Tjernlund 950-0484 Mac-3 (Discontinued - No longer available) Board Kit 8505009 Rev. 08/00 - Manual (Page 3)

CAUTIONS
1. Failure to install, maintain and/or operate the MAC-3 in accordance with manufacturer’s instructions may result in conditions that
can produce bodily injury and property damage.
2. The safety interlock and system operation performance checks must be performed on each appliance interlocked with the
MAC-3 in accordance with the Power Venter, Draft Inducer, IN-FORCER or Damper installation instructions.
ELECTRICAL
All wiring from the MAC-3 to the appliance must be appropriate Class 1 wiring as follows: installed in rigid metal conduit, intermediate conduit,
rigid non-metallic conduit, electrical metallic tubing, Type MI Cable, Type MC Cable or be otherwise suitably protected from physical damage.
The disconnect means and circuit protection are to be provided by the installer of this device.
SEQUENCE OF OPERATION OF MAC-3 INTERLOCKED WITH 24 VAC & 115 VAC APPLIANCE CONTROL CIRCUITS
The circuit board of the MAC-3 is designed for a simple three wire interlock with up to three separate burners. Upon a call for heat the “hot”
leg of the burner circuit is intercepted and routed to the MAC-3 terminal strip. The MAC-3 is activated, the power venter, draft inducer,
IN-FORCER or damper starts. The proving switch makes and the intercepted “hot” leg is returned to the burner circuit, allowing the burner to
fire. Plug-in relays must be purchased separately depending on control system voltage of appliance.
Use Tjernlund part # 950-1040 relay For 24 VAC control systems
Use Tjernlund part # 950-0480 relay For 115 VAC control systems
1
ELECTRICAL SPECIFICATIONS TABLE
Optional Limit (Spill Switch)
Used in conjunction with Optional Alarm
Sequencer
115 VAC Proven “HOT” From Fan Prover
115 VAC Neutral To Inducer / Venter / IN-FORCER
115 VAC “HOT” To Inducer / Venter
/ IN-FORCER motor & Fan Prover
Auxiliary Operation Switch
(i.e. Manual or Gas Pressure)
115 VAC Input From Disconnect Switch
Aux. Motor in parallel with H & N used for
additional Power Venter, Inducer, IN-FORCER Aux. Prover contacts in series with H & PH
contacts on output terminals
Appliance # 2
Interlock
Appliance # 1
Interlock
Appliance # 3
Interlock
MAC-3 CIRCUIT BOARD FEATURES
Aux. Limit switch in series with
optional limit on terminal strip Optional Alarm Sequencer proves Fan
Prover Operation (not limit operation)