AERCO Modulex High Pressure Manual - Manual (Page 9)

INSTALLATION, OPERATION & MAINTENANCE
1-1
1
GENERAL DESCRIPTION
IMPORTANT
Each AERCO Modulex Boiler is shipped as either a Natural Gas Only Boiler OR
a Propane Gas Only Boiler. It Is Not a Dual-Fuel Boiler. Ensure that the correct
fuel and fuel pressure are used when operating the equipment.
1.1 – TECHNICAL FEATURES
Modulex is a compact, modular, gas fired, Low NOx, condensing boiler. The boiler body, is comprised
of sections of cast aluminum/magnesium/silicon alloy. The boiler is designed to recover the sensible
and the latent heat of the combustion gases, thereby allowing it to attain a thermal efficiency of 92% as
tested by the Hydronics Institute, a Division of GAMA. These cast aluminum sections make up modules
referred to as the heat modules. Each module can deliver an output between a maximum of 152 MBH
and a minimum of 45 MBH and are composed of a pre mix combustion chamber, metallic mesh radiant
burner, modulating fan with control pressure switch, gas valve, ignition device, flame detection, NTC
sensor for local temperature control and a safety thermostat.
The heat modules are housed in a single enclosure and are connected to a single exhaust manifold.
These modules are independent of each and are sequentially staged, known as cascading, to take
advantage of higher efficiencies. Each heat module has its own printed circuit (PC) board that controls
and monitors combustion as well as the temperature of each heat module providing operational safety.
The entire boiler is controlled by a single microprocessor. This microprocessor is responsible for the
staging and modulation of the heat modules, monitoring supply and return water temperatures as well
as heating and domestic hot water (DHW) zones. Other features include:
• The heating load is shared with as many boiler modules as possible running at a minimum
output to ensure the maximum efficiency at partial load operation.
• Access to all testing/programming parameters of each module: operation test, operation time,
boiler freeze protection from 45°F (7°C), pump’s anti seize program.
• Lead-lag burner operation based on burner operating hours. The boiler module with the least
burner operating hours is the first to start and the burner with the most operating hours is the
first to stop.
• D.H.W. production by a priority sensor, with control capability of a dedicated pump or a 3-way
diverting valve for storage tank temperature control.
• A service mode for manual operation of individual heat modules capability for troubleshooting
or combustion calibration
• Diagnostics including relay and sensor testing.
Reliability is improved by the modular design of the Modulex since each heat module is independent of
the other, having its own ignition and combustion safeguard system. If one of the boiler’s heat modules
stops functioning, the remaining module(s) continue to operate.
The Modulex boiler can be comprised of from 2 to 7 modules and 3 to 8 cast aluminum sections. The
input to each heat module is 151.5 MBTU/Hr. The smallest Modulex 303, comprised of two heat
modules, has a combined total input of 303,000 BTU/Hr (2 x 151.5 = 303 MBTU) while the largest, the
1060 comprised of 7 heat modules has a total input of 1060 MBTU’s (See Table 1-1).
For one Modulex 303 boiler consisting of two modules, the output modulates from 15% to 100%. For a
Modulex 1060 boiler consisting of seven modules, the output modulates from 4.3% and 100%. If a
system comprised of two boilers is installed, then the modulation range for each boiler increases to 7.5%
to 100% for the Modulex 303 and 2.2% to 100% for the Modulex 1060.