AquaStar 125B NGS Maintenance and Service, Pilot burner with air screen/ pilot orifice

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INFORMATION ABOUT WATER TEMPERATURE

The AquaStar 125B LPS and 125B NGS water heaters have a gas control that modulates burner output in response to water flow. Its purpose is to ensure that the hot water temperature will remain steady, although the water flow demand might vary (down to 1/2 gal/minute). The AquaStar 125 B”S” will produce a temperature rise of approximately 90°F at flow rates between 0.5 and 1.8 gallons per minute unless the water has been preheated. If the incoming water is already hot, the burners will modulate accordingly so the outlet temperature will not exceed 140°F.

Cold water will have to be mixed in at the faucet to produce comfortable temperatures. Mixing in cold water will produce higher flow rates and will reduce risk of scalding. Note: 105° is the maximum recommended temperature for a hot bath. Handwashing should not be done in water hotter than 112°

-and cooler for older adults, young children or persons with sensory loss. Remember that scalding can occur in 20 seconds with 135° water.

MAINTENANCE AND SERVICE

(see maintenance table on back of manual)

Approximately once a year, the AquaStar should be checked and cleaned. To remove the front cover, first remove the incandescent particle tray, then unscrew the central screw located at the bottom of the front cover. Pull main cover out toward you and lift up and out . TH E FOLLOWI NG OP E RATION S SHOU LD B E PE R FOR M E D BY A QUALIFIED SERVICE PERSON:

Vent System: Should be checked annually. Clean and repair as needed.

Water Valve (Part # 8707002393): The water valve on this heater should be serviced periodically. Lubricate component #27 on page 14 with a small amount of silicon, faucet or lithium grease every two years to keep its o rings fresh and pushrod sliding smoothly. Every 3-5 years replace components #27 and #29 on page 14. The frequency will depend on the mineral content of the water and conditions of use or whenever signs of corrosion appear at the gas and water valve joint. Periodically check that the water inlet filter (#34 on page 14) is clean as well.

Pilot Flame: The pilot flame should burn with a clean sharp blue flame and should resemble the diagram in Fig 8. If the flame is yellow, or if the pilot knob has to remain depressed for a long time in order to keep the pilot lighted, the pilot burner and or the pilot burner orifice may need to be cleaned (NG), the orifice may need to be replaced(LP), and or the air screen may need cleaning. The pilot flame should envelop approximately 10 mm (3/8") of the tip of the thermocouple. If it is too small, the pilot burner must be cleaned. To obtain a spark, the position of the Piezo igniter electrode should be approximately 3 mm (1/8") from the pilot burner tip.

3mm

Correct gap between pilot burner tip and piezo electrode tip

Piezo Electrode

Air screen filter

10mm

3/8”

 

 

 

 

Thermocouple

Piezo

Electrode

Fig. 8 - Characteristic Pilot Flame

To clean the pilot burner and/ or the pilot orifice : Turn off the gas at the unit. Remove the cover of the heater. To do so, remove incandescent particle tray and unscrew the central screw located at the bottom of the front cover. Pull main cover out toward you and lift up and out. Pull the air screen off, wash it and blow any lint off (See Fig 9). The pilot orifices should also be cleaned or replaced. Do not enlarge the orifice. Do not use any wire or sharp object to clean orifices. Natural gas orifices are large enough that you can usually clean them by blowing through them. LP orifices, on the other hand, are too small to clean and should be replaced. See #3 in Trouble Shooting Section. To access the pilot orifice, remove 2 screws holding pilot assembly in place. Then loosen compression fittings to expose pilot orifice.

AIR SCREEN

PILOT ORIFICE

Fig. 9 - Pilot burner with air screen/ pilot orifice

Main Burner Flames: The main burner flames should be blue, with a more intense blue cone in the center core. Yellow flames could be a sign of wrong size gas orifices or dirty burners, or a blockage on the heat exchangers fins.

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Contents Table of Contents For Your SafetyUnpacking the Aquastar Heater FeaturesRequired Natural Gas Pressure at inlet tap Model 125BS Front View Side ViewTOP a Front B Back Sides Floor C Vent Diameter General Rules to Follow For Safe Operation Proper Location for Installing Your HeaterClearances Combustion AIR RequirementsAquastar 125 B S is design certified for mounting on a wall Mounting InstallationFigure a VentingFigure C 720 606 Masonry Chimneys6 Adaptor Used on High Altitude Vent Adaptor for High Altitude InstallationsFor LP GAS GAS Line Sizing For Natural GASMaximum Capacity of Semi-Rigid ColumnGAS Line Sizing Maximum Inlet GAS Flow Pressure SettingWater Connections Above 4.500 ft consult your local gas supplierOperating Instructions For Your Safety Read Before Lighting the PilotWhat to do if YOU Smell GAS To Turn OFF GAS to AppliancePilot burner with air screen/ pilot orifice Maintenance and ServicePilot Light will not Light Pilot Lights but Flame Goes OUT When Button is ReleasedAir in the Gas Line Gas pressure too low Burners do not Ignite When HOT Water is Turned onWater is TOO HOT Water is not HOT EnoughUnbalanced pressure in waterlines HOT Water Temperature Fluctuates / Unit DeactivatedDiagram of AquaStar 125 BS Interior Components Diagram and Parts List Interior Components Diagram Parts List 125BS Flow chart of Aquastar 125 BS General Limited Warranty720 606 720 606 BBT North AMERICA, Waitsfield, VT all rights reserved Bosch Group