LAARS Rheos RHCV - Install and Operating Manual - Manual (Page 41)

Rheos Boiler and Water Heater Page 41
determined the actuator is working properly, the gas
valve body may need to be replaced. To remove the
gas valve body, shut off 120-volt power and the gas
shutoff valve. Remove the front and right-side panels
from the unit. Disconnect the union between the
valve body and the blower. Label the four pressure
tubes that are connected to the valve actuator, to
ensure that they will replaced correctly. Remove
the valve actuator, per the instructions above. Unscrew
the valve body from the gas train. After the valve has
been removed, replace with a new valve in the reverse
order. Turn on gas shutoff valve and 120 volt power
and check appliance operation and tightness of gas
valve connections.
7.2.4 Safety Gas Valve
The safety gas valve is a 24-volt diaphragm
valve. It is designed to operate with supply pressures
of 4-14 inches w.c. (1.0 to 3.4 kPa). To remove the gas
valve, shut off 120-volt power. Shut off the main gas
supply to the unit. Disconnect the gas supply piping
from the back of the unit. Disconnect the electrical
wires from the valve, and unscrew the gas valve from
the gas train. Re-assemble in reverse order. A bleed
line from the diaphragm type automatic valve shall be
vented per local code requirements.
7.2.5 Manual Reset High Limit Control
The high limit switch is manual reset switch with
an adjustable set point, up to 240°F (116°C) on boiler
models and 200°F (93°C) water heater models. To
replace the switch, shut off the 120-volt power to the
appliance. Remove the cover from the switch to access
the mounting screws. Remove the screws, and pull the
switch off the control panel. Replace in reverse order.
7.2.6 Temperature Control
The temperature control consists of an adjustable
electronic control and digital display module. To
replace the control or the display, shut off the 120-
volt power to the appliance. Remove the cover from
the control panel, and remove the screws from the
DIN rail clip, to which the controls are mounted. Pull
the electrical connector from the controller. Slide the
controllers from the DIN rail clip. Replace in reverse
order.
7.2.7 Ignition Control
The ignition control ensures the proved
interrupted-type ignition system. It controls the
hot surface ignitor and proves that the flame signal
is appropriate for powering the gas valves. It also
controls the blower’s pre-purge and post-purge. To
replace the control, shut off the 120-volt power to the
appliance. Remove the cover from the control panel.
Remove the electrical connectors from the ignition
control. Take out the controller’s mounting screws, and
pull the controller out. Replace in reverse order.
See Figures 36, 37 and 38 for location of gas
train and control components.
The gas and electric controls on the appliance
are engineered for long life and dependable operation,
but the safety of the equipment depends on their
proper functioning. It is strongly recommended that
a qualified service technician inspect the basic items
listed below every year.
a. Ignition control
b. Water temperature control
c. Automatic gas valve
d. Pressure switches
e. Blower
7.2.1 Burner
Check the burner for debris. Remove the fan
assembly to access the burner. Remove the 6 nuts,
which hold the burner in place. Pull burner up and out.
Clean burner, if necessary, by blowing compressed air
from the outside of the burner into the center of the
burner, and wipe the inside of the burner clean with
glass cleaner. A dirty burner may be an indication
of improper combustion or dirty combustion air.
Determine the cause, and correct. Always replace the
burner gasket when replacing the burner.
7.2.2 Filter
The filter used in the Rheos is washable with an
83% arrestance. Since the filter is washable, it will
only need replacement in very rare cases. If filter
replacement is needed, it should only be replaced with
factory parts. To access the filter, remove the unit’s
front panel. Disengage latch on top of filter box and
remove the filter box cover. Inspect the air filter. If
there is debris on the air filter, remove it from the filter
box, and wash it with mild soap and water. Ensure
that the filter is completely dry before re-installing, in
reverse order.
7.2.3 Modulating Gas Valve
The modulating gas valve consists of a valve
body and a pressure regulating electro-hydraulic
actuator. It provides the air/gas ratio control for the
unit. It is designed to operate with supply pressures of
4-13 inches w.c. (1.0 to 3.2 kPa).
To remove the valve actuator, shut off 120-volt
power and the gas shutoff valve. Remove the front
panel from the unit. Label the four pressure tubes
that are connected to the valve actuator, to ensure
that they will be replaced correctly. Remove the
four tubes from the barb connectors. Disconnect the
110-volt wires from the actuator. Remove the valve
actuator by taking out the four screws, and pulling the
actuator out. Re-install in reverse order. Turn on gas
shutoff valve and 120 volt power and check appliance
operation and tightness of gas valve connections.
The gas valve body will rarely have to be
removed. If there is a valve problem, and it has been