Description Of The Appliance; Safety Devices - Riello Condexa PRO NA 75P Installation, Operation And Service Manual

1.4 Description of the appliance

The Condexa PRO NA it is a condensing, pre-mixed thermal mod-
ule consisting in a modulating thermal element.
It's available in two models of power: 75 kW (255.900 BTU/hr) and
117 kW (399.000 BTU/hr).
Optimal combustion management supports high thermal effi-
ciencies (Over 95%) and low polluting emissions.
The boiler is designed for sealed chamber operation.
The appliance in standard configuration is for indoor installation
to guarantee an IPX4D protection level.
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The Condexa PRO NA boilers can be cascaded to reach a max-
imum power of 2.388.500 btu/hr. (700 KW).
The appliance's key technical features are
− helicoidal heat exchanger with a double coil smooth stain-
less steel pipe, to guarantee good corrosion resistance and
the option of operating with high ∆ts (up to 104°F [40°C]),
reducing system set-up times;
− maximum exhaust flue exit temperature 212°F [100°C];
− microprocessor management and control with self-diag-
nostics, shown by means of a display, and logging of main
errors;
− Anti-Frost function;
− pre-settings for room/heat demand thermostat for low
and high temperature ranges;
− option to manage a CH circuit and a DHW circuit with stor-
age tank;
− high-efficiency and high residual discharge head circula-
tor;
− climate control function (available only when using the
outdoor temperature sensor accessory).

1.5 Safety devices

All appliance functions are electronically controlled by a dual pro-
cessor technology board.
Any malfunction results in the appliance being shut down and the
automatic closure of the gas valve.
The following is installed on the CH water circuit:
− Safety high-limit thermostat.
− Flow sensor capable of monitoring the main heating cir-
cuit's flow on an ongoing basis and of stopping the appli-
ance in the event of insufficient flow.
− Temperature sensors on supply and return lines that mea-
sure the temperature difference (∆t) between input and
output fluid and allow the boiler to fire when a demand
is made.
− Minimum pressure switch.
The following is installed on the combustion circuit:
− Gas solenoid with pneumatic gas flow compensation de-
pending on the suction line's air flow rate.
− Ignition/detection electrode.
− Flue gas temperature sensor.
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WARNING: The triggering of safety devices indicates the mal-
function of a potentially hazardous situation. Therefore, con-
tact a service agency immediately. After a brief pause, it is
possible to try and restart the appliance (see section "Initial
startup").
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WARNING: Safety devices must be a qualified installer, service
agency or gas supplier, using only original parts. Refer to the
spare parts catalogue supplied with the appliance. After mak-
ing the repair, check that the appliance is working properly.
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WARNING: The appliance must not be put in service, even
temporarily, when tampered safety devices are not in opera-
tion or have been tampered with.
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A low water cutoff may be required by state local code or some
insurance companies. Check code requirements before instal-
lation of the Condexa PRO NA boiler. If required:
− Use a low water cutoff designed for hydronic installations;
− Follow low water cutoff manufacturer's instructions.
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A hot water boiler installed above the radiation level or as re-
quired by the Authority having jurisdiction, must be provided
with a low water cutoff device either as part of the boiler or at
the time of boiler installation.
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GENERAL INFORMATION