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P
G
T
P
ROPANE
AS
ANKS AND
I
F THE GAS FURNACE IS INSTALLED IN A BASEMENT
,
AREA OR CONFINED SPACE
IT IS STRONGLY RECOMMENDED TO
CONTACT A PROPANE SUPPLIER TO INSTALL A GAS DETECTING WARNING
DEVICE IN CASE OF A GAS LEAK
S
•
INCE PROPANE GAS IS HEAVIER THAN AIR
SETTLE IN ANY LOW AREAS OR CONFINED SPACES
P
•
ROPANE GAS ODORANT MAY FADE
EXCEPT WITH A WARNING DEVICE
A gas detecting warning system is the only reliable way to detect
a propane gas leak. Rust can reduce the level of odorant in pro-
pane 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 instruc-
tions listed in the Safety Considerations section of this manual.
All propane gas equipment must conform to the safety standards
of the National Board of Fire Underwriters, NBFU Manual 58.
For satisfactory operation, propane gas pressure must be 10"
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).
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,
recommended 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 stan-
dard commercial compounds, special pipe dope must be used.
Always use a pipe thread sealant approved for all gases.
Refer to the this illustration for typical propane gas installations
and piping.
First Stage
Regulator
200 PSIG
Maximum
Propane Gas Installation (Typ.)
IPING
WARNING
,
AN EXCAVATED
.
,
ANY LEAKING GAS CAN
.
,
MAKING THE GAS UNDETECTABLE
.
5 to 15 PSIG
(20 PSIG Max.)
Continuous
11" W.C.
Second Stage
Regulator
Figure 35
C
A
& F
IRCULATING
IR
D
- A
F
UCT WORK
IR
LOW
Duct systems and register sizes must be properly designed for
the CFM and external static pressure rating of the furnace. De-
sign the ductwork in accordance with the recommended meth-
ods of "Air Conditioning Contractors of America" Manual D.
Install the duct system in accordance with Standards of the Na-
tional Board of Fire Underwriters for the Installation of Air Condi-
tioning, Warm Air Heating and Ventilating Systems. Pamphlets
No. 90A and 90B.
A closed return duct system must be used, with the return duct
connected to the furnace. NOTE: Ductwork must never be at-
tached to the back of the furnace. For upflow installations re-
quiring 1800 CFM or more, use either two side returns or bottom
return or a combination of side /bottom. Flexible joints may be
used for supply and return connections to reduce noise transmis-
sion. To prevent the blower from interfering with combustion air
or draft when a central return is used, a connecting duct must be
installed between the unit and the utility room wall. Never use a
room, closet, or alcove as a return air chamber.
C
D
S
HECKING
UCT
TATIC
Refer to your furnace rating plate for the maximum ESP (ex-
ternal duct static) rating.
N
EVER ALLOW THE PRODUCTS OF COMBUSTION
,
MONOXIDE
TO ENTER THE RETURN DUCT WORK OR CIRCULATION AIR
.
SUPPLY
Total external static refers to everything external to the fur-
nace cabinet. Cooling coils, filters, ducts, grilles, registers
must all be considered when reading your total external static
pressure. The supply duct pressure must be read between
the furnace and the cooling coil. This reading is usually taken
by removing the "A" shaped block off plate from the end on
the coil; drilling a test hole in it and reinstalling the block off
plate. Take a duct static reading at the test hole. Tape up
the test hole after your test is complete. The negative pres-
sure must be read between the filter and the furnace blower.
Too much external static pressure will result in insufficient
air that can cause excessive temperature rise. This can cause
limit switch tripping and heat exchanger failure.
29
ILTERS
WARNING
,
INCLUDING CARBON
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