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7.D
Field Connections
This boiler has three Field Connection Terminals.
TB1, TB2 and TB3
(TB3 is for optional equipment).
7.D.1 TB1 (Terminal Block 1) TT, DHW, OAS
7.D.1.a TT (Central Heat)
TT is for the end switch of a zone
relay control system or direct
thermostat connection. It controls
the boiler to maintain the central
heating. Do not connect directly
to three wire zone valves. Always
use an isolation relay or zone
valve controller (see Figure 26 and
Figure 27 on page 27).
Figure 18. Terminal Block Locations
TB3 -DHW Relay
Connections
(optional)
TB2 - 120 VAC
Outputs
TB1 -TT, DHW, OAS
7.D.1.b DHW
Either a tank aquastat or the leads from the optional DHW Relay Kit will control the boiler to the high limit setpoint.
See SECTION 8 for functionality.
7.D.1.c Field Interlocks
Field Interlocks allow for auxiliary limits or LWCO. Breaking these connections prevents the boiler from operating.
The LIMITS LED will flash while these connections are open.
7.D.1.d PV Terminals
PV1, PV2 and PV4 (PV Terminals) are for power venters or air make up equipment (See 7.E on page 26).
7.D.1.e WWSD + COM
10K ᾨ outdoor air sensor will allow the boiler to operate in economy mode with WWSD feature.
7.D.1.f OAS + COM
10K ᾨ outdoor air sensor provides outdoor reset control and warm weather shut down, based on control settings.
Figure 19. Unlocking the Cover
Figure 20. Field Connections (TB1)
Open
Closed
WARNING
No Power to be applied to terminals 10-12 of TB1.
Sensor Connections Only!
LAARS Heating Systems