Bryant 355M-40-5, 355M-40-4 operating instructions Ðaltitude Derate Multiplier for U.S.A, Canada

BURNER

ORIFICE

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. 49ÐBurner Flame

At altitudes above 2000 ft, this furnace has been ap- proved for a 2 percent derate for each 1000 ft above sea level. See Table 13 for derate multiplier factor and example.

TABLE 13ÐALTITUDE 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.

EXAMPLE:

100,000 Btuh input furnace installed at 4300 ft.

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

CANADA

At installation altitudes from 2000 to 4500 ft, this furnace must be derated 5 percent by an authorized Gas Conversion Station or Dealer. To determine correct input rate for altitude, see example above and use 0.95 as derate multiplier factor.

b. Reinstall burner box cover.

NOTE: Clocking gas input rate MUST always be performed with the burner box cover INSTALLED.

c. Check that gas valve adjustment caps are in place for proper input to be clocked.

d. Obtain yearly heat value average for local gas supply.

NOTE: Be sure heating value of gas used for calculations is correct for your altitude. Consult local gas utility for altitude adjustment of gas heating value.

e. Check and verify orifice size in furnace. NEVER AS-

SUME THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.

f.Turn off all other gas appliances and pilots.

g.Turn setup switch SW-2 to ON position. (See Fig. 25.) This keeps furnace locked in low-heat operation.

h.Let furnace run for 3 minutes in low-heat operation.

i.Measure time (in sec) for gas meter to complete 1 revolution. Note reading.

j.Refer to Table 14 for cubic ft of gas per hr.

k.Multiply gas rate cu ft/hr by heating value (Btu/cu ft).

l.Turn setup switch SW-2 to OFF position and jumper R and W2 thermostat connections. (See Fig. 25.) This keeps furnace locked in high-heat operation. Repeat items h through k for high-heat operation.

EXAMPLE: (High-heat operation at 0Ð2000 ft altitude) Furnace input from rating plate is 100,000 Btuh

Btu heating input = Btu/cu ft X cu ft/hr Heating value of gas = 975 Btu/cu ft

Time for 1 revolution of 2-cu ft dial = 70 sec Gas rate = 103 cu ft/hr (from Table 14)

Btu heating input = 103 X 975 = 100,425 Btuh In this example, the orifice size and manifold pressure adjustment is within ±2 percent of the furnace input rate.

NOTE: Measured gas inputs (high heat and low heat) must be within ±2 percent of that stated on furnace rating plate when installed at sea level or derated per that stated above when installed at higher altitudes.

m.Remove jumper across R, W/W1, and W2 thermostat connections to terminate call for heat.

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