Strebel S-FX 125, Installation Operating & Maintenance Manual

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3 TECHNICAL DATA FOR S-FX BOILERS
3.1 Functional introduction
The S-FX boilers is a high efficiency, low emissions premix condensing heat generator for heating, running on
natural gas or LPG and equipped with a microprocessor control system.
The boiler body consists of a patented stainless-steel helical tube heat exchanger and a premix burner in stainless
steel, equipped with electronic ignition with ionisation flame control, modulating fan and modulating gas valve.
The S-FX is a heat generator arranged to operate alone or in cascade.
The S-FX boiler is standard set for Natural Gas (G20).
Boiler control includes:
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Cascade control for up to six boilers.
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Remote operation and heat demand indication from each boiler.
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Weather compensation control.
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Calorifier control.
Connections for:
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On/Off thermostat.
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0-10 VDC remote flow temperature (set point)
control.
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0-10 VDC remote burner input control.
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Outdoor temperature sensor.
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External calorifier pump or diverter valve.
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Boiler pump.
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System pump.
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External flow switch or external safety device.
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External system sensor.
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DHW indirect sensor or DHW control thermostat.
Cascade control
When using the integrated cascade control, a maximum of six boilers can be controlled in a cascade
configuration. Using an appropriate external control, this number may be increased at will.
0-10 VDC connection available
The boiler flow temperature or power input can be controlled by an external 0-10 VDC signal. When a number of
boilers are cascaded, and controlled by the integrated cascade control, the signal should be directed to the master
boiler only. If an alternative control is used, more than one boiler may be controlled by a 0-10 VDC signal.
Time program
For both central heating and hot water function of the boiler, time programs with six programmable periods per day
are available. These time programs are set and activated by entering the desired settings directly at the boiler
control panel.