Tempstar F8MTL, Руководство по установке, Страница: 45 / 52

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441 01 2101 05
Specifications are subject to change without notice.
(4.) Insert brush end of cable in burner inlet opening
of cell, and proceed to clean 2 lower passes of cell
in same manner as upper pass.
(5.) Repeat foregoing procedures until each cell in
furnace has been cleaned.
(6.) Using vacuum cleaner, remove residue from
each cell.
(7.) Using vacuum cleaner with soft brush
attachment, clean burner assembly.
(8.) Clean flame sensor with fine steel wool.
(9.) Install NOx baffles (if removed.)
(10.) Reinstall burner assembly. Center burners in cell
openings.
10. Remove old sealant from cell panel and collector box
flange.
11. Spray releasing agent on the heat exchanger cell panel
where collector box assembly contacts cell panel.
NOTE : A releasing agent such as a vegetable oil cooking
spray that does not contain corn oil, canola oil, halogenated
hydrocarbons or aromatic content, which may prevent an
inadequate seal from occuring, and RTV sealant such as
G.E. RTV 162, G.E. RTV 6702, or Dow − Corning RTV 738
sealant are required. DO NOT substitute any other type of
RTV sealant.
12. Apply new sealant to flange of collector box and attach
to cell panel using existing screws, making sure all
screws are secure.
13. Reconnect wires to the following components (Use
connection diagram on wiring label, if wires were not
marked for reconnection locations.):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switches.
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame − sensing electrode.
h. Flame rollout switches.
14. Reinstall internal vent pipe, if applicable.
15. Reinstall vent connector on furnace vent elbow.
Securely fasten vent connector to vent elbow with 2
field − supplied, corrosion − resistant, sheet metal screws
located 180 apart.
Figure 53 − Igniter Position − Top View
A05026
16. Replace blower access door only, if it was removed.
17. Set thermostat above room temperature and check
furnace for proper operation.
18. Verify blower airflow and speed changes between
heating and cooling.
19. Check for gas leaks.
20. Replace outer access door.
Figure 54 − Cleaning Heat Exchanger Cell
A91252
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made
specifically for the detection of leaks to check all
connections.
!
WARNING
Step 3 — Sequence of Operation
NOTE : Furnace control must be grounded for proper
operation or control will lockout. Control is grounded through
green wire connected to gas valve and burner bracket screw.
Using the schematic diagram in Figure 55, follow the
sequence of operation through the different modes. Read and
follow the wiring diagram very carefully.
NOTE : If a power interruption occurs during a call for heat
(W/W1 or W/W1 − and − W2), the control will run the blower for
the selected heat off − delay period two seconds after power is
restored, if the thermostat is still calling for gas heating. The
LED light will flash a status code 1+2 during this period, after
which the LED will switch to a heartbeat, as long as no faults
are detected. After this period, the furnace will respond to the
thermostat normally.
The blower door must be installed for power to be conducted
through the blower door interlock switch ILK to the furnace
control CPU, transformer TRAN, inducer motor IDM, blower
motor BLWM, hot − surface igniter HSI, and gas valve GV.
1. Two − Stage Heating with Single − Stage Thermostat
(See Figure 23 or Figure 32 for thermostat
connections)
NOTE : The thermostat type switch (TT) selects either the
two − stage thermostat operation mode when ON, (see item 2)
or the single stage thermostat operation mode when OFF in
response to a call for heat. When the W2 thermostat terminal
is energized it will always cause high − heat operation when
the R to W circuit is closed, regardless of the setting of the
thermostat type switch. This furnace can operate as a
two − stage furnace with a single − stage thermostat because
the furnace control CPU includes a programmed sequence of
controlled operation, which selects low − heat for the first 12
minutes of operation then switches to high heat operation.
If the power is interrupted, the control CPU will operate in low
heat for 12 minutes then it will switch to high − heat, as long as
the thermostat continues to call for heat.
The wall thermostat “calls for heat”, closing the R to W circuit.
The furnace control performs a self − check, verifies the
low − heat and high − heat pressure switch contacts LPS and
HPS are open, and starts the inducer motor IDM in
high − speed. The HUM terminal is energized for a 115V
humidifier (if used).