Service Manual

24
SYSTEM OPERATION
GAS PIPING CHECKS
Before placing unit in operation, leak test the unit and gas
connections.
WARNING
T
O AVOID THE POSSIBLITY OF EXPLOSION OR FIRE, NEVER USE A MATCH
OR OPEN FLAME TO TEST FOR LEAKS.
Check for leaks using an approved chloride-free soap and
water 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 piping system
before pressure testing the supply piping system with pres-
sures in excess of 1/2 psig (3.48 kPa). Isolate this unit from
the gas supply piping system by closing its external manual
gas shutoff valve before pressure testing supply piping sys-
tem with test pressures equal to or less than 1/2 psig (3.48
kPa).
PROPANE GAS TANKS AND PIPING
WARNING
PROPANE GAS IS HEAVIER THAN AIR AND ANY LEAKING GAS CAN SETTLE IN
ANY LOW AREAS OR CONFINED SPACES.
T
O PREVENT PROPERTY DAMAGE,
PERSONAL INJURY, OR DEATH DUE TO FIRE OR EXPLOSION CAUSED BY A
PROPANE GAS LEAK, INSTALL A GAS DETECTION WARNING DEVICE.
A gas detecting warning system is the only reliable way to
detect a propane gas leak. Iron oxide (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, please refer to the warning on this page.
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 liq-
uid, and “wetted surface” area of the container or con-
tainers.
2. Proper pressure regulation. (Two-stage regulation is rec-
ommended for both cost and efficiency).
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 appli-
ances.
Complete information regarding tank sizing for vaporization,
recommended regulator settings, and pipe sizing is avail-
able from most regulator manufacturers and propane gas
suppliers.
Refer to the following illustration for typical propane gas in-
stallations and piping.
200 PSIG
Maximum
5 to 15 PSIG
(20 PSIG Max.)
Continuous
11" W.C.
Second Stage
Regulator
First Stage
Regulator
Typical Propane Gas Installation
WARNING
I
F THE GAS FURNACE IS INSTALLED IN A BASEMENT, AN EXCAVATED
AREA OR A CONFINED SPACE, IT IS STRONGLY RECOMMENDED TO
CONTACT A PROPANE SUPPLIER TO INSTALL A GAS DETECTING
WARNING DEVICE IN CASE OF A GAS LEAK.
•
SINCE PROPANE GAS IS HEAVIER THAN AIR, ANY LEAKING GAS CAN
SETTLE IN ANY LOW AREAS OR CONFINED SPACES.
•
PROPANE GAS ODORANT MAY FADE, MAKING THE GAS UNDETECTABLE
EXCEPT WITH A WARNING DEVICE.
WARNING
AN UNDETECTED GAS LEAK WILL CREATE A DANGER OF EXPLOSION
OR FIRE. IF THE PRESENCE OF GAS IS SUSPECTED, FOLLOW THE
INSTRUCTIONS ON THE COVER OF THIS MANUAL. FAILURE TO DO SO
COULD RESULT IN SERIOUS PERSONAL INJURY OR DEATH.