Did you change the pump with exactly the same model, or is it a higher GPM pump?Also sounds like your zone valves are shutting off too fast, before the pump slows. What is the make/model?A water-bound expansion tank could also cause this problem. What type do you have-j--if it aint broke, tweak it!!currently on FiOS (kick aZZ!)
The pump is identical. Taco 007-F5.I'll check the zone valves tomorrow, but they're Honeywell and are motor actuated, spring return.Expansion tank seems ok. It's a ~2 gallon bladder tank. Tapping on the air side sounds hollow, tapping the water side sounds full.