AAON RZ Series, Установка, эксплуатация и обслуживание

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Both a gas pressure regulator and
overpressure protection device (OPD) shall
be installed if gas supply pressure to the unit
is greater than 2 psi (55.4” w.c.) and less than
5 psi (138.4” w.c.), in compliance with ANSI
Z21.80/CSA
6.22. For proper heater
operation, pressure to the regulator SHALL
NOT be greater than 5 psi (138.4” w.c.).
Piping Supports
Gas supply piping shall be supported directly
at the connection to the unit and at intervals
listed in the following table with metal straps,
blocks, or hooks. Piping shall not be strained
or bent.
Table 26 - Piping Support Intervals
Pipe Size
Support
Intervals
1/2” to 3/4”
Every 6 ft
3/4” to 1”
Every 8 ft
1-3/4” or Larger
(Horizontal)
Every 10 ft
1-1/4” or Larger (Vertical) Every Floor
Additional Gas Piping Considerations
Local codes will usually require a field
provided and installed manual main shutoff
valve and union external the unit. Main
shutoff valve shall be labeled. A field
provided 1/8” NPT pressure tap is required to
be installed in the piping just upstream of the
shutoff valve for test gage connection to
allow checking of the gas supply pressure at
the unit. A drip leg shall be installed near the
unit connection to trap sediment and
condensate. Pipe joint compounds used on all
gas piping connections shall be resistant to
liquid petroleum gases. If flexible gas piping
to the unit, or in the unit, must be replaced
connectors cannot be reused, only new
connectors may be used.
Heat exchanger comes equipped with a
condensate drain which shall be plumbed to
the appropriate drain according to the (United
States) National Fuel Gas Code ANSI-
Z223.1/NFPA 54 or the current (Canada)
National Fuel & Propane Installation Code
CSA B149.1 or B149.2, the International
Building Code, and any applicable local and
regional codes and regulations.
The condensate drain connection is located
next to the gas entry location. Each gas
heater has a silicone condensate drain
connected to it. The drains on each side of the
unit run into a common drain line which exits
the unit near the bottom of the heat access
doors.
AAON gas fired heat exchangers are
designed to be non-condensing. These heat
exchangers are mounted downstream of the
cooling coils. During the cooling season the
ambient air inside the heat exchanger tubes
can condense due to cold air being blown
over the outside of the tubes. The amount of
condensation will vary depending on the
ambient air temperature and humidity as well
as air temperature over the tubes. This
condensation can be drained onto the roof or
into any waste drain.
Typically during the heating season the heat
exchanger will not make any condensation.
However, short-cycling of the heater can
prevent the flue gases from reaching
temperatures above dew point (about 130⁰F)
which can cause condensation in the heat
exchanger.
Staged or modulated heat exchangers may
produce condensate depending on the firing
rate, ambient air temperature and humidity as
well as the percentage and temperature of
outside air being introduced to the unit. This
condensate is generally between a 2.9 and 4
pH level.
Condensation made in the heat exchanger
during the heating mode may need to be
managed and not just drained onto the roof