2) The burner shall be capable of infinitely modulating between 25% and 100% fire (4:1 turndown) with smooth starts and clean combustion. Boiler Controls: 1) All electrical boiler functions shall be controlled, operated, and monitored by a microprocessor-based control. 2) The microprocessor shall control and modulate the burner based on current system output requirements to maintain the boiler set point temperature and be accurate to within plus or minus 1°F. 3) The hot surface ignition system s

WC, and is self-adjusting for altitudes up to 6,000 feet all while providing low NOx emissions that meet or exceed the most stringent standards Heavy-duty ASME 160 psi copper finned tube heat exchanger—Vertical, straight tube, multi-pass design surrounds the burner with a 360° wall of copper finned tubing, making the entire heat exchanger immune to thermal shock The sealed heat exchanger flue collection system is constructed of AL29-4C stainless steel that is immune to corrosive flue gases C D B

When desired adjustments are complete, reinstall the cap on the gas valve. CO readings should be less than 200 ppm. Start Up Note: There will be a time delay between adjustments on the gas valve and the response of the CO2 measuring instrument. Adjust the settings in small increments and allow the combustion readings to stabilize for at least 3 minutes before readjusting. High Fire CO2 Settings NATURAL GAS 8.5 - 9.0% CO2 PROPANE GAS 9.5 - 10.5% CO2 Low Fire CO2 Settings NATURAL GAS 6.5 - 7.5% CO

Tubing, Condensate............................. .. 191746 20.. .. Tubing, Pressure.................................. .. 191562 21 .. .. U-Bolt Assembly.................................. .. 191938 22.. .. Valve Drain........................................... ... 26273 23 .. .. Vent Assembly..................................... .. 210494 24 .. .. Vent Flange.......................................... .191685-5 25 .. .. Washer, Plain....................................... .76820-18 26 .. ..

A drain line from the relief valve should terminate near a suitable drain. Do not thread, plug, or cap the end of the drain line. The pressure setting of the relief valve should not exceed the pressure capacity of any component in the system including the boiler. HIGH TEMPERATURE DEVICES Automatic Device The boiler control circuit contains a high temperature cutoff switch. This device shuts off the heating elements if excessive water temperatures are reached. The high temperature cutoff has an a

98883-3 I Relief Valve (LB Model)................................................ 210451-2 6........Strap, Cable (not shown).............................................. 99592-2 7........Tee, Condensate......................................................... 192040-1 8........Tee (For use w/relief valve): LW Model............................................................... 78685-4 LB Model.................................................................191584 9........Tee 2"x2"x2

Requires 120V 60Hz, maximum inlet gas pressure of 14" W.C. and activation of heater by an external temperature control. OPTIONAL POWER VENT KIT - For sidewall venting. WORKING PRESSURE - ASME approved, hydrostatically tested and certified for 160 psi (1100 kPa). * Model HW-399: 81% efficiency, Model HW-610: 80% efficiency. COMMERCIAL BOILERS HW-300 THRU HW-610 Domestic Hot Water Supply Not approved for instantaneous applications. FOR UNITS BUILT FOR U.S.A. FOR UNITS BUILT FOR CANADA HW M

O. Smith July 2011R GW/GWO-300 THROUGH GW/GWO-750 PG 1 OF 4 AOSDG25200 Commercial Gas Boilers GW SERIES INDOOR MODELS GWO SERIES OUTDOOR MODELS PG 2 OF 4 MODEL NUMBER BTU INPUT PER HOUR DIMENSIONS IN INCHES EXHAUST VENT AIR INLET WATER CONN. GAS PIPE (SEE DRAWINGS ABOVE) WIDTH A B C GW SERIES INDOOR MODELS GW-300 300,000 5 5 1-1/2 3/4 29-1/2 14-13/16 9 12 GW-400 399,900 6 6 1-1/2 1 35-3/4 17-15/16 9 14-3/4 GW-500 500,000 6 6 2 1 42 21-1/16 9 14-3/4 GW-650 650,000 8 8 2 1-1/4 51-3/8 25-3/4 9 14-3