The Mixing Reset Module 421 is designed to operate all of the mechanical equipment in a hydronic heating system, except for zones, coordinating their operation through network communication. It can be used in applications ranging from a single zone of mixed radiant with an on/off boiler to multiple radiant floor zones with an on/off boiler. This control regulates one mixed heating water temperature through Outdoor Temperature Reset and Indoor Temperature Feedback. It is capable of controlling a single on/off boiler, floating action or variable speed injection mixing, and can expand up to 24 zones in total.
Features
Automatic Boiler Differential
Boiler Protection
Exercising
Expandable up to 24 zones
Indoor Temperature Feedback
One touch overrides (with optional User Switch)
Outdoor Temperature Reset
Powered pump outputs
Single on /off boiler control
System setback (with optional timer)
Variable speed, or floating action mixing control
Warm Weather Shut Down
Zone Synchronization
Specifications
Control
Microprocessor control. This is not a safety (limit) control
Packaged weight
1.6 lb (730 g)
Dimensions
3-5/8" H x 5-3/8" W x 9/16" D (92 x 137 x 14 mm)
Approvals
CSA C US, meets Class B: ICES & FCC Part 15
Ambient conditions
Indoor use only, 32 to 122°F (0 to 50°C), RH ≤80% to 88°F (31°C), down to 50% above 104°F (40°C), Altitude <6560 ft. (2000 m), Installation Category II, Pollution Degree
Product Submittal 
