Tekmar 421 Data Brochure
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Tekmar 421 Data Brochure

Tekmar 421 Data Brochure

Mixing reset module
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- Data Brochure
Mixing Reset Module 421
1
2
Information
Application
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Brochure
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to match
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application
applications
Introduction
The Mixing Reset Module 421 provides outdoor reset to a hydronic heating system in order to maximize comfort and
efficiency. The 421 can operate a single on / off boiler and a single mix water temperature. The mix output can operate a
floating action mixing valve or a variable speed injection pump.
Features:
• tN4 Compatible
•
• • Outdoor Reset
• • Single On-Off Boiler
• • Powered Pump Outputs
Boiler
51 52
/
Boil Sens Sup / Ret
Off / Flushing
Meets Class B: Canadian
ICES & FCC Part 15
Made in Canada
Test
Var. Pump Fuse
T2.5 A 250 V
3
4
Rough-in
Wiring
Rough-in
wiring
instructions
Floating Output:
24 V (ac) 8 VA
Menu
Item
61
62
2.5 A
Variable Speed
Pump
N
1 of 20
5
Wiring
Data
Brochure
Brochure
Wiring and
Control settings
installation of
and sequence of
specific control
operation
• • Variable Speed Injection Pump
• • Floating Action Valve
• • Includes Sensors
C
Opn
Cls
R
R
53
54
55
Powered Output
Mixing Reset Module 421
D 421
08/07
6
Job
Record
Record settings &
wiring details for
future reference
Com Boil Mix
Com Out
56
57
58
59
60
Do not apply power
tN4
tektra 991-02
Var. Pump: 115V (ac) 2.5 A
Relay Rating: 115V (ac) 5 A
7.5 A
63
64
max
System P1
Pump
N
© 2007
D 421 - 08/07

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Summary of Contents for Tekmar 421

  • Page 1 The Mixing Reset Module 421 provides outdoor reset to a hydronic heating system in order to maximize comfort and efficiency. The 421 can operate a single on / off boiler and a single mix water temperature. The mix output can operate a floating action mixing valve or a variable speed injection pump.

  • Page 2: Table Of Contents

    Use the Lock / Unlock DIP switch to lock and unlock the Access Powered Output Do not apply power Mixing Reset Module 421 Level of the 421 and all connected tN4 devices, including Menu tN4 thermostats. For details, see “Access Levels” Item...

  • Page 3: Access Level

    Maximum setting. system pumps are turned on for 4 minutes. • • If the 421 provides a heat demand to an external boiler • • To activate the Flushing feature, set to Flushing. control, this DIP switch must be set to Ret. Install the •...

  • Page 4: Display And Symbols Description

    OPEN / CLOSE WARNING Displays whether the actuator is opening or Displays when an error exists. closing the mixing valve. COMMUNICATION BUS Displays when tN4 thermostats are connected. © 2007 D 421 - 08/07 4 of 20...

  • Page 5: User Interface

    Item, Up, Down) to select settings. As you enter settings, 1. Select the appropriate menu using the Menu button. record the settings in the Job Record J 421. 2. Select the item using the Item button. 3. Use the Up or Down button to make the adjustment.

  • Page 6: Display Menus

    Note: This item is only available when the Boiler Sensor Sup / Ret DIP switch is set to Sup. After the last item, the control returns to the first item in the menu. © 2007 D 421 - 08/07 6 of 20...

  • Page 7: Adjust Menu

    The minimum allowed mix target temperature. Default = OFF 80 to 220°F, OFF (26.5 to 104.5°C, OFF) MIX MAXIMUM SECTION C The maximum allowed mix target temperature. Default = 140°F (60.0°C) Continued on next page. 7 of 20 © 2007 D 421 - 08/07...
  • Page 8 Default = 60°F (15.5°C) Note: This item is only available when the Schedule is not set to OFF. After the last item, the control returns to the first item in the menu. © 2007 D 421 - 08/07 8 of 20...

  • Page 9: Miscellaneous Menu

    • • If the test sequence is paused for more than five minutes, the control exits the entire test routine. • • To advance to a particular step, repeatedly press and release the Test button to display the appropriate device. 9 of 20 © 2007 D 421 - 08/07...
  • Page 10 If a device fails to operate during the test sequence, refer to the HAZARD W 421 Wiring Brochure to check the operation of the control. Access to the Test button requires the removal of the If the control works properly, refer to any troubleshooting front cover and exposes hazardous voltage while the information supplied by the equipment manufacturer.

  • Page 11: Sequence Of Operation

    Outdoor Reset Module (thermostats, Reset Module and Expansion Modules). Each The Mixing Reset Module 421 is the system control for a tN4 device is connected to a tN4 communication bus using hydronic heating system. The 421 operates a single heat two wires.
  • Page 12 The WWSD setting is found in the Adjust menu. element to deliver heated air into the space. The amount of natural convection is dependant on the supply water temperature to the heating element and the room air temperature. © 2007 D 421 - 08/07 12 of 20...

  • Page 13: Mixing Operation

    4-way valve. A visual indication as to whether the control is The Mix outputs are built-in to the 421. The type of mixing currently opening or closing the mixing valve is displayed device is selected using the Mix Mode setting. The mixing...

  • Page 14: Boiler Temperature Control

    An on / off heat source must be operated with a differential 421’s boiler sensor DIP switch is set to Supply. The boiler in order to prevent short cycling. With the control, either target temperature is determined using Boiler Load Reset, a fixed or an auto differential may be selected.

  • Page 15: Boiler Enable

    Boiler Enable Section E If the 421 is one of many controls that can call for heat to When the boiler sensor is located on the boiler return, the a single boiler or there is a boiler sequencer other than a...

  • Page 16: Error Messages

    Device is attempting to Keep pressing the Item Once error is corrected, show supply temperature button to find the actual the temperature can be but cannot because of error message displayed sensor problem. © 2007 D 421 - 08/07 16 of 20...
  • Page 17 The control will not operate the boiler contact if the Boil Minimum setting is less than 100°F (38.0°C). Locate and repair the problem as described in the Data Brochure D 070. 17 of 20 © 2007 D 421 - 08/07...
  • Page 18 #:## is the address of the device with the error. The bus number displays before the colon, and the device number displays after. Go to the device with the address displayed. Possible Addresses: 1:01 to 1:24 - Device Error on Bus 1 © 2007 D 421 - 08/07 18 of 20...

  • Page 19: Troubleshooting

    Replace fuse. Check breaker panel or disconnect. Check No voltage to control. voltage using a voltmeter. Plugs are not connected between the 421 Ensure the plugs are secured to the Zone Display is not on. to the Zone Manager. Manager pins.

  • Page 20: Warranty

    Purchaser shall indem- such Product sale and acknowledges that it has read nify and hold tekmar harmless from and against any and all and understands same. claims, liabilities and damages of any kind or nature which...

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