Aerco INNOVATION INN1060, Руководство пользователя

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07/21/11 AERCO International, Inc.
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100 Oritani Dr.
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Blauvelt, NY 10913
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Ph: 800-526-0288 Page 143 of 200
GF-5030
Gas Supply Design Guide
TAG-0044_0A
General
AERCO Innovation Low NOx gas fired water heaters are modulating input devices that require an adequate volume of
natural gas at constant pressure for proper operation. The gas requirements specified in this document must be
satisfied to ensure efficient combustion. Designers and installers must adhere to the AERCO specifications and those
of the local authorities having jurisdiction. A thorough understanding and knowledge of these guidelines is required for
the successful design and installation of Innovation Low NOx series water heaters.
Gas Train Components
AERCO Innovation gas-fired water heaters are equipped with a standard UL approved/FM compliant gas trains. These
gas trains are factory tested and fired, with a minimum number of modular components. The gas train components
have been designed to operate at high combustion efficiencies by closely controlling both the volume and air/fuel
mixture to the burner. The major internal gas train components are:
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SAFETY SHUT OFF VALVE (SSOV) With BUILT-IN SUPPLY GAS REGULATOR - An electro-hydraulic gas valve,
containing a proof of closure switch, is utilized to stop fuel from flowing into the gas train of the heater. This is a 100%
tight shutoff device with a visible window indicator showing valve position. Reliable, and a standard industry
component, this valve is factory piped with a low gas pressure switch on the inlet side of the valve which monitors the
manifold pressure for minimum supply conditions. There is also a high gas pressure switch installed on the outlet side
of the gas valve, which shuts down the heater if gas manifold pressures exceed maximum conditions. The actuator
has a built-in regulator that replaces the need for an external supply regulator for installations that have supply
pressure of up to 14.0” W.C. For installations that have supply pressure greater than 14.0” W.C., see the
“Gas
Pressure Requirements ” section.
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AIR/FUEL VALVE - The air/fuel valve controls the volume and mixture of air and fuel in perfect proportion throughout
the entire modulation range of the heater. The valve utilizes one common shaft to simultaneously vary the gas port
area and air volume. The gas portion of the valve is a slide port type valve with linear proportion-to-position
characteristics. The air side uses a butterfly type valve for adjusting the air volume. The driver of the valve shaft is a
precision stepping motor which provides continuous positioning from full input to minimum fire. The air/fuel valve also
contains two proof-of-position switches.
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CAST ALUMINUM BLOWER ASSEMBLY - A cast aluminum pre-mix blower ensures the precise mixing of air and
fuel prior to entering the burner thereby providing controlled combustion.
* LOW NOx BURNER – The burner provides the actual point of air/fuel contact and combustion into the cylindrical
combustion/heat exchanger. Fabricated from metal fiber mesh covering a stainless steel body, the burner is stable
throughout the entire input range of the heater. The spark igniter and flame detector for the combustion supervision
system are part of this assembly. The burner is easily removable from the heater.
Gas Pressure Requirements
The AERCO Innovation Low NOx series heater requires a stable natural gas input pressure. The nominal inlet supply
pressure to the heater is 7.0” W.C. The allowable gas inlet pressure range is 4.0” W.C. (min.) to 14.0” W.C. (max.)
when firing at maximum input
. A low supply gas pressure switch in each gas train prevents the heater from operating
without sufficient pressure. Maximum allowable gas pressure is 14.0” W.C. Static gas pressure (when the unit is not
firing) may vary, however actual gas pressure should be measured when the unit is in operation (firing). Measure the
gas pressure with a manometer at the 1/8” NPT ball valve provided at the SSOV inlet. In a multiple heater installation,
gas pressure should initially be set for single heater operation, and then the remaining heaters should be staged on at
full fire, to insure gas pressures never fall below the minimum allowable pressure of 4.0” W.C.
An external isolation valve must be installed at each Innovation Low NOx heater, as shown in Diagram 1. This isolation
valve is supplied with the heater. For installations that have greater than 14.0” W.C. supply pressure, an external lock-
up type regulator must be installed downstream of the isolation valve. The lock-up type regulator(s) must be sized for
at least 1,000 cfh, but no more than 1,200 cfh, per heater. External gas regulators are self-contained with tapped
diaphragm vent ports allowing the diaphragm to change its position as required. These vents typically require piping to
the outside. For details, refer to the paragraph titled “
Venting of Gas Supply Regulators” on page 4 of this guide.
The SSOV/Regulator in the gas train is factory piped and does not require any vent piping.
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