Carrier 58TMA Altitude Derate Multiplier for U.S.A, United States, Example, Canada

BURNER

ORIFICE

A93059

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 exchangers, causing failures.

e.Move setup switch SW-2 to OFF position after completing low-heat adjustment.

f.Jumper R and W2 thermostat connections on control center. (See Fig. 14.) This keeps furnace locked in high-heat operation.

g.Turn high-heat adjusting screw (5/64 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise (in) to increase rate.

NOTE: DO NOT set high-heat 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.

h.When correct input is obtained, replace caps that conceal gas valve regulator adjustment screws. Main burner flame should be clear blue, almost transparent. (See Fig. 20.)

i.Remove jumper R to W2.

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

a.Calculate high-altitude adjustment (if required).

UNITED STATES

At altitudes above 2000 ft, this furnace has been approved for a 4 percent derate for each 1000 ft above sea level. See Table 9 for derate multiplier factor and example.

Table 9—Altitude Derate Multiplier for U.S.A.

ALTITUDE	% OF	DERATE MULTIPLIER
(FT)	DERATE	FACTOR FOR U.S.A.*
0—2000	0	1.00
2001—3000	8—12	0.90
3001—4000	12—16	0.86
4001—5000	16—20	0.82
5001—6000	20—24	0.78
6001—7000	24—28	0.74
7001—8000	18—32	0.70
8001—9000	32—36	0.66
9001—10,000	36—40	0.62

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

EXAMPLE:

85,000 Btuh input furnace installed at 4300 ft.

Furnace Input		Derate		Furnace Input Rate
Rate at	X	Multiplier	=	at Installation
Sea Level		Factor		Altitude
85,000	X	0.82	=	69,700

CANADA

At installation altitudes from 2000 to 4500 ft, this furnace must be derated 10 percent by an authorized Gas Conver- sion Station or Dealer. To determine correct input rate for altitude, see example above and use 0.82 as derate multi- plier factor.

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

c. 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.

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

SUME THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.

e.Turn off all other gas appliances and pilots.

f.Move setup switch SW-2 to ON position. (See Fig. 17.) This keeps furnace locked in low-heat operation.

g.Jumper R to W/W1.

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

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

j.Refer to Table 10 for cubic ft of gas per hr.

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

l.Move setup switch SW-2 to OFF position and jumper R and W2 thermostat connections. (See Fig. 17.) This keeps furnace locked in high-heat operation. Repeat items h through k for high-heat operation.

EXAMPLE: (High-heat operation at 0—2000 ft altitude) Furnace input from rating plate is 85,000 Btuh

Btu heating input = Btu/cu ft X cu ft/hr Heating value of gas = 1050 Btu/cu ft Time for 1 revolution of 2-cu ft dial = 92 sec Gas rate = 80 cu ft/hr (from Table 10)

Btu heating input = 80 X 1050 = 84,000 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.

5.Set temperature rise.

Place SW-2 in ON position. Jumper R to W/W1 and W2 to check high-gas-heat temperature rise. To check low-gas-heat temperature rise, remove jumper to W2. Determine air tem- perature rise for both high and low heat using the following steps. DO NOT exceed temperature rise ranges specified on unit rating plate for high and low heat.

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