a.129 sec. to complete one revolution
b.3600/129 = 27.9
c.27.9 x 2 = 55.8 ft3 of gas flow/hr.
d.55.8 x 1050 = 58,590 Btuh input.
In this example, the nominal input rate for low stage is 58,500 Btu/hr, so the low stage manifold pressure is correctly set.
If the measured low stage rate is too low, increase the manifold pressure to increase rate. If the measured low stage rate is too high, decrease the manifold pressure to decrease rate.
NOTE:
4.Verify proper low stage gas heat temperature rise.
a.Furnace must operate within rise range listed on rating plate.
b.Select ”COMFORT” or ”EFFICIENCY” mode on UI. ”COMFORT” mode will provide a warmer supply air temperature, while ”EFFICIENCY” will provide lower gas consumption.
c.Make sure access panel is
d.Measure supply and return temperatures as close to the unit as possible. Subtract the return temperature from the supply temperature to determine rise. Rise should fall within the range specified on the rating plate.
5.Adjust manifold pressure to obtain high stage input rate (See Fig. 19).
a.Set unit to run for 20 minutes in
b.Remove regulator adjustment cap from high stage gas valve pressure regulator (See Fig. 19) and turn
NOTE: DO NOT set high stage manifold pressure less than 3.2 IN. W.C. or more than 3.8 IN. W.C. for natural gas. If manifold pressure is outside this range, change main burner orifices.
c.
d.Leave manometer connected.
6.Verify natural gas high stage input rate.
a.Turn off all other gas appliances and pilots served by the gas meter.
b.If unit is not running, set unit to run for 20 minutes in high stage gas heat operation using the ”INSTALLER CHECKOUT” menu on the UI.
c.Record number of seconds for gas meter to complete 1 revolution.
d.Divide number of seconds in step c. into 3600 (number of seconds in 1 hour).
e.Multiply result of step d. by the number of cubic feet shown for one revolution of test dial to obtain cubic feet of gas flow per hour.
f.Multiply result of step f. by Btu heating value of the gas to obtain total measured input shown in Table 6. (Consult the local gas supplier if the heating value of gas is not known).
EXAMPLE: Assume a 90,000 high stage input unit is being installed. Assume that the size of the dial is 2 cubic ft., one revolution takes 84 sec., and the heating value of the gas is 1025 Btu/ft3. Proceed as follows:
a.84 sec. to complete one revolution
b.3600/84 = 42.9
c.42.9 x 2 = 85.8 ft3 of gas flow/hr.
d.85.8 x 1050 = 90,090 Btuh input.
In this example, the nominal input rate for high stage is 90,000 Btu/hr, so the high stage manifold pressure is correctly set.
If the measured high stage rate is too low, increase the manifold pressure to increase rate. If the measured high stage rate is too high, decrease the manifold pressure to decrease rate.
NOTE:
7.Verify proper high stage gas heat temperature rise.
a.Furnace must operate within rise range listed on rating plate.
b.Make sure access panel is
c.Measure supply and return temperatures as close to the unit as possible. Subtract the return temperature from the supply temperature to determine rise. Rise should fall within the range specified on the rating plate.
NOTE: If the temperature rise is outside the rating plate range, |
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first check: |
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a. Gas input for low and high stage gas heat operation. | A | |
b. Derate for altitude, if applicable. | ||
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c. Return and supply ducts for excessive restrictions | 577D | |
causing static pressures in excess of .5 IN. W.C. | ||
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d. Make sure model plug is installed. |
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8. Final Check |
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a. Turn off gas to unit |
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b. Remove manometer from pressure tap. |
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c. Replace pipe plug on manifold (See Fig. 20). |
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d. Turn on gas to unit. |
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e. Check for leaks. |
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CHECK GAS INPUT (PROPANE GAS) |
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Refer to propane kit installation instructions for properly checking |
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gas input. |
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NOTE: For installations below 2,000 ft (610 m), refer to the unit |
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rating plate for proper propane conversion kit. For installations |
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above 2,000 ft (610 m), contact your distributor for proper propane |
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conversion kit. |
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CHECK BURNER FLAME |
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With control access panel removed (See Fig. 24), observe the unit |
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heating operation. Watch the burner flames to see if they are light |
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blue and soft in appearance, and that the flames are approximately |
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the same for each burner. Propane will have blue flame (See Fig. |
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21). Refer to the Maintenance section for information on burner |
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removal. |
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Pipe Plug | Manifold |
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A09082
Fig. 20 - Burner Assembly
27