VFD drive for a pond pump?

[MuzzerParticipant @muzzer]

These are typical CH pump characteristics. They really don't care if they are fully blocked or totally unloaded. They're pretty good as coolant pumps and will generate a decent head of 5m or so, which is good for many applications, assuming the impeller is submerged at startup. And they cost peanuts, esp if you have an old CH pump to hand..

Obviously when the pump is generating its maximum head (and zero flow), it is putting a (relatively) large torque on the motor, so takes a fair bit of power. This will end up as heat but it's not enough to be a problem.

In terms of useful work done, the calculation is pressure x flow rate. These things are fairly inefficient but we're talking about very modest power levels.

Grundfos site link.

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