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INSTALLATION
SL 80-399 MODULATING GAS BOILER
SL 26-260 G3, SL 40-399 G3 MODULATING GAS BOILERS
1.8 ELECTRICAL CONNECTIONS
All electrical wiring to the boiler (including grounding) must conform to local electrical
codes and/or to the National Electrical Code, ANS/NFPA No. 70 – latest edition, or to the
Canadian Electrical Code, C22.1 - Part 1.
1.8.1 120 VAC Line Voltage Hook-up
Line-voltage wiring is done within the field-wiring box. (Refer to Section 6.2.Wiring
Diagram on page 6-4). Connect the boiler to the grid power using a separate, fused circuit
and on/off switch within sight of the boiler. Use 14-gauge wire in BX cable or conduit
properly anchored to the boiler case for mains supply and pump circuits.
Connect a 120 VAC / 15 amp supply to the “AC IN” tagged leads in the wiring box. The
max. actual draw (with 5 typical residential size pumps) is less than 4 amps.
The 120 VAC power supply to the load pumps (P/V1, P/V2, P/V3, and P/V4) has been
factory installed and connected to P/V-L and P/V-N for your convenience. If you use the
P/V relay connections for zone valves, then the 120 VAC connections at P/V-L and P/V-N
will have to be removed and properly capped off. 24 VAC can then be applied using an
external transformer to supply power to zone valves. The upper 4 pairs of contacts on this
green connector strip are then powered to manage up to 4 load pumps – the top pair for
Load 1, the second pair for #2 etc. Once the controller is programmed for the respective
loads, the boiler manages all the loads without need of further relays (for loads up to 1/3
HP; for more – use a protective relay).
The boiler (primary) pump is connected to the White/Yellow pair labeled Primary Pump.
This lead is factory wired to the controller (and its 120 VAC supply) at the upper right
backside of the controller board. Do not attempt to connect the primary pump to the Pump/
Zone Valve Terminal Block along the controller’s right edge. This is for the secondary
pumps and/or zone valves only. Connect the pump’s Black wire to the Yellow of this
pair (switched Hot). The White/ Yellow pair should be individually capped if the primary
pump does not obtain its power from this pair (e.g. if a variable speed primary pump is
connected to the mains power).
Pumps can be switched on/off using the touchscreen controller, so there is no need for
temporary pump wiring during system filling / air purging. If pumps are hard-wired to the
panel during the system fill/purge phase, re-wire the boiler pump to the primary pump
leads inside the wiring box so the primary pump purge function is active.
In a new construction application, use a construction thermostat, or jumper with an in-line
on/off switch – for on/off management of the boiler. Do not just pull power from the unit,
or its moisture management routine will be interrupted (fan turns at ultra low rpm for 90
minutes after burner shutdown). Treat it like a computer, where you do not just pull the
plug when done. If a “low airflow / check vent” error signal shows, check for (and remove)
any water in the clear vinyl air reference tubes. This has been seen occasionally at
construction sites where the boiler has been repeatedly de-powered wet.
The combined current of all pumps connected through the on-board pump relays
should not exceed 10 amps. The control circuit board is protected using on-board field
replaceable fuses. Each pump is fused with a separate 5 Amp fuse. The Alarm contact is
fused with a 5 Amp fuse and the 24 VAC boiler control circuit is protected with a 2 Amp
fuse.
Line voltage leads for power supply,
primary pump and VS output
Line voltage load pump terminals
CAUTION
The internal pump relays are
protected with 5 Amp fuses. The
maximum recommended load
on each fuse is 4 Amps (80% of
rating). The maximum combined
pump load is 10 Amps. Isolation
relays or contactors MUST be
used if the loads exceed these
maximums.
