Setting Gas Pressure; Supply Gas Pressure Measurement; Manifold Gas Pressure Measurement - Rheem 801T Series Installation Instructions Manual

GAS SUPPLY (cont .)

SETTING GAS PRESSURE

The maximum gas supply pressure to the furnace must
not exceed 10.5" w.c. natural gas, or 13" w.c. LP gas. The
minimum supply gas pressure to the gas valve should be 59 w .c .
natural gas or 119 w .c . LP gas . A properly calibrated manometer
is required for accurate gas pressure measurements .
SUPPLY GAS PRESSURE
MEASUREMENT
An inlet pressure tap is on the input side of the gas valve .
1 . With gas shut off to the furnace at the manual gas valve
outside the unit, remove the inlet pressure tap plug .
2 . Connect a manometer to the pressure tap .
3 . Turn on the gas supply and operate the furnace and all
other gas-fired units on the same gas line as the furnace .
4 . Note or adjust the line gas pressure to give:
A . 59 - 10 .59 w .c . for natural gas .
B . 119 - 139 w .c . for LP gas .
5 . Shut off the gas at the manual gas valve and remove the
manometer and hose .
6 . Replace the pressure tap plug before turning on the gas .
7 . Turn on the gas supply and check for gas leaks using an
approved leak detector . Do NOT use a flame of any kind to
check for leaks . Repair any leaks and repeat .
If the supply gas line pressure is above these ranges,a high
pressure in line gas regulator may be required . Consult local
gas utility . With LP gas, have the LP supplier reduce the line
pressure at the regulator .
If supply gas line pressure is below these ranges, either remove
any restrictions in the gas supply piping or enlarge the gas pipe .
See Tables 6 and 7 . With LP gas, have the LP supplier adjust
the line pressure at the regulator .
26
CAUTION
!
ELEVATIONS ABOVE 2000 FT . REQUIRE THAT THE FUR-
NACE INPUT RATING BE ADJUSTED AND THAT THE
SIZE OF THE BURNER ORIFICES BE RECALCULATED
BASED ON ELEVATION AND GAS HEATING VALUE . THE
BURNER ORIFICES MAY (OR MAY NOT) NEED TO BE
CHANGED . SEE THE SECTION TITLED "HIGH ALTITUDE
INSTALLATIONS" OF THIS BOOK FOR INSTRUCTIONS .
MANIFOLD GAS PRESSURE
MEASUREMENT
Natural gas manifold pressure should be 3 .5" (± .3) w .c . LP
gas manifold pressure should be 10 .0" (± .5) w .c . Only small
variations in gas pressure should be made by adjusting the
pressure regulator .
1 . With the gas to the unit shut off at the manual gas valve,
remove the outlet pressure tap plug .
2 . Connect a manometer to this pressure tap .
3 . Turn on the gas supply and operate the furnace (apply a
heat call) .
4 . Note or adjust the manifold gas pressure to give:
A . 3 .59 (± .3) w .c . for natural gas .
B . 10 .09 (± .5) w .c . for LP gas .
5 . To adjust the pressure regulator, remove the regulator cap .
(See Figures 20A and 20B .)
6 . Turn the adjustment screw clockwise to increase pressure,
or counterclockwise to decrease pressure .
7 . Securely replace the regulator cap .
8 . Shut off gas at the manual gas valve and remove the ma-
nometer and hose .
9 . Replace the pressure tap plug before turning on the gas .
10 . Turn on the gas supply and apply a heat call to the furnace
then check for gas leaks using an approved leak detector .
Do NOT use a flame of any kind to check for leaks . Repair
any leaks and repeat .