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For satisfactory operation, propane gas pressure must be 11 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).
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
standard commercial compounds, special pipe dope must be used.
Shellac-based compounds resistant to the actions of liquefied
petroleum gases such as Gasolac
®
Crane
are satisfactory.
Refer to the following illustration for typical propane gas installations
and piping.
First Stage
Regulator
200 PSIG
Maximum
Propane Gas Installation (Typ.)
P
G
P
C
ROPANE
AS
IPING
HARTS
Sizing Between First and Second Stage Regulator*
Maximum Propane Capacities listed are based on 2 psig pressure drop at 10 psig setting.
Capacities in 1,000 BTU/hour.
Pipe or
Tubing
Tubing Size, O.D. Type L
Length,
3/8"
1/2"
Feet
10
730
1,700
3,200
20
500
1,100
2,200
30
400
920
2,000
40
370
850
1,700
50
330
770
1,500
60
300
700
1,300
80
260
610
1,200
100
220
540
1,000
125
200
490
150
190
430
175
170
400
200
160
380
To convert to capacities at 15 psig settings - multiply by 1.130
To convert to capacities at 5 psig settings - multiply by 0.879
IO-247A
®
, Stalactic
®
, Clyde's
5 to 15 PSIG
(20 PSIG Max.)
Continuous
11" W.C.
Second Stage
Regulator
Nominal Pipe Size
Schedule 40
5/8"
3/4"
7/8"
1/2"
5,300
8,300
3,200
3,700
5,800
2,200
2,900
4,700
1,800
2,700
4,100
1,600
2,400
3,700
1,500
2,200
3,300
1,300
1,900
2,900
1,200
1,700
2,600
1,000
900
1,400
2,300
900
830
1,300
2,100
830
780
1,200
1,900
770
730
1,100
1,800
720
Sizing Between Single or Second Stage Regulator and Appliance*
Maximum Propane Capacities Listed are Based on 1/2" W.C. pressure drop at 11" W.C. setting.
Capacities in 1,000 BTU/hour.
Pipe or
Tubing
Length,
3/8"
1/2"
Feet
10
39
92
20
26
62
30
21
50
40
19
41
50
18
37
60
16
35
80
13
29
100
11
26
125
10
24
150
9
21
200
8
19
250
8
17
*Data in accordance with NFPA pamphlet NO. 54
X. CIRCULATING AIR AND FILTERS
D
- A
UCTWORK
®
or John
F
L O W
N
EVER ALLOW THE PRODUCTS OF COMBUSTION, INCLUDING CARBON
MONOXIDE, TO ENTER THE RETURN DUCTWORK OR CIRCULATION AIR SUPPLY.
Duct systems and register sizes must be properly designed for the
CFM and external static pressure rating of the furnace. Ductwork
should be designed in accordance with the recommended methods
of "Air Conditioning Contractors of America" Manual D.
A duct system must be installed in accordance with Standards of
the National Board of Fire Underwriters for the Installation of Air
Conditioning, 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 attached
to the back of the furnace. Supply and return connections to the
furnace may be made with flexible joints to reduce noise
transmission. 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. A room,
closet, or alcove must not be used as a return air chamber.
When the furnace is used in connection with a cooling unit, the
furnace should be installed in parallel with or on the upstream side
of the cooling unit to avoid condensation in the heating element.
3/4"
With a parallel flow arrangement, the dampers or other means used
to control the flow of air must be adequate to prevent chilled air
7,500
4,200
from entering the furnace and, if manually operated, must be
4,000
equipped with means to prevent operation of either unit unless the
3,700
damper is in the full heat or cool position.
3,400
3,100
When the furnace is installed without a cooling coil, it is
2,600
recommended that a removable access panel be provided in the
2,300
outlet air duct. This opening shall be accessible when the furnace
2,100
1,900
is installed and shall be of such a size that the heat exchanger can
1,700
be viewed for visual light inspection or such that a sampling probe
1,500
can be inserted into the airstream. The access panel must be made
to prevent air leaks when the furnace is in operation.
When the furnace is heating, the temperature of the return air
entering the furnace must be between 55°F and 100°F.
When a furnace is installed so that supply ducts carry air circulated
by the furnace to areas outside the space containing the furnace,
the return air shall also be handled by a duct sealed to the furnace
casing and terminating outside the space containing the furnace.
20
Tubing Size, O.D. Type L
5/8"
3/4"
7/8"
1-1/8"
1/2"
199
329
501
935
275
131
216
346
630
189
107
181
277
500
152
90
145
233
427
129
79
131
198
376
114
72
121
187
340
103
62
104
155
289
89
55
90
138
255
78
48
81
122
224
69
43
72
109
202
63
39
66
100
187
54
36
60
93
172
48
IR
WARNING
Nominal Pipe Size
Schedule 40
3/4"
1"
1-1/4" 1-1/2"
567
1,071 2,205 3,307
393
732
1,496 2,299
315
590
1,212 1,858
267
504
1,039 1,559
237
448
913
1,417
217
409
834
1,275
185
346
724
1,066
162
307
630
976
146
275
567
866
132
252
511
787
112
209
439
665
100
185
390
590
12/04
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