For several years, we carried the Grundfos SBA 3-45-AW automatic cistern pump. We've used many different pumps made by Grundfos over the years, and they are known to make quality, innovative products, so we jumped at the opportunity to carry an easy-to-install, pressure-tank-free alternative to traditional pumping systems. However, we recently became troubled by the number of failures that were being reported from the SBA model, and have since decided to stop selling these units.
Automatic cistern pumps (i.e., pumps that do not require an external pressure switch to operate, or a large pressure tank) certainly have their place: We get thousands of requests per year from homeowners who are building cabins or have limited utility space and just can't spare 4-6 sq. ft. of floor space for a pressure tank. Also, when using a rain cistern or spring tank for irrigation, automatic pumps cut out the need for pump start relays.
In our experience, though, the Grundfos SBA is too much of a gamble in the realm of automatic pumps. While Grundfos has done a great job honoring warranties, the number of warranty claims that we submitted on the SBA model far exceeds any other product that we've ever carried. In fact, if we get more than a 3% failure rate within warranty periods, we will drop a product. Because the SBA was new to the US market as of a couple years ago, we decided to trust the Grundfos brand since they are an international company that has been making pumps for 50+ years. However, after about 18-22 months of use, we were seeing far too many pump failures. Additionally, in the last month, we had as much as 30% of these SBA pumps be defective right out of the box.
Mistakes in manufacturing happen. We get that. But, to add insult to injury, the staff of Grundfos has left us completely in the dark on why these failures were occurring, what was causing them, and what (if anything) they were doing to address and remedy these issues.
On the flip side, we have been carrying another brand of automatic cistern pump -- the Strom BSP -- for nearly as long as we've carried the Grundfos SBAs, and have seen less than 0.5% failure rate. As a result, we are urging customers who really need that automatic cistern pump for their application to consider the Strom BSP. Please note, though, that we almost exclusively recommend that customers go with the 3/4HP model... not the 1HP. The 3/4HP Strom BSP is ideal for residential water supply to a house/barn/etc. Customers should only use the 1HP model if they are planning on running irrigation systems with the pump with flow rates of over 15GPM @ 50PSI, or if you pumping uphill more than 80 ft. Also, it is recommended that a 2-gallon pressure tank be installed with the Strom BSP somewhere in your plumbing supply (ideally either in the cistern or immediately where the water supply line enters the house/structure from the cistern).
The Strom BSP comes with built-in run-dry protection, and an optional floating intake sleeve is available for the unit.