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unit installation
unit installation
1. Follow site preparation instructions for applicable curb, rail,
or slab mounting. Check the rating plate of the unit before
lifting to insure that the model number shown matches that
shown on the plans. Although units may look similar, their
function, capacities, options, and accessories may vary
widely. Check unit dimensions for proper fit.
2. If the unit is mounted on a factory-supplied curb:
a. Install roof curb using previous roof curb instructions (page 6).
b. Thoroughly clean and dry the top of the curb surface.
c. Attach the factory-supplied curb gasket around the top
perimeter of the curb.
d. Lift the unit into place and set the unit down evenly on curb.
e. If units are supplied with accessories for field-mounting,
attach all accessories after the unit has been put into place.
f. Make final unit connections to the electric power supply and
remote control circuits. Connect gas lines. Caulk all utility
clearance holes on the unit after connections have been made.
3. If the unit is to be rail or slab-mounted, follow directions
listed on pages 4 and 5.
4. Do not modify or block combustion or ventilation openings.
5. Units require field-support of the accessory inlet hood. Be
sure that the accessory hood is properly supported. (See
Unit and Accessory Drawings on pages 34-39).
6. Some models may be split-shipped to accommodate
maximum shipping widths. When assembling unit sections,
make sure that the sections are properly gasketed, caulked,
and secured before operating the equipment.
Gas connections
W arninG
1. All field gas supply lines should be pressure/leak tested
prior to operation. Never use an open flame. Use a soap
solution or equivalent for testing.
2. Gas pressure to the unit controls must never exceed the
pressure shown on the unit's rating plate. The unit and its
individual shutoff valve(s) must be disconnected from the
gas supply during any test pressure in excess of 1/2 psig
(3.5 kPa).
3. For test pressure less than 1/2 psig (3.5 kPa), the unit's
gas control must be isolated from the supply gas piping
by closing the unit's manual shutoff valve(s).
caution
Purging of air from gas supply lines should be performed as
described in ANSI Z223.1 - latest edition "National Fuel Gas
Code", or in Canada in CAN/CGA-B149 codes.
1. Installation of piping must be in accordance with local codes,
and ANSI Z223.1-latest edition, "National Fuel Gas Codes".
(In Canada CAN/CGA-B149 Code.)
2. Piping to units must conform to local and national
requirements for type and volume of gas handled, and
pressure drop allowed in the line. Refer to the unit rating
plate to determine the Btu capacity of the unit and the type of
gas the unit is designed to use. Using this information, refer
to the ASHRAE Guide Fundamentals Handbook, or other gas
pipe sizing guide, to determine the correct supply pipe size.
Allow sufficient pipe size based on allowable pressure drop
in supply line. Where several units are served by the same
main, the total capacity of all the units served by the main
must be used. Avoid pipe sizes smaller than 1/2".
8
8
3. After threading and reaming the ends, inspect piping and
remove loose dirt and chips.
4. Support piping so that no strains are imposed on the unit
controls.
5. Use two wrenches when connecting field piping to units.
6. Provide a drip pocket before each unit and in the line where
low spots cannot be avoided. (See Figure 8.1).
7. Take-off to unit should come from top or side of main to
avoid trapping condensate.
8. Piping subject to wide temperature variations should be
insulated.
9. Pitch piping at least 1/4" per 15 feet of horizontal run.
10. Compounds used on threaded joints of gas piping must be
resistant to action of liquefied petroleum gases.
11. Purge air from gas supply lines.
12. After air has been purged, check for gas leaks in the piping
systems using a soap/water solution.
13. Install a ground joint union and gas cock external to the
unit for easy servicing of controls, including a 1/8" NPT
plugged tapping accessible for test gauge connections
(see Figure 8.1).
14. Allow at least 5 feet of piping between any high pressure
regulator and the unit control string.
Standard field gas supply connection sizes are shown in Table 8.1.
Figure 8.1 - required Piping to unit's Gas controls
GAS
SUPPLY LINE
GAS
SUPPLY LINE
3"
MIN.
SEDIMENT
TRAP
Manual gas shut-off valve is in the "off" position when handle is
j
perpendicular to pipe.
table 8.1 - Field Gas supply connections
mBh
8-14" W.c.
digit 9-12
digit 13=a
275-400
3/4"
550-720
1"
825
1-1/4"
1000
1-1/4"
1100
1-1/4"
1375
1-1/2"
1650
2"
1925-2200
2"
2475
2-1/2"
2750-3575
2-1/2"
3850-4950
n/a
5225-7425
n/a
7-500.10
GROUND
JOINT
UNION
W/ BRASS
j
SEAT
MANUAL GAS
SHUT-OFF VALVE
TO
CONTROLS
PLUGGED
1/8" NPT TEST
GAGE CONNECTION
natural
Propane
1-5 psig
11-14" W.c.
digit 13=B
digit 13=c
n/a
3/4"
n/a
1"
1"
1"
1"
1"
1-1/4"
1-1/4"
1-1/4"
1-1/4"
1-1/4"
1-1/2"
1-1/2"
2"
1-1/2"
2"
2"
2"
2"
n/a
2-1/2"
n/a
1-5 psig
digit 13=d
n/a
n/a
3/4"
1"
1"
1"
1-1/4"
1-1/4"
1-1/4"
1-1/2"
2"
n/a
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