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935SB: Installation, Start-up, Operating and Service Maintenance Instructions
Prime Condensate Trap with Water
CAUTION
!
UNIT OPERATION HAZARD
Failure to follow this caution may result in intermittent unit operation
or performance satisfaction.
Condensate trap must be PRIMED or proper draining may not occur.
The condensate trap has two internal chambers which can ONLY be
primed by pouring water into the inducer drain side of condensate trap.
1. Remove upper and middle collector box drain plugs opposite of the
condensate trap.
2. Connect field-supplied 5/8-in. (16 mm) ID tube with attached
funnel to upper collector box drain connection.
3. Pour one quart (liter) of water into funnel/tube. Water should run
through collector box, overfill condensate trap, and flow into open
field drain.
4. Remove funnel; replace collector box drain plug.
5. Connect field-supplied 5/8-in. (16 mm) ID tube to middle collector
box drain port.
6. Pour one quart (liter) of water into funnel/tube. Water should run
through collector box, overfill condensate trap, and flow into open
field drain.
7. Remove funnel and tube from collector box and replace collector
box drain plug.
Fig. 63 – Prime Condensate Trap
Adjustments
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in injury, death and/or
property damage.
DO NOT bottom out gas valve regulator adjusting screw. This can
result in unregulated gas valve outlet pressure and result in excess
overfire and heat exchanger failures.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace life.
DO NOT redrill orifices. Improper drilling (burrs, out-of-round holes,
etc.) can cause excessive burner noise and misdirection of inlet gas.
(see
Fig.
64)
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Furnace gas input rate on rating plate is for installation at altitudes up to
2,000 ft. (610 M). Furnace input rate must be within +/-2 percent of
furnace rating plate input.
The input rating for altitudes above 2,000 ft. (610 M) must be reduced by
2 percent for each 1,000 ft. (305 M) above sea level. For installations
below 2,000 ft. (610 M), refer to the unit rating plate. For installation
above 2,000 ft. (610 M), multiply the input on the rating plate by the
derate multiplier for the correct input rate
Table 25 – Altitude Derate Multiplier for USA
ALTITUDE
(FT. / M)
0–2000 (0-610)
2001–3000 (610-914)
3001–4000 (914-1219)
4001–5000 (1219-1524)
5001–5400 (1525-1646)
*Derate multiplier factors are based on midpoint altitude for altitude range.
Determine the correct gas input rate. Refer to the unit rating plate.
Determine the correct outlet gas pressure adjustment.
1. Obtain average yearly gas heat value (at installed altitude) from
local gas supplier.
2. Obtain average yearly gas specific gravity from local gas supplier.
A190304
3. Find closest natural gas heat value and specific gravity
through
Table
30).
4. Follow heat value and specific gravity lines to point of intersection
to find outlet pressure setting for proper operation.
Check Inlet Gas Pressure
The inlet gas pressure must be checked with the furnace operating. This
is necessary to make sure the inlet gas pressure does not fall below the
minimum pressure of 4.5 in. w.c.
1. Make sure the gas supply is turned off to the furnace and at the
electric switch on the gas valve
2. Loosen set screw on inlet tower pressure tap no more than one full
turn with a 3/32−in. hex wrench or remove the 1/8−in. NPT plug
from the inlet pressure tap on the gas valve.
3. Connect a manometer to the inlet pressure tap on gas valve.
4. Turn on furnace power supply.
5. Turn gas supply manual shutoff valve to ON position.
6. Turn furnace gas valve switch to ON position.
7. Jumper R and W thermostat connections at the furnace control
board.
8. When main burners ignite, confirm inlet gas pressure is between 4.5
in. w.c. (1125 Pa) and 13.6 in. w.c. (3388 Pa).
9. Remove jumper across thermostat connections to terminate call for
heat. Wait until the blower off delay is completed.
50
Fig. 64 – Orifice Hole
(Table
25).
PERCENT
OF
MULTIPLIER
DERATE
0
4–6
6–8
8–10
10–11
A180238
DERATE
FACTOR*
1.00
0.95
0.93
0.91
0.90
(Table 27
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