Boiler pump questions

[MAD-DIYer]

Thanks for having me. New to radiant system as I’m from a forced air background. House has a gas boiler that works well thus far. Examining the setup I see two pumps, the grey unit appears to be the active pump when it kicks in. I’m not sure the role of the red unit.

My goal is to replace the pump with an super energy efficient model. But I’ll most likely do this come spring. Any help would be greatly appreciated.

 

[ShaunCorbs]

Hot water storage ? And tbh I would keep the old ones until they break wouldn’t upgrade you won’t get much payback

As the red one isn’t even an amp