Bryant 577D----A Fire and Unit Damage Hazard, Altitude Derate Multiplier for U.S.A, Canada

!WARNING

CARBON MONOXIDE POISONING HAZARD

Failure to follow this warning could result in personal injury and/or death.

If the manifold pressure and/or gas rate is not properly adjusted on HI and LO stages, excess carbon monoxide can be produced.

!WARNING

FIRE AND UNIT DAMAGE HAZARD

Failure to follow this warning could result in personal injury or death and/or property damage.

Unsafe operation of the unit may result if manifold pressure is outside of the ranges listed in Table 6.

b.When the gas supply being used has a different heating value or specific gravity, refer to national and local codes, or contact your distributor to determine the required orifice size.

2.Adjust manifold pressure to obtain low stage input rate (See Fig. 19).

a.Turn off gas supply to unit.

b.Remove pipe plug on manifold (See Fig. 20 and connect manometer). Turn on gas supply to unit.

c.Turn gas valve switch to ON.

d.Set unit to run for 20 minutes in low-stage gas heat operation using the ”INSTALLER CHECKOUT” menu on the User Interface.

e.Remove regulator adjustment cap from low stage gas valve pressure regulator (See Fig. 19) and turn low-stage adjusting screw (3/16 or smaller flat-tipped screwdriver) counterclockwise (out) to decrease rate and clockwise (in) to increase input rate.

577D-- -- A

Gas input rates on rating plate are for installations at altitudes up to 2000 ft (610 m). Input rate must be within ± 2% of rating plate input.

1.Determine the correct gas input rate.

a.The rated gas inputs shown in Table 6 are for altitudes from sea level to 2000 ft (610 m) above sea level. These inputs are based on natural gas with a heating value of 1025 Btu/ft3 at .60 specific gravity.

IN THE U.S.A.:

The input rating for altitudes above 2,000 ft (610 m) must be reduced by 4 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 installations above 2,000 ft, (610 m) multiply the input by on the rating plate by the derate multiplier in Table 5 for the correct

ON/OFF SWITCH

INLET PRESSURE TAP

REGULATOR COVER SCREW

PLASTIC ADJUST SCREW

REGULATOR SPRING

HIGH STAGE GAS

PRESSURE REGULATOR

ADJUSTMENT

LOW STAGE

GAS PRESSURE

REGULATOR ADJUSTMENT

MANIFOLD

PRESSURE TAP

A04167

input rate.

Table 5 – Altitude Derate Multiplier for U.S.A*.

Altitude ft (m)		Percent of Derate	Derate Multiplier
			Factor{
0-2000		0	1.00
(0-610)
2001-3000*		8--12	0.90
(610	-914)
3001	-4000	12--16	0.86
(915-1219)
4001	-5000	16--20	0.82
(1220	-1524)
5001	-6000	20--24	0.78
(1524	-1829)
6001	-7000	24--28	0.74
(1829	-2134)
7001	-8000	28--32	0.70
(2134	-2438)
8001	-9000	32--36	0.66
(2139	-2743)
9001-10,000		36--40	0.62
(2744	-3048)

* In Canada see Canadian Altitude Adjustment.

{Derate multiplier factors are based on midpoint altitude for altitude range.

IN CANADA:

The input rating for altitudes from 2,000 (610 m) to 4,500 ft (1372

m)above sea level must be derated 10 percent by an authorized Gas Conversion Station or Dealer.

EXAMPLE:

90,000 Btuh Input Furnace Installed at 4300 ft (1372 m).

Furnace Input Rate		Derate Multiplier		Furnace Input Rate
at Sea Level	X	Factor	=	at Installation
Altitude
90,000	X	0.90	=	81,000

Fig. 19 - Redundant Automatic Gas Control Valve

NOTE: DO NOT set low stage manifold pressure less than 1.4 IN. W.C. or more than 2.0 IN. W.C. for natural gas. If manifold pressure is outside this range, change main burner orifices.

f.Re-install low stage regulator adjustment cap.

g.Leave manometer connected.

NOTE: If orifice hole appears damaged or it is suspected to have been re-drilled, check orifice hole with a numbered drill bit of the correct size. Never re-drill an orifice. A burr-free and squarely aligned orifice hole is essential for proper flame characteristics.

3.Verify natural gas low 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 low-stage gas heat operation using the ”INSTALLER CHECKOUT” menu on the UI.

c.Record number of seconds for gas meter to complete one 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 129 sec., and the heating value of the gas is 1025 Btu/ft3. Proceed as follows:

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