The pump is currently being tested and used on a small hot water drain back solar system. The system is open to the atmosphere at the water storage tank point. The pump is positioned at the lowest point of the water system next to a 25 gallon uncovered storage tank. To date, the pump has less than 60 hours of operating time and has experienced water temperatures not exceeding 120 degrees Fahrenheit.

The vertical distance from the pump's output to the highest plumbing point of the collectors is approximately 22 feet. All piping is constructed of 3/4 inch copper to and from and within the collectors. The system is completely fresh potable water. No chemicals or antifreeze solutions are used. Currently, two homemade collectors are being used which measure nominally 2ft width by 8ft length. Therefore, each collector has a surface area of 16 square feet. Within each collector is approximately 70 linear feet of 3/4 copper piping soldered in close serpentine turns using 90 degree street elbows.

Under these operating conditions the 009B pump has operated well. While the pump is running the collectors are well flushed with water as indicated by temperature measurements using type K thermocouple sensors which are mounted within the collectors. Using a manual valve the water flow per gallon through the collectors is throttled back to something less than 3 gallons per minute. However, the actual water flow at this time is only estimated. Therefore, the pump has more than sufficient pumping capacity to adequately supply water to this size solar collector system. It is planned in the future to add more collectors of this description to the system.

Electrical measurements of the 009B pump indicate that the amperage draw is about 1.2 amperes while the pump is operating continuous. Initial start spike current would probably be at least three times that amperage amount.
Therefore, the electrical relay starting circuitry would be well within the light duty range of less than a 10 ampere contact rating. In terms of overall energy gain and efficiency the watt energy used by the pump of course would need to be deducted from the overall solar BTU energy gain of the system. Thus far, this small pilot solar system has ran mostly under conditions where the ambient temperatures were below the sub-freezing range. On some days the ambient temperatures were in the single digits Fahrenheit and the system still realized accumulated water tank storage temperatures of 80 to 100 degrees Fahrenheit.

Due to the close spaced serpentine turns of the copper pipes within the collectors an air injection method was developed with this system to purge any accumulated water which may still be in the piping after the pump was shut down and allowed to drain. The concern was that enough residual water could possibly pool within the pipes to pose a water freezing problem later. Therefore, a single shot of 120 psi of compressed air is blown through the collector system after the system has drained. Even with the piping within the collectors sloped as much as practical it was surprising to see the amount of water which was still flushed from the system. It was found that the 009B pump is quite sensitive to losing it's prime if this purging air was allowed to flow back through the water pump. Therefore, the pump was valved isolated while the system was air purged.

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