Watts Tekmar 256 Installation & Operation Manual Download Page 17

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The minimum temperature allowed for the boiler

target temperature.

OFF, 80 to 180°F

(OFF, 27 to 82°C)

The differential that the control is to use when it is

operating the boiler.

Ad, 2 to 42°F

(Ad, -17 to 6°C)

The system’s warm weather shut down during the

occupied (Day) period.

35 to 100°F, OFF

(2 to 38°F, OFF)

The system’s warm weather shut down during the

unoccupied (Night) period.

35 to 100°F, OFF

(2 to 38°C, OFF)

The units of measure that all of the temperatures

are to be displayed in the control.

°F, °C

This item exits the ADJUST menu by pressing

either the or button.

Section

Adv

anced

Ins

taller

Display

Description

Range

Actual

Setting

Adjust

Menu (2 of 2)

17 of 20

ADJUST

BOIL

MIN

ADJUST

DIFF

BOIL

ADJUST

WWSD

OCC

ADJUST

WWSD

OCC

ADJUST

Summary of Contents for Tekmar 256

Page 1: ... Input 24 V ac Power Supply Output Boiler Input tekmar Timer Optional BOIL F OCC Input Boiler Demand Signal PRGM S TIME AMPM UNOCC OVR S M W T F T 1 2 Press Release all 3 buttons to adjust menu Press Hold Item to view settings to test Boiler Control 256 One Stage Boiler Item Date Code Power 24 V 10 50 60 Hz 3 VA Class 2 Relay 240 V ac 5 A 1 6 hp Meets Class B Canadian ICES FCC Part 15 H1190D Termi...

Page 2: ...yed in the item field of the display To view the next available item press and release the Item button Once you have reached the last available item pressing and releasing the Item button will return the display to the first item Adjust To make an adjustment to a setting in the control press and hold simultaneously for 1 second all 3 buttons The display will then show the word ADJUST in the top ri...

Page 3: ... the selected item Terminal Unit TARGET INDR DSGN DIFF BOIL OUTDR ROOM WWSD F C MAX MIN OCC UN VIEW ADJUST Boiler Demand Burner Displays when the boiler relay is turned on F C F C Displays the unit of measure that all of the temperatures are to be displayed in the control OCC Occupied Schedule Displays when the control is in occupied Day mode UNOCC Unoccupied Schedule Displays when the control is ...

Page 4: ...rted together the control operates in the unoccupied Night mode When in the unoccupied Night mode the UNOCC segment is displayed in the LCD The 256 adjusts the supply water temperature based on the UNOCC settings made in the control FACTORY DEFAULTS The control comes preset with several factory defaults These defaults are based on the terminal unit selection see section B2 To fine tune building re...

Page 5: ...l unit is used the control varies the supply water temperature according to the type of terminal unit This improves the control of the air temperature in the building BOILER TARGET TEMPERATURE BOIL TARGET The BOIL TARGET temperature is determined from the Characterized Heating Curve settings and the outdoor air temperature The control displays the temperature that it is currently trying to maintai...

Page 6: ...r a thick concrete or gypsum pour This heating system has a large thermal mass and is slow acting Default values BOIL DSGN 120 F 49 C BOIL MIN OFF Low Mass Radiant 2 This type of radiant heating system is either attached to the bottom of a wood sub floor suspended in the joist space or sandwiched between the sub floor and the surface This type of radiant system has a relatively low thermal mass an...

Page 7: ...he BOIL TARGET temperature The boiler maximum is the BOIL DSGN plus 10 F 5 C but limited to 225 F 107 C If the control does target the boiler maximum and the BOIL temperature is near the boiler maximum temperature the MAX segment will be displayed in the LCD while either the BOIL TARGET temperature or the BOIL temperature is being viewed At no time does the control operate the boiler above 248 F 1...

Page 8: ...ever the control does not operate the heating system to satisfy this demand CAUTION Improper installation and operation of this control could result in damage to the equipment and possibly even personal injury It is your responsibility to ensure that this control is safely installed according to all applicable codes and standards This electronic control is not intended for use as a primary limit c...

Page 9: ...it snaps into place STEP TWO CONTROL INSTALLATION STEP THREE SENSOR INSTALLATION Caution Do not run sensor wires parallel to telephone or power cables If the sensor wires are located in an area with strong sources of electromagnetic interference shielded cable or twisted pair should be used or the wires can be run in a grounded metal conduit If using shielded cable the shield wire should be connec...

Page 10: ...resents the heat load on the building a northern wall for most buildings The 070 should not be exposed to heat sources such as ventilation or window openings The 070 should be installed at an elevation above the ground that will prevent accidental damage or tampering Connect 18 AWG or similar wire to the two terminals provided in the enclosure run the wires from the sensor to the control Do not ru...

Page 11: ... steel black iron pipe is used In general it is recommended that a temperature well be used for steel pipe of diameter greater than 1 1 4 32 mm Temperature wells are also recommended when large diameter pipes are used and fluid stratification is present Conduit Connection The Universal Sensor and Universal Sensor Enclosure 080 sold separately are specifically designed to mount onto a 3 8 10 mm ID ...

Page 12: ...80 50 10 19 900 120 49 3 760 190 88 983 15 26 139 403 55 13 17 436 125 52 3 383 195 91 903 10 23 118 018 60 16 15 311 130 54 3 050 200 93 829 5 21 100 221 65 18 13 474 135 57 2 754 205 96 763 0 18 85 362 70 21 11 883 140 60 2 490 210 99 703 5 15 72 918 75 24 10 501 145 63 2 255 215 102 648 10 12 62 465 80 27 9 299 150 66 2 045 220 104 598 15 9 53 658 85 29 8 250 155 68 1 857 225 107 553 A good qua...

Page 13: ...etween 21 and 27 V ac when the boiler demand device calls for heat Test The Outputs Boiler Make sure power to the boiler circuit is off and short the boiler wires When the boiler circuit is powered up the boiler should fire If the boiler does not turn on refer to any installation or troubleshooting information supplied with the boiler The boiler may have a flow switch that prevents firing until th...

Page 14: ...d Input Connections Do not apply power to these terminals as this will damage the control Outdoor Sensor Connect the two wires from the Outdoor Sensor to the Out and Com terminals 2 and 3 The outdoor sensor is used by the 256 to measure the outdoor air temperature Universal Sensor Connect the two wires from the Universal Sensor to the Boil and Com terminals 1 and 3 This sensor is used by the 256 t...

Page 15: ...n to set the desired temperature The ROOM UNOCC setting is set to the desired room air temperature during the unoccupied Night mode Note To increase or decrease space temperature during the unoccupied Night mode only adjust the ROOM UNOCC setting This is only used if a tekmar timer is installed Press and release the Item button to advance to the OUTDR DSGN adjustment Use the or button to set the o...

Page 16: ...outdoor air temperature used in the heat loss calculation for the heating system 60 to 32 F 51 to 0 C B2 The type of terminal units that are being used in the heating system B2 S e c t i o n A d v a n c e d I n s t a l l e r Display Description Range Actual Setting The design indoor air temperature used in the heat loss calculation for the heating system 35 to 100 F 2 to 38 C B3 The design supply ...

Page 17: ...F OFF B3 The system s warm weather shut down during the unoccupied Night period 35 to 100 F OFF 2 to 38 C OFF The units of measure that all of the temperatures are to be displayed in the control F C This item exits the ADJUST menu by pressing either the or button S e c t i o n A d v a n c e d I n s t a l l e r Display Description Range Actual Setting B3 Adjust Menu 2 of 2 2019 tekmar 256_D 09 19 1...

Page 18: ...hours of time in troubleshooting a system Note flow directions in the system paying close attention to the location of pumps check valves pressure bypass valves and mixing valves Ensure correct flow direction on all pumps This is also a very useful step if additional assistance is required Document the control for future reference Before making any adjustments to the control note down all of the i...

Page 19: ...act will operate for up to 10 minutes of a 20 minute cycle Locate and repair the problem as described in the Testing section To clear the error message from the control after the sensor has been repaired press the Item button The control is no longer able to read the boiler sensor due to an open circuit In this case if the BOIL MIN adjustment is set to OFF the control does not operate the Boiler c...

Page 20: ... original cost of the defective product and such repair exchange or credit shall be the sole remedy available from tekmar and without limiting the foregoing in any way tekmar is not responsible in contract tort or strict prod uct liability for any other losses costs expenses inconveniences or damages whether direct indirect special secondary incidental or consequential arising from ownership or us...

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