Installation and Service Manual

6-561.10

INSTALLATION - HIGH ALTITUDE ACCESSORY KIT

If the heating value of the gas being supplied is different than the values

shown in Tables 12.1 and 12.2, use the following equation to determine the

appropriate manifold pressure for the altitude and gas heating value being

supplied.

Equation 13.1 - Manifold Pressure for Derated Gas

WHERE:

ACT

= Manifold Pressure (in. W.C.) at Altitude –

Manifold pressure setting for the heater being

installed

BTU

TBL

= BTU/ft

Content of Gas –

Obtained from Tables 12.1 or 12.2 (whichever is

applicable)

BTU

ACT

= BTU/ft

Content of Gas –

Obtained from the local utility company

= Manifold Pressure (in. W.C.), at Sea Level –

Use 3.5" W.C. for natural gas and 10.0" W.C. for

propane gas

NOTE: Only the primary manifold pressure should be adjusted

on units equipped with two-stage or modulating gas controls.

No adjustments to the lowf fire manifold pressure are necessary

on these units.