Caution: Improper installation and operation of this control could result in damage to 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.
Step One
Getting ready
Check the contents of this package. If any of the contents listed are missing or damaged, please refer to the Limited Warranty and
Product Return Procedure on the back of this brochure and contact your Wholesaler or tekmar Sales Agent for assistance.
Type 258 includes:
• One Control 258 • One Outdoor Sensor 070 • One Universal Sensor 071
• One Universal Sensor Enclosure 080 • One Data Brochure D 258 • One Data Brochure D 001
• One Application Brochure A 258
Other information available:
• Essay E 001 • Essay E 002
Read Application Brochure A 258 and select the correct Application for your job.
Note: Carefully read the details of the Application, and the Sequence of Operation sections in all applicable brochures to ensure that
you have chosen the proper control, and you understand its functions within the operational requirements of your system.
Step Two
Mounting the base
The control should be removed from its base by pressing down on the release clip in the wiring chamber and sliding upwards on the
control. The base is then mounted in accordance with the instructions in the Data Brochure D 001.
Step Three
Rough-in Wiring
All electrical wiring terminates in the control base wiring chamber. It has standard 7/8" (22mm) knock-outs that will accept common
wiring hardware and conduit fittings. Before breaking out the knock-outs, check the wiring diagram and select those sections of the
chamber with common voltages, since the safety dividers will later prevent wiring from crossing between sections. Standard 18 to
22AWG solid wire is recommended for all low voltage wiring to tekmar controls. Heavier guage wire may not fit properly into the
terminal plugs, while lighter guage wire is too fragile and may also contribute too much resistance to the circuit.
Power should not be applied to any of the wires, during this rough-in wiring stage.
Step Four
Electrical connection to the control
Power and output connections
The installer should test to confirm that no voltage is present at any of the wires.
Install the control into the base, sliding it down until it snaps into place.
All electrical connections are made directly to the terminal plugs.
Connect the 24Vac power supply from the secondary side of a 24Vac Class II transformer to
terminals
Power C — R (1 and 2). Do not connect either of the transformer terminals to ground.
Connect the system pump circuit to terminals
System Pmp (3 and 4). These terminals lead to a 10 amp
dry relay contact which closes when the control requires system pump operation.
Note: The 258 is approved for low voltage only (Maximum 24Vac). The system pump must be switched
through an isolation relay approved for the line voltages required to operate the pump.
7
Installation
Maximum 24 Volts
Connect the combustion air damper circuit to terminals
Comb. air (7 and 8). These
terminals lead to a 10 amp dry relay contact which closes when the control requires
combustion air damper operation.
Note: The 258 is approved for low voltage only (Maximum 24Vac). If the combustion air
damper operates on line voltage, it must be switched through an isolation relay.
6
7
8
5
Dem
9
10
11
12
13
Stage
1
2
3
Stage
2
1
Dem
Comb.
Air
Heat
1
2
3
4
C
R
Power
Pmp Pmp
System
• Install the Outdoor Sensor 070, and the Universal Sensor 071 according to the instructions in the Data Brochure D 001 and run the
wiring back to the control.
Option: A 10K tekmar Zone Control can also be connected (purchased separately).
• Install the wiring from other system components; Boiler(s), Pump relay, Heat Demand
or Setpoint Demand circuits to the base.
• Install a 24Vac Class II transformer with a minimum 5VA rating close to the control, and run the wiring from the transformer to the
base.
A Class II transformer must be used. Do not connect any of the transformer terminals to ground
.
1
2
3
4
C
R
Power
Pmp Pmp
System
