IOM GMI 2M & 2ML Nov 2010.doc
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cam mechanism) allows for throttling of the air/gas mixture flowing into the Riello burner. For as
long as the set temperature is above that of the outlet water, the boiler/water heater operates at
maximum output capacity. Analogue output signals from the temperature sensor are sent to the
temperature controller, which in turn sends corresponding signals to the servomotor. This throttles
the flow of gas and combustion air in the gas butterfly valve and the air damper. Therefore, the
appropriate volume of air/gas mixture flows into the burner, allowing for almost perfect air/gas
mass, and volume ratios. As the outlet temperature approaches the set temperature, the air/gas
mixture flow is gradually reduced by the servomotor (connected to the gas butterfly valve and the
air damper). This results in the corresponding gradual decrease in the unit’s capacity. Thus the
throttle system allows for optimum continuous operation of the boiler, significantly reducing
on/off cycles. The said system offers the user almost infinite modulating capacity within the
boiler/water heater operating range.
1.3
Safety Features
Each Gasmaster GMI 2M boiler and water heater is equipped with a number of safety features.
I:
Low Water Cut-Off Switch:
One “McDonnell & Miller” low water cut-off switch
is installed on the outlet manifold. When water reaches the LWCO position, the
burner should fire.
II:
Flame Sensor:
A Riello flame probe is used as a flame proving sensor. This is
connected to the burner controller, and is installed inside the burner head. At any
time after the main gas valve is opened, if flame is not detected for a period longer
than 4 seconds, the burner controller will be deactivated and the main gas valve will
immediately close.
III:
High Temperature Limit:
Each unit is equipped with a “Honeywell” high
temperature limit switch. If outlet water temperature exceeds the temperature set
on this switch, the burner controller will be deactivated and the gas valves will
immediately close.
IV:
Air Pressure Switch:
One low air pressure switch is installed on the side of the
blower and measures air pressure entering the burner (for exact location of the
switch please see item #5 on the drawing presented on page 4 of the Riello
catalogue). If the combustion air pressure drops by more than 20% below the
nominal air pressure (minimum pressure of 0.4” wc), the burner controller will be
deactivated and the main gas valve will immediately close.
V: Relief
Valve:
A “Conbraco” safety relief valve with prescribed nominal pipe size
of 1 1/4”valve inlet/outlet, and minimum relief capacity of 4,974,000 Btu/hr and
150 psig relief pressure, is installed on the water outlet manifold and supplied as
standard equipment. When the boiler or water heater is used in heating applications
having working pressures in the range 40–160 psig, an appropriate pressure relief
valve should be installed.
Summary of Contents for GMI 2M
Page 6: ...IOM GMI 2M 2ML Nov 2010 doc 6 SECTION 1 INTRODUCTION...
Page 13: ...IOM GMI 2M 2ML Nov 2010 doc 13 SECTION 2 INSTALLATION...
Page 22: ...IOM GMI 2M 2ML Nov 2010 doc 22 SECTION 3 OPERATION...
Page 30: ...IOM GMI 2M 2ML Nov 2010 doc 30 SECTION 4 MAINTENANCE...
Page 34: ...IOM GMI 2M 2ML Nov 2010 doc 34...
Page 35: ...IOM GMI 2M 2ML Nov 2010 doc 35 START UP REPORT...