Hot water circulation, what is this pump doing?

[Rapidrob]

I replaced a friends water heater yesterday and noticed that on the waters drain / flush connection on the bottom there is a water line going from the drain valve manifold to a strainer and then to a 120 VAC circulation pump and then back into the homes hot water system. No idea what this is used for?
Is it to prevent sediment from building up? The other side of the manifold has a flush ball valve and a hose to a floor drain making it very handy to flush out the water heater.

 

[hj]

Hot water circulation system to give "quick" hot water to the faucets.

 

[Sponsor]

 

[Rapidrob]

Hot water circulation system to give "quick" hot water to the faucets.

Thank you. That makes sense.