INSTALLATION AND OPERATION INSTRUCTIONS
1-30
SL 80-399 MODULATING GAS BOILER
SL 26-260 G3, SL 40-399 G3 MODULATING GAS BOILERS
NOTE
The IBC Touch-Screen controller
has the ability to connect to most
power stealing thermostats. See
the
V-10 Touchscreen Boiler
Controller
manual for details.
NOTE
The IBC boiler (like any modern
appliance that contains
electronic equipment), must have
a “clean” power supply, and is
susceptible to power surges
and spikes, lightning strikes and
other forms of severe electrical
“noise”. Power conditioning
equipment (surge protectors,
APC or UPS devices) may be
required in areas where power
quality is suspect.
DANGER
Do not connect thermistor
sensors to “Therm” terminals.
An overheating hazard can result
in serious personal injury and/or
property damage.
See Controller
Manual section 2.1.1 for detailed
instructions.
1.8.2 Power Quality and Electrical Protection
In areas of unreliable power, appropriate surge protectors and or power conditioning
equipment should be installed in powers supply wiring circuits.
1.8.3 Zone Valve Hook-up
If zone valves rather than pumps are used to manage multiple heating loads, then 24
VAC for the zone valves should be provided to the power contacts on the Pump/ Zone
Valve Terminal Block. Disconnect the 120 VAC leads connected to PV-L/PV-N and cap off.
Use a separate transformer – the 40 VA unit inside the wiring box is for internal systems
only. The individual load/zone valves are then to be wired to their associated contacts on
the secondary pump/zone valve connector. Do not confuse such “load/zone valves” with
similar valves used to segregate a single load type (e.g. those used on a zoned radiant
floor) – see next section.
1.8.4 Thermostat / Sensor Wiring
Dry contacts for thermostats for each of the four loads are provided as marked on the
lower connector strip (e.g. “Therm 1”). Gang lines from a multiple-zoned load (e.g. off
the end-switches for each radiant floor zone) present a common thermostat signal to the
controller. Ensure that there are no disturbing influences on the call-for-heat lines - e.g.,
that no coils to switch an air handler motor. Most power stealing thermostats can be
connected directly to the Therm terminals.
See the V-10 Touchscreen Boiler Controller
manual for more detailed instructions.
1.8.5 Other Wiring
Other optional low voltage connections to the control board include:
• Two auxiliary interlocks - for external safety devices as may be required by some
jurisdictions, such as a low water cutoff or a low gas pressure cut-out (for off-grid
propane). A floor-protecting aquastat (water temperature control) can use one of these,
to cause a full boiler shutdown in the case of excess floor temperature.
• Contacts for indoor and outdoor temperatures sensors associated with reset heating.
A 10K ohm thermister (resistor dependent on temperature) for outdoor reset sensing is
supplied with the boiler for improved comfort and combustion efficiency.
• One pair for a DHW tank sensor. Connect to “DHW S” (not the respective Therm.
1,2,3,4 location) and the boiler automatically detects and calls a smart DHW routine.
• One pair of contacts for remote secondary loop temperature control.
• One pair (marked BoilerNet) for network connection – this is used for connecting
multiple SL and/or VFC modulating units for autonomous staging.
• The bottom pair of contacts receives a 0-10VDC (default) or 4-20 mA signal from an
external boiler controller for direct throttle control. The boiler’s own sensors act as high
limits only. The user must enter maximum and minimum boiler supply temperatures.
NOTE:
Sensors connected to any sensor input contacts must be of the NTC Thermister
type with a resistance of 10,000 ohms at 77°F (25°C) and β = 3892. We do not
recommend using 3rd party supplied sensors. Compatible water temperature sensors and
outdoor sensors can be supplied by your IBC distributor.
