Installation, Operation & Maintenance Manual
IM-895
5
Follow proper handling instructions as given earlier.
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 the unit 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 guides, 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.
Do not use pipe sizes smaller than 1/2".
3. Pipe size to the unit must match the factory side access
gas connection size, 1" NPT.
4. Install a ground joint union with brass seat and a manual
shut-off valve external to the unit casing, as shown in
Figure 7.1, adjacent to the unit for emergency shut-off
and easy servicing of controls. Include a 1/8" NPT plugged
tapping accessible for test gauge connections.
5. Provide a sediment trap, as shown in Figure 7.1, before
each unit and where low spots in the pipeline cannot be
avoided.
6. This unit requires a constant minimum gas supply pressure,
6.5" w.c., when the unit is operating at maximum gas flow.
If the gas supply pressure exceeds 1 psig, a gas pressure
regulator must be installed before the unit to prevent
damage to the internal valve components. If the pressure
is lower than 6.5" w.c., the heater may not perform to
specifications.
7. Support piping so that no strains are imposed on the unit
controls when connected.
Unit Installation
(Gas Connections)
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 rating plate. The unit and its individual shutoff valve(s)
must be disconnected from the gas supply during any test pressure more than 0.5 psig (3.5 kPa).
3. For test pressure less than 0.5 psig (3.5 kPa), the unit gas control must be isolated from the supply gas piping by closing the unit manual
shutoff valve(s).
4. For an indoor unit, where required by Code, use a dedicated line for venting gas to the outside of the building.
WARNING
1. 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.
2. Do not operate unit with a gas input rate greater than that
shown on the unit rating plate.
3. A Model ADH cannot substitute for make-up air. If severe
negative pressure exists because of exhaust loads, make-up
air must be provided for the ADH to operate properly.
CAUTION
8. Blow out the gas line to remove debris before making
connections.
9. Purge the gas line to remove air before attempting to start
unit. Purging of air from gas lines should be performed as
described in ANSI Z223.1-latest edition "National Fuel Gas
Code" or in Canada in CAN/CGA-B149.
10. All field gas piping must be pressure/leak tested prior
to unit operation. Use a non-corrosive bubble forming
solution or equivalent for leak testing. The heater and
its individual shut-off valve must be disconnected from
the gas supply piping system during any pressure testing
of that system at test pressures more than 0.5 psig. The
heater must be isolated from the gas supply piping system
by closing its individual manual shutoff valve during any
pressure testing of the gas supply piping system at test
pressures equal to or less than 0.5 psig.
11. Weatherize all utility clearance holes on the unit after
connections have been made.
Figure 7.1. Required Piping to Unit Gas Controls
GAS
SUPPLY LINE
GROUND
JOINT
UNION
W/ BRASS
SEAT
GAS
SUPPLY LINE
MANUAL GAS
SHUT-OFF VALVE
TO
CONTROLS
3 "
MIN.
PLUGGED
1 /8" NPT TEST
GAGE CONNECTION
SEDIMENT
TRAP
Manual gas shut-off valve is in
the "off" position when handle
is perpendicular to pipe.