Submittal Sheet

Job __________________________
Designer ______________________
Contact _______________________
www.tekmarcontrols.com  of 2 © 20 C 256 - 0/
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0/
HVAC Systems Replaces: New
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Outdoor Temperature Reset
Setback input for night setback
Warm Weather Shut Down
Automatic Boiler Differential
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Quick setup for easy installation and
programming
Advanced settings to fine-tune building
requirements
Test sequence
CSA C US certified (approved to applicable
UL standards)
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 -----------------------------------------------------
The Boiler Control 256 is designed to operate a single boiler using outdoor reset. It can be used in applications ranging from a single
zone of baseboard to multiple zones of fan coils and baseboard. This control regulates a single heating water temperature through
outdoor reset. It is capable of controlling a single on/off boiler.

N / A
One Stage Boiler
Literature D256, A256, D00, D070
Control Microprocessor control. This is not a safety (limit) control
Packaged weight .3 lb. (580 g)
Dimensions 4-3/4” H x 2-7/8” W x 7/8” D (20 x 74 x 22 mm)
Enclosure White PVC plastic, Nema Type 
Approvals CSA C US, meets class B: ICES & FCC Part 5
Ambient conditions
Indoor use only, 32 to 04°F (0 to 40°C), RH ≤90% Non-
condensing
Power supply 24 V ±0%, 50/60 Hz, 3 VA, Class 2
Relay 240 V (ac) 5 A /6 hp
Demand 24 V (ac) 2 VA
Sensors NTC thermistor, 0 kΩ @ 77°F (25°C ±0.2°C) ß=3892
–Included Outdoor Sensor 070 and Universal Sensor 07
–Optional tekmar type #: 033
Warranty Limited 3 Year (See D256 for full warranty)
Front View
BOIL
F
OCC
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
Terminal Unit Boiler Demand
Made in Canada
Signal wiring
must be rated
at least 300V
Inst / Adv
1
Boil
2
Out
3
Com
4
UnO
Sw
5
Boiler
6 7
T
8
Power
R+
9
C-
Do not apply power
tektra 909-01
2–7/8”
(74 mm)
4–3/4”
(120 mm)
Side View
7/8”
(22 mm)
Cover O
Item
1–3/8”
(37 mm)
6/8”
(18 mm)
6/8”
(18 mm)
BOIL
F
OCC
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
H90D
Terminal Unit Boiler Demand
Made in Canada
Signal wiring
must be rated
at least 300V
Inst / Adv

Boil
2
Out
3
Com
4
UnO
Sw
5
Boiler
6 7
T
8
Power
R+
9
C-
Do not apply power
tektra 909-01