Carrier 48VT(N) Check Heating Control, Check Gas Input, Adjust Gas Input, Burner Assembly

48VT-- A

Pipe Plug Manifold

A07679

Fig. 11 - Burner Assembly

BURNER FLAME

BURNER

MANIFOLD

C99021

Fig. 12 - Monoport Burner

Check Heating Control

Start and check the unit for proper heating control operation as follows (see furnace lighting instructions located on the inside of the control access panel):

1.Place room thermostat SYSTEM switch in the HEAT position and the fan switch is placed in AUTO position.

2.Set the heating temperature control of the thermostat above room temperature.

3.The induced-draft motor will start.

4.On a call for heating, the main burner should light within 5 sec. of the spark being energized. If the burners do not light, there is a 22-sec. delay before another 5-sec. try. If the burners still do not light, this sequence is repeated. If the burners do not light within 15 minutes from the initial call for heat, there is a lockout. To reset the control, break the 24-v power to W.

5.The evaporator fan will turn on 45 sec. after the flame has been established. The evaporator fan will turn off 45 sec. after the thermostat has been satisfied. Please note that the integrated gas unit controller (IGC) has the capability to automatically reduce the evaporator “ON” delay and in- crease the evaporator “OFF” delay in the event of high duct static and/or partially-clogged filter.

Check Gas Input

Check gas input and manifold pressure after unit start-up (See Table 3). If adjustment is required proceed as follows:

SThe rated gas inputs shown in Table 3 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 0.60

specific gravity, or propane gas with a heating value of 2500 Btu/ft3 at 1.5 specific gravity.

IN THE U.S.A.:

The input rating for altitudes above 2,000 ft (610 m) must be reduced by 4% for each 1,000 ft (305 m) above see 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 4 for correct input rate.

Table 4 – 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
(315---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
(2439	---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 to 4,500 ft (610 m to 1372 m) above sea level must be derated 10% by an authorized Gas Conversion Station or Dealer.

EXAMPLE:

90,000 Btu/hr Input Furnace Installed at 4300 ft (1311 m).

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

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.

!CAUTION

UNIT DAMAGE HAZARD

Failure to follow this caution may result in reduced unit and/or component life.

Do Not redrill an orifice. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive burner noise and misdirection of burner flame. If orifice hole appears damaged or it is suspected to have been redrilled, check orifice hole with a numbered drill bit of correct size.

Adjust Gas Input

The gas input to the unit is determined by measuring the gas flow at the meter or by measuring the manifold pressure. Measuring the gas flow at the meter is recommended for natural gas units. The manifold pressure must be measured to determine the input of propane gas units.

Measure Gas Flow (Natural Gas Units)

Minor adjustment to the gas flow can be made by changing the manifold pressure. The manifold pressure must be maintained between 3.2 and 3.8 IN. W.C.

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