries for closed-loop circulation in solar water heating systems, individual space heat zones and individual loop radiant floor loops. Use of several small pumps in a radiant floor system allows each loop to be controlled by a different thermostat.

Model SID10 is designed to be powered by a 10 watt PV module, in open loop systems and can pump 3.3 gallons per minute at no head and ˝ GPM at 2.5 feet of head at 17 volts input.

A 20 watt module should be used for glycol systems. It can circulate water in a well designed solar water heating system with two 4 x 10 collectors. Model SID10B is designed to be battery powered and has the same specifications at 12 volts.

Dimensions: 4" x 4" x 5".

Spec Sheet

Model Number

Flow (GPM) at No Head

Volts (Max)

Head (ft)

Weight (lbs.)

PART NUMBER

OUR PRICE

Purchase

EL-SID 10P-12

3.3

20

3.5

2

075-07218

$298

EL-SID 10B-12

3.3

17

3.5

2

075-07219

$298

EL-SID 10B-24

5.0

32

6.5

2

075-07222

$361

EL-SID 20P-12

5.0

20

6.5

2

075-07226

$336

EL-SID 20B-12

3.3

17

3.5

2

075-07224

$398

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This page designed and maintained by Terry R. Wolff Last up-dated on February 27, 2015
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