Bryant 345MAV instruction manual Ðaltitude Derate Multiplier for U.S.A, Example

ON AND

OFF SWITCH

GAS

PRESSURE

REGULATOR

ADJUSTMENT

BURNER

ENCLOSURE

REFERENCE

PRESSURE

TAP

BURNER

ORIFICE

INLET

PRESSURE TAPMANIFOLD PRESSURE TAP

A95622

Fig. 40ÐRedundant Automatic Gas Valve

b. Remove cap that conceals adjustment screw for gas valve regulator. (See Fig. 40.)

c.Turn adjusting screw, counterclockwise (out) to decrease manifold pressure or clockwise (in) to increase manifold pressure.

NOTE: This furnace has been approved for a manifold pressure of 3.2 in. wc to 3.8 in. wc when installed at altitudes up to 2000 ft. For altitudes above 2000 ft, the manifold pressure can be adjusted from 2.0 in. wc to 3.8 in. wc.

CAUTION: DO NOT bottom out gas valve regulator adjusting screw. This can result in unregulated manifold pressure and result in excess overfire and heat exchanger failures.

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

d.Replace gas valve regulator adjustment screw cap.

e.Replace burner enclosure front and verify adjusted gas input rate using method outlined in item 3.

f.Look through sight glass in burner enclosure and check burner flame. Burner flame should be clear blue, almost transparent. (See Fig. 41.)

3. Verify natural gas input rate by clocking gas meter.

NOTE: Be sure all pressure tubing, combustion-air and vent pipes, and burner enclosure front are in place when checking input by clocking gas meter.

NOTE: High-Altitude Adjustment

UNITED STATES

At altitudes above 2000 ft, this furnace has been approved for a 2% derate for each 1000 ft above sea level. See Table 8 for derate multiplier factor.

EXAMPLE:

100,000 Btuh input furnace installed at 4300 ft.

Furnace Input Rate		Derate		Furnace Input Rate
	X	Multiplier	=	at Installation
at Sea Level
		Factor		Altitude
100,000	X	0.91	=	91,000

A93059

CAUTION: DO NOT redrill orifices. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive burner noise and misdirection of burner flames. This can result in flame impingement of burners and heat exchang- ers causing failures.

BURNER FLAME

BURNER

MANIFOLD

A89020

Fig. 41ÐBurner Flame

TABLE 8ÐALTITUDE DERATE MULTIPLIER FOR U.S.A.

ALTITUDE	% OF	DERATE MULTIPLIER
(FT)	DERATE	FACTOR FOR U.S.A*
0Ð2000	0	1.00
2001Ð3000	4Ð6	0.95
3001Ð4000	6Ð8	0.93
4001Ð5000	8Ð10	0.91
5001Ð6000	10Ð12	0.89
6001Ð7000	12Ð14	0.87
7001Ð8000	14Ð16	0.85
8001Ð9000	16Ð18	0.83
9001Ð10,000	18Ð20	0.81

* Derate multiplier factor is based on midpoint altitude for altitude range.

CANADA

→At installation altitudes from 2000 to 4500 ft, this furnace must be derated 5% by an authorized Gas Conversion Station. To deter- mine correct input rate for altitude, see example above and use

0.95as derate multiplier factor.

a.Turn off all other gas appliances and pilots.

b.Start furnace and let operate for 3 minutes.

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