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
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,
NOTE:
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,
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.
Ð37Ð