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  Tekmar Universal Reset Module - Four tN4, Two Boiler, DHW & SP
Tekmar Universal Reset Module - Four tN4, Two Boiler, DHW & SP
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Tekmar Universal Reset Module - Four tN4, Two Boiler, DHW & SP

The Universal Reset Module 423 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 baseboard with an on/off boiler, to four temperature systems comprised of multiple fan coils, baseboard, mixed radiant floor zones, and two modulating/condensing boilers. This control regulates up to four space heating water temperatures through Outdoor Temperature Reset and Indoor Temperature Feedback. It is capable of controlling two on/off or modulating boilers, Domestic Hot Water, setpoint loads, and can expand up to 24 zones for each space heating water temperature (96 in total).


  • Automatic Boiler Differential
  • Boiler Protection
  • Controls up to 4 water temperatures (with use of up to 3 mix expansion modules)
  • DHW Post Purge
  • DHW Priority (optional)
  • DHW control
  • Exercising
  • Expandable up to 96 zones
  • Indoor Temperature Feedback
  • One touch overrides (with optional User Switch)
  • Outdoor Temperature Reset
  • Powered pump outputs
  • Setpoint operation
  • System Setback (with optional Timer)
  • Two on/off or two modulating boiler control
  • Warm Weather Shut Down
  • Zone Synchronization


Control Microprocessor PID control; This is not a safety (limit) control
Packaged weight 1.83 lb. (830 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, CSA/UL 61010-1, 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% from 104 to 122°F (40 to 50°C), Altitude <6560 feet (2000 m), Installation Category II, Pollution
Power supply Provided by interconnected tekmarNet Zone Manager
Pump relays 115 V (ac) 5 A, 1/6 hp
Combined load 10 A Maximum (for DHW and Primary Pump)
DHW valve output 24 V (ac) 8 VA Maximum
Modulation output 0-10 V (dc) Minimum 2500
Boiler relay 115 V (ac) 5 A
Demands 20-260 V (ac) / 0.1 VA @ 24 V
Sensors NTC thermistor, 10 k @ 77°F (25°C ± 0.2°C) ß = 3892
-Included Outdoor Sensor 070 and Universal Sensor 082
-Optional tekmar type#: 078
Warranty Limited 3 Year Warranty

Current Literature

Product Submittal

Jan 2011 - Present


Installation & Operation Manual

Aug 2007 - Present


Job Record

Aug 2009 - Present


Wiring Brochure

Mar 2009 - Present


Installing tN4 Reset Modules 420, 422 and 423 with Modulating Boilers

Mar 2011 - Present


RF Noise Interference

May 2009 - Present


Part Number: 423

2 +$731.96

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