Counterflow Installations Gas Piping Checks; Piping - Goodman MH8 Installation Instructions Manual

A ground joint union, drip leg, and manual shutoff valve must
also be supplied by the installer. In some cases, the installer
may also need to supply a transition piece from 1/2" to another
pipe size.
When the gas piping enters through the left side of the furnace,
the installer must supply the following fittings (starting from the
gas valve):
• Straight pipe to reach the exterior of the furnace.
• A ground joint union, drip leg, and manual shutoff valve
must also be supplied by the installer. In some cases,
the installer may also need to supply a transition piece
from 1/2 inch to another pipe size.
C I
OUNTERFLOW NSTALLATIONS
When the gas piping enters through the left side of the furnace,
the installer must supply a straight pipe to reach the exterior of
the furnace.
A ground joint union, drip leg and manual shutoff valve must
also be supplied by the installer. In most cases, the installer
may also need to supply a transition piece from ½" to another
pipe size. When the gas piping enters through the right side of
the furnace, the installer must supply the following fittings (start-
ing at the gas valve):
• 90 Degree Elbow
• Close Nipple
• 90 Degree Elbow
• Straight Pipe to Reach Exterior of Furnace.
G P C
AS IPING HECKS
Before placing unit in operation, leak test the unit and gas con-
nections.
T
O AVOID THE POSSIBILITY OF
OR OPEN FLAME TO TEST FOR
Check for leaks using an approved chloride-free soap and wa-
ter solution, an electronic combustible gas detector, or other
approved testing methods.
NOTE: Never exceed specified pressures for testing. Higher
pressure may damage the gas valve and cause subsequent
overfiring, resulting in heat exchanger failure.
Disconnect this unit and shutoff valve from the gas supply pip-
ing system before pressure testing the supply piping system
with pressures in excess of 1/2 psig (3.48 kPa).
WARNING
,
EXPLOSION OR FIRE NEVER USE
.
LEAKS
This unit must be isolated from the gas supply system by clos-
ing its manual shutoff valve before pressure testing of gas sup-
ply piping system with test pressures equal to or less than 1/2
psig (3.48 kPa).
P G
ROPANE AS
I
F THE GAS FURNACE
AREA OR CONFINED
CONTACT A PROPANE
DEVICE IN CASE
S
•
INCE PROPANE
SETTLE IN ANY
P
•
ROPANE GAS
EXCEPT WITH
A gas detecting warning system is the only reliable way to
detect a propane gas leak. Rust can reduce the level of odorant
in propane gas. Do not rely on your sense of smell. Contact a
local propane gas supplier about installing a gas detecting
warning system. If the presence of gas is suspected, follow
the instructions on Page 3 of this manual.
All propane gas equipment must conform to the safety stan-
dards of the National Board of Fire Underwriters, NBFU Manual
58.
For satisfactory operation, propane gas pressure must be 10
inch WC at the furnace manifold with all gas appliances in
operation. Maintaining proper gas pressure depends on three
main factors:
1. Vaporization rate, depending on temperature of the liquid,
and "wetted surface" area of the container or containers.
2. Proper pressure regulation. (Two-stage regulation is
recommended for both cost and efficiency).
A MATCH
3. Pressure drop in lines between regulators, and between
second stage regulator and the appliance. Pipe size will
depend on length of pipe run and total load of all
appliances.
Complete information regarding tank sizing for vaporization, rec-
ommended regulator settings, and pipe sizing is available from
most regulator manufacturers and propane gas suppliers.
Since propane gas will quickly dissolve white lead and most
standard commercial compounds, special pipe dope must be
used. Shellac-based compounds resistant to the actions of
liquefied petroleum gases such as Gasolac
Clyde's ® or John Crane
Refer to the following illustration for typical propane gas instal-
lations and piping.
21
G S
AS UPPLY AND
T P
ANKS AND IPING
WARNING
IS INSTALLED IN A BASEMENT
,
SPACE IT IS STRONGLY RECOMMENDED
SUPPLIER TO INSTALL A GAS
.
OF A GAS LEAK
,
GAS IS HEAVIER THAN AIR ANY
LOW AREAS OR CONFINED SPACES
,
ODORANT MAY FADE MAKING
.
A WARNING DEVICE
® are satisfactory.
P
IPING
,
AN EXCAVATED
TO
DETECTING WARNING
LEAKING GAS CAN
.
THE GAS UNDETECTABLE
, Stalactic ,
® ®