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View Full Version : UPS backup for SDHW pumps


Shawn Brown
28th September 2009, 19:15
I recently purchased a UPS backup for my sdhw system. When I tested it the pumps (Wilo and Grundfos) made a rather unhealthy sounding noise. The output from the UPS is a stepped sine wave. The unit is an APC rated for 1300va or 780w.

Do I need something closer to a sine wave output? Will the pumps be damaged?

Shawn.