Use and Care Manual

6-580.14

INSTALLATION - HIGH ALTITUDE ACCESSORY KIT

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

the values shown in Tables 11.1 and 11.2, use the following

equation to determine the appropriate manifold pressure for the

altitude and gas heating value being supplied.

Equation 12.1 - 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 11.1 or 11.2 (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 2-stage or modulating gas controls. No

adjustments to the low fire manifold pressure are necessary on

these units.