Set Temperature Rise - Carrier 58UHV Installation, Start-Up, And Operating Instructions Manual

(2.) Obtain average yearly specific gravity for local gas
supply.
(3.) Verify furnace model. Table 11 can only be used for
models 58UHV and 58UXV Furnaces.
(4.) Check and verify orifice size in furnace. NEVER
ASSUME THE ORIFICE SIZE. ALWAYS CHECK
AND VERIFY.
(5.) Find natural gas heat value and specific gravity in
Table 11.
(6.) Follow heat value and specific gravity lines to point of
intersection. Find orifice size and manifold pressure
settings for proper operation at given natural gas
conditions on low and high stages.
EXAMPLE:
Heat value = 980 Btu/cu ft
Specific gravity = 0.62
Therefore: Orifice No. 44*
Manifold pressure 3.5-in. wc on high stage and 1.5-in. wc
on low stage.
* The furnace is shipped with No. 45 orifices. Therefore, in
this example all main burner orifices must be changed and
manifold pressure must be adjusted.
(7.) Proceed to item c. to adjust manifold pressure.
b. Check gas input rate by clocking gas meter for low and
high stage.
(1.) Obtain average yearly heat value for local gas supply.
NOTE: Be sure heating value used for calculations is correct for
your altitude. Consult local gas utility for altitude adjustments (if
any) of gas heating value.
(2.) Check and verify orifice size in furnace. NEVER
ASSUME THE ORIFICE SIZE. ALWAYS CHECK
AND VERIFY.
(3.) Turn off all other gas appliances and pilots.
(4.) Turn SW-2 to ON. Close R-W/W1 and jumper R to
W2 to start furnace in high stage and let run for 3
minutes.
(5.) Measure time (in sec) for gas meter to complete 1
revolution.
(6.) Refer to Table 12 for gas rate (cubic ft of gas per hr).
(7.) Multiply gas rate (cubic ft/hr) by heating value (Btu/
cubic ft).
EXAMPLE:
Btu/hr heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 1070 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 72 sec
Gas rate = 100 cu ft/hr (from Table 12)
Btu/hr heating input = 100 X 1070 = 107,000 Btuh
(8.) Remove jumper R to W2 and repeat items (5.) through
(7.) for low stage.
NOTE: High altitude—In the United States, gas input on rating
plate is for altitudes up to 2000 ft. for natural and propane gases.
Ratings for altitudes over 2000 ft MUST be reduced 4 percent for
each 1000 ft above sea level. To obtain the adjusted altitude rating,
adjust the manifold pressure (see item c.) and replace the main
burner orifices as needed. Refer to NFGC Appendix F, Table F-4
for proper orifice sizing at high altitudes. Installations at altitudes
5500 feet or higher above sea level shall use a factory-supplied
high-altitude conversion kit. In Canada, gas input on rating plate is
for altitudes up to 2000 ft for natural and propane gases. High-
altitude ratings are from 2000 ft to 4500 ft above sea level.
High-altitude rating includes a 10 percent derate as required by
Canadian standards.
(9.) Measured gas inputs should equal low- and high-stage
gas inputs on unit rating plate ± 2 percent.
(10.) Proceed to item c. to adjust manifold pressure.
DO NOT redrill burner orifices. Improper drilling (burrs, out-
of-round, etc.) can cause excessive burner operating noise and
misdirection of burner flames. This could result in flame
impingement on burners and heat exchanger surfaces, leading
to potential failures.
c. Adjust gas manifold pressure
(1.) Move SW-2 to the ON position to lock out the
adaptive algorithm. (See Fig. 13 and 14.) Jumper R to
W/W1 and W2 to call for high stage.
(2.) Remove gas control regulator adjustment seal caps.
(See Fig. 17.)
(3.) Turn high-fire adjusting screw (5/64-in. hex allen
wrench) counterclockwise (out) to decrease input rate
or clockwise (in) to increase rate. When adjusting
input rate, DO NOT set manifold pressure less than
3.2-in. wc or more than 3.8-in. wc for natural gas. If
manifold pressure is outside this range, change main
burner orifices.
(4.) Remove R-to-W2 jumper to place furnace in low-stage
operation for low-stage adjustment.
(5.) Turn low-stage adjusting screw (5/64-in. hex allen
wrench) counterclockwise (out) to decrease input rate
or clockwise (in) to increase rate. When adjusting
input rate, DO NOT set manifold pressure less than
1.3-in wc or more than 1.7-in. wc for natural gas. If
manifold pressure is outside this range, change main
burner orifices.
NOTE: If orifices are changed, both high- and low-stage input
rates must be readjusted, with manifold pressures within ranges
specified in items (3.) and (5.).
NOTE: If orifice appears damaged or it is suspected to have been
redrilled, check the orifice size with a numbered drill bit of the
correct size. Never use a redrilled orifice. A burr-free and squarely
aligned orifice is essential for proper flame characteristics.
(6.) Remove jumper on R-W/W1 after low-stage adjust-
ments.
(7.) When correct input is obtained, replace regulator seal
caps. Main burner flame should be clear blue, almost
transparent. (See Fig. 18.)
2. Set air temperature rises.
Place SW-2 in ON position. Jumper R to W/W1 and W2 to
check high-stage temperature rise. To check low-stage tem-
perature rise, remove jumper to W2. Determine air tempera-
ture rises for both high and low stages. Do not exceed
temperature rise ranges specified on unit rating plate for high
and low stages.
a. Place duct thermometers in return and supply ducts as near
furnace as possible. Be sure thermometers do not see heat
exchangers so that radiant heat will not affect thermometer
readings. This is particularly important with straight run
ducts.
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