LAARS EDN Series - Installation, Operation and Maintenance Instructions - Manual (Page 29)

Endurance Page 29
7. When there is a call for heat, the pump and
the blower will start, the display will show the
supply temperature. The appliance will attempt
to ignite three times, if ignition is not successful,
the appliance will lock out and display “LO”.
Ignition reset is done by pressing the reset button
on top of the control panel. EBP models will
continue to operate until the 20 gallon transfer
tank is up to temperature.
8. EBP only: Turn on a hot water tap. This puts the
appliance in the DHW mode.
Caution
Should any pronounced odor of gas be detected, or
if the gas burner does not appear to be functioning
in a normal manner, close main shutoff valve, do not
shut off switch, and contact your heating contractor,
gas company, or factory representative.
You MUST check flame monitoring control
(ignition system safety shut-off device).
9. Close gas shutoff valve with burner operating.
10. The gas valve status light will go out, and
immediately a new trial for ignition will begin.
The burner will not relight, because the gas is off.
The control will make two more attempts to light
the burner. Ignition will not occur, as the gas is
off. The boiler will lockout, and the display will
show “LO” after the gas valve has closed on the
third ignition attempt. The ignition control LED
will show a three-flash sequence.
11. Open gas shutoff valve. Press reset button on the
top of the control panel. The ignition sequence
will start again and the burner will start. The
appliance will return to its previous mode of
operation.
SECTION 8.
Maintenance and Component
Description
Figure 34 shows the location of the control
panel components. The parts sections show the other
components on the Endurance.
8.1 Unit Pump
The unit pump operates whenever there is a call
for heat or hot water.
It is a wetted-rotor type pump and should always
be filled with water when it is operating so that it will
cool properly.
If a pump change is required for any reason,
valve off the boiler and drain approximately 1 or 2
gallons (approx. 4-8L) of water from it. Turn off the
main disconnect switch and unplug the pump wires,
remove the pump motor. The pump housing need not
be removed. The replacement pump motor should be
installed in the reverse order from which the old pump
motor was removed. After filling the system be sure
the combustion chamber coil vents through the air vent
located on top of the boiler chamber (inlet manifold
extension).
8.2 Gas Valve
The gas valve is a 24VDC solenoid operated,
negative pressure regulated ratio valve. The outlet
pressure may be adjusted as described in the service
section. It is designed to operate with supply pressures
of 4-13 inches w.c. (1.0 to 3.2 kPa). To remove the
gas valve, shut off 120 volt power and the gas shutoff
valve, remove the 4 screws on the upper and lower
flanges and disconnect the wires from the gas valve,
the valve may now be removed. After the valve has
been removed, replace with a new valve in the reverse
order in which the old valve was removed. Turn on
gas shutoff valve and 120 volt power and check boiler
operation and gas tightness of gas valve connections.
8.3 Safety Limit Switch
The Safety Limit Switch is an automatic reset
switch with a fixed set point of 230°F (110°C).
To replace the switch, shut off the 120 volt power.
Disconnect the 2 wires from the quick connects at the
switch and remove the switch. To replace, perform the
same operations in reverse. Turn on disconnect switch
and check boiler.
8.4 Boiler Control
The Endurances uses an FX05 boiler control.
The control takes inputs from a domestic hot water
flow switch, an overheat thermostat (safety high
limit), external space heating switch, and temperature
sensors throughout the Endurance unit. Using these
signals, it works with the ignition control to ensure
proper and safe operation of the Endurance. It controls
call for heat, the modulating point for the blower, the
Endurance pump, and the signals that are sent to the
ignition control.
Figure 34. Control Panel.