These two hot water recirculation systems are my favorites. Here is a quick comparison between the two models.
Watts 500800
Grundfos 595916
Timer, Fittings, Check Valve ✓
Timer, Fittings, Check Valve ✓
1-Year Limited Warranty
Water Heater Installed System
Weight: 8 lbs.
Amazon 4.5/5 Stars (550+ Reviews)
2- Year Warranty From the Date of Installation
Water Heater Installed System
Weight: 6 lbs.
Amazon 4.5/5 Stars (200+ Reviews)
-Summary-
The difference boils down to this: With the Grundfos model, you get an extra year of warranty for $40 more.