21
LEAk CHECk
After gas piping is completed, carefully check all piping
connections (factory- and field-installed) for gas leaks. Use a
leak detecting solution or other preferred means.
NOTE:
If emergency shut-off is necessary, shut off the main
manual gas valve and disconnect the main power to the
furnace. The installer should properly label these devices.
Some soaps used for leak detection are
corrosive to certain metals. Carefully rinse
piping thoroughly after leak test has been
completed. Do not use matches, candles,
flame or other sources of ignition to check for
gas leaks.
CAUTION
!
Electrostatic discharge can affect electronic
components. Take precautions to neutralise
electrostatic charge by touching your hand
and tools to metal prior to handling the
control.
CAUTION
!
When testing pressure of gas lines, gas valve
must be disconnected and isolated. See figure
24. Gas valves can be damaged if subjected to
pressures greater than 1/2 psig (3.48 kPa, 14
inches w.c.).
IMPORTANT
!
The furnace must be isolated by closing its individual manual
shut off valve and disconnecting from the gas supply system
the during any pressure testing of the gas supply system at
pressures greater than 1/2 psig (3.48kPa, 14 inches w.c.).
MANUAL MAIN
SHUT-OFF VALVE
WILL NOT HOLD
NORMAL TEST
PRESSURE
CAP
ISOLATE
GAS VALVE
FURNACE
1/8 NPT PLUG
Figure 16
ELECTRICAL
A power wiring harness is shipped with each Lennox Merit
Series
™
furnace. An IEC receptacle is provided on the right
side of the unit. Plug the harness into the IEC receptacle and
into a properly sized wall plug.
Refer to figure 18 schematic wiring diagram.
1. Ensure that power connection point is located with 2m of
furnace.
2. Holes are on both sides of the furnace cabinet to facilitate
thermostat wiring.
3. Before connecting the thermostat wiring, check to make
sure the wires will be long enough for servicing at a
later date. Remove the blower access panel to check the
length of the wire.
4. Complete the wiring connections to the equipment. Use
the provided unit wiring diagram shown in Figure 18.
18-gauge wire or larger that is suitable for Class II rating
for thermostat connections.
5. Electrically ground the unit according to local codes.
NOTE:
The Lennox Merit Series
™
furnace contains
electronic components that are polarity sensitive. Make
sure that the furnace is wired correctly and is properly
grounded.
6. One line voltage “EAC” spade terminal is provided on the
furnace control board. Any electronic air cleaner rated up
to one amp can be connected to this terminal with the
neutral leg of the circuit being connected to one of the
provided neutral terminals. See figure 17 for control board
configuration. This terminal is energised when the indoor
blower is operating.
7. One line voltage “HUM” spade terminal is provided on the
furnace control board. Any humidifier rated up to one amp
can be connected to this terminal with the neutral leg of
the circuit being connected to one of the provided neutral
terminals. See figure 17 for control board configuration.
This terminal is energised in the heating mode when the
