Bosch 125B NGS User Manual
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INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC INSTANTANEOUS TYPE WATER HEATERS FOR USE WITH NATURAL AND LIQUEFIED PETROLEUM GAS
MODEL 125B LPS and 125B NGS (Thermostatically Modulated) Suitable for heating potable water only
Not approved for space heating purposes
Intended for domestic hot water with preheated inlet water as with solar hot water.
If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or death.
FOR YOUR SAFETY
Do not store or use gasoline or other flammable, combustible or corrosive vapors and liquids in the vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
- Do not try to light any appliance.
- Do not touch any electrical switch; do not use any phone in your building.
- Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
- If you cannot reach your gas supplier, call the fire department.
- Installation and service must be performed by a qualified installer, service agency or the gas supplier.
TABLE OF CONTENTS
WARNING: Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier. Upon completion of the installation, these instructions should be handed to the user of the appliance for future reference.
In the Commonwealth of Massachusetts this product must be installed by a licensed plumber or gas fitter.
FEATURING: Automatic Variable Power Modulating Gas Valve with Thermostatic Control
Warning: If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life.
Rules for safe operation ...............................................
Locating the Heater ......................................................
Combustion Air Requirements ....................................
Mounting the Heater .....................................................
Venting the Heater ........................................................
Gas Connections .......................................................
Water Connections ....................................................
Safety before lighting the pilot ................................
Lighting instructions ...................................................
Information on water temperature ...........................
Maintenance & Service .............................................
Trouble Shooting .........................................................
Diagram of AquaStar ..................................................
Components and Parts List ......................................
This well engineered, gas water heater has been specially designed to operate with incoming
It operates on the principle of heating water instantaneously “on demand”. When a hot water faucet is opened, cold water flows through the coils of the heat exchanger in the Aquastar. This same flow opens the gas valve, and the burners are ignited by the pilot flame. The heat exchanger coils absorb the heat generated by the burners and transfer heat to the water. When the hot water faucet is shut off, the gas valve automatically closes and the burners turn off. Your hot water faucet is an ignition key to turn on the water heater, giving you control over your hot water energy use. Each time you turn off your hot water faucet, you also shut off the water heater. On the Aquastar “S” model, if the incoming water is colder than the thermostat setting of the heater, the burners will ignite to heat the water in order to boost it and maintain it at the temperature setting. If the incoming water has been
-High Quality Materials for Long Working Life.
-Copper heating coils for endless supply of hot water.
-Burner output proportional to hot water flow demand for maximum energy efficiency.
-Automatic Thermostatic Control for steady hot water temperature
-Input BTU’s modulate to zero to prevent overheating of water from
-Safety thermocouple at pilot burner.
-Automatic overheating protection
-Stainless steel burners with stabilized blue flame.
-Compact space saver: mounts on a wall with two hooks.
-Easy one person installation.
-Adjustable water flow restrictor to ensure that water flow demand will not exceed the heating capacity of the heater.
-Easy pilot flame lighting with push button piezo ignition.
BOSCH is constantly improving our products, therefore specifications are subject to change without prior notice.
AquaStar 125B LPS and 125B NGS Specifications
Gas Input max.: 117,000 Btu/hr min.: 23,400 Btu/hr
Water Connection 1/2” Thread fitting NPT
H x W x D 29 3/4” x 18 1/4” x 8 3/4"
Gas Connection 1/2” NPT thread
Min. Water Pressure 18 Psi at 4 GPM
Max. Water Pressure 150 Psi
Shipping Weight 44 LB
Net Weight 42 LB
1.8 GPM at 90° rise
3.7 GPM at 45° rise
Min. Water Flow 1/2 gal/min
LP GAS Supply Pressure
(before Aquastar regulator) min.: 11” W.C. max.: 14” W.C.*
Required LP GAS Pressure at inlet
tap while Aquastar is operating: 10.5” W.C.
LP GAS Burner Manifold pressure while Aquastar is operating at maximum input: 9.0” W.C.
Natural Gas Supply Pressure
(before Aquastar regulator)
min.: 7” W.C.
max.: 14” W.C.*
Required Natural Gas Pressure at inlet tap
while Aquastar is operating:
Natural Gas Burner Manifold pressure while Aquastar is operating at maximum input: 4.2” W.C.
* Inlet gas pressure before Aquastar regulator must not exceed this value. Pressure may need to be adjusted for high altitudes, see page 11.
UNPACKING THE AQUASTAR HEATER
This heater is packed securely. The box includes two water connection fittings, a gas pressure regulator, a pressure relief valve, an incandescent particle tray, two hooks for hanging the heater, this manual, a warranty statement and a warranty registration card. Do not lose this manual, as there is a charge for replacement. Please complete and return the enclosed warranty registration card.
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MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND NON COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS
AQUASTAR MODEL 125BS
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GENERAL RULES TO FOLLOW
FOR SAFE OPERATION
1.You should follow these instructions when you install your heater. In the United States: The installation must conform with local codes or, in the absence of local codes, the National Fuel Gas Code ANSI Z223.1/NFPA 54.
In Canada: The Installation should conform with CGA B149.(1,2) INSTALLATION CODES and/or local installation codes.
2.Carefully plan where you install the heater. Correct combustion air supply and flue pipe installation are very important. If not installed correctly, fatal accidents can be caused by lack of air, carbon monoxide poisoning or fire.
3.The place where you install the heater must have enough ventilation. The National Fire Codes do not allow gas fired water heater installation in bathrooms, bedrooms or any occupied rooms normally kept closed. See the section below on locating the heater.
4.You must vent your heater. See section on VENTING, Page 6.
5.The appliance must be disconnected from the gas supply piping system during any pressure testing at pressures in excess of 1/2 Psig (3.5 kPa).
The appliance must be isolated from the gas supply piping system by closing its individual manual shutoff valve during any pressure testing of the gas supply piping system at test pressures equal to or more than 1/2 Psig (3.5Kpa). The appliance and its gas connection must be leak tested before placing the appliance in operation.
6.Keep water heater area clear and free from combustibles and flammable liquids. Do not locate the heater over any material which might burn.
7.Correct gas pressure is critical for the optimum operation of this heater (see specifications on page 2). Gas piping must be sized to provide the required pressure at the maximum output of the heater, while all the other gas appliances are in operation. Check with your local gas supplier, and see the section on connecting the gas supply.
8.Should overheating occur or the gas supply fail to shut off, turn off the gas supply at the manual gas shut off valve on the gas line.
9.Do not use this appliance if any part has been underwater. Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control which has been underwater.
This product is not approved for manufactured homes (mobile home), recreational vehicles (RV) or boats. Reference ANSI Z21.10.3.
This product is neither designed or approved for outside installations.
PROPER LOCATION FOR INSTALLING YOUR HEATER
Carefully select the location of your new heater. For your safety and for proper heater operation, you must provide an abundant supply of combustion air and a proper venting installation.
The heater may still operate even when improperly vented. It will, however, be less efficient and could eventually damage the heater. It could even result in human sickness or death due to oxygen deprivation and carbon monoxide poisoning. Follow the guidelines below:
1.Place your heater as close to a vent or chimney as possible.
2.National building codes require that you do not install this appliance in bathrooms, bedrooms, unvented closet or any occupied rooms normally kept closed.
3.Simultaneous operation of other appliances such as exhaust fans, ventilation systems, clothes dryers, fireplaces or wood stoves could create a vacuum effect in your home which could cause dangerous combustion
Do not obstruct the flow of combustion and ventilation air to the appliance. If installed near a clothes dryer it is very important that the dryer be properly vented. Failure to properly vent a dryer could result in a gradual accumulation of lint on the water heater fin coils and burners, leading to a dangerous condition of vent blockage and poor unsafe combustion.
4. Your hot water lines should be kept short to save energy. It is always best to have hot water lines insulated.
WARNING: The water in this water heater is cold and always remains cold except for the times that hot water is being used. DO NOT INSTALL IN AN AREA WHERE IT COULD FREEZE.
This heater is neither designed for not approved for outside installation. Drain the heater entirely if freezing temperatures are anticipated in the area where heater is installed by disconnecting both the inlet and outletelbow connections at the rear of heater. Additionally remove the drain plug under the water valve. See Fig 0.
Fig. 0 - Water heater drain plug
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WARNING: Flammable materials, gasoline, pressurized containers, or any other items or articles that are potentially fire hazards must NOT be placed on or adjacent to the heater. The appliance area must be kept free of all combustible materials, gasoline and other flammable vapors and liquids.
COMBUSTION AIR REQUIREMENTS
The AquaStar water heater holds cold water in its copper heat exchanger and brass water valve when not in use. Because of this, any cold air that comes in through the unit’s vent pipe is capable of freezing these components. This Installation Manual specifies the minimum vertical vent pipe and the amount of combustion air required for this unit. When all requirements are followed, the unit will operate properly and safely. However, there may still be a risk of freezing due to negative draft if all the combustion appliances in the area are not being supplied with a sufficient amount of
Observe the following instructions concerning combustion air.
Appliances located in unconfined spaces:
a)An unconfined space is one whose volume is greater than 50 cubic feet per 1000 Btu per hour of the combined rating of all appliances installed in the space. That would be 5850 cubic feet for the AquaStar 125B “S” alone.
b)In unconfined spaces in buildings of conventional frame, masonry, or metal construction, infiltration is normally adequate to provide air for combustion, ventilation, and dilution of flue gasses.
Appliances located in confined spaces:
The confined space must be provided with two permanent openings, one commencing within 12 inches of the top and one commencing within 12 inches of the bottom of the enclosure. Each opening must have a minimum free area of one square inch per:
-1000 Btu/hr if all air is taken from inside the building.
-2000 Btu/hr if all air is taken from the outside by horizontal ducts.
-4000 Btu/hr if all air is taken from the outside by direct openings or vertical ducts.
Or the confined space must be provided with one permanent opening or duct that is within 12 inches of the ceiling of the enclosure. This opening must have a minimum free area of one square inch per:
- 3000 Btu/hr if all air is taken from the outside by a direct opening or vertical duct.
(10 ¾ X 10 ¾ in. each)
(5 ½ X 5 ½ in. each)
Louvers, grills and screens have a blocking effect. If the effective free area is not known, increase the sizes of your openings by 75% if your louvers are wood and by 30% if your louvers are metal. Refer to the National Fuel Gas Code for complete information. In buildings of tight construction all air should be taken from outside.
The Aquastar 125 B “S” is design certified for installation on a combustible wall and for installation in an alcove or closet with the minimum clearances to combustible and non
A.Top 12 inches (306 mm)
B.Front 4 inches (102 mm)
C.Back 0 inches
D.Sides 4 inches (102mm)
E.Bottom 12 inches (306 mm)
Clearance from vent is dependent upon the clearance rating of the venting material used. For example, type
Note: Typically, the minimum clearance to combustible materials should not be less than 6” for single wall flue pipe. Note that this clearance can be reduced if combustible materials are protected as per table VI of the National Fuel Gas Code or if Type B gas vent is used.
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The Aquastar 125 B “S” is design certified for mounting on a wall.
Secure the two L shaped hooks provided with the heater to a wall surface. Place them 13 ¼ inches apart as shown in Fig 1. Do not install this appliance on a carpeted wall or over floor covering which is combustible, such as carpet. The heater must be mounted on a wall using appropriate anchoring materials. If wall is a stud wall sheathed with plasterboard, it is recommended that support board(s), either 1x4’s or 1/2" (minimum) plywood first be attached across a pair of studs and then the heater should be attached to the support boards. See Fig 1.
Expansion and contraction of piping due to changing water temperature in the pipes imparts movement to the heater which, if mounted directly to a brittle, friable board, such as plasterboard, can cause failure of mounting.
Before installing the unit, be certain you have the correct heater for your type of Gas – Propane or Natural Gas. Identification labels are found on the shipping box, and on the rating plate which is located on the right side panel of the cover. Also, each burner orifice is stamped with a number (79 for LPG and 120 for Natural Gas).
The incandescent particle tray (shipped loose in the carton with the water heater) must be attached at the bottom of the water heater front cover at the time of installation. Use the screws provided. See figure 2
INCANDESCENT PARTICLE TRAY
Fig. 2 - Incandescent Particle Tray Illustration
1” X 4”
Fig. 1 - Mounting the Heater
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Vent pipe connection. WARNING: Do not reduce the vent pipe size. See Fig. 3 for high altitude installations
The heater must be vented to the outside following all local ordinances and specifications for installing a gas appliance vent or chimney. The heater must be located as close as practicable to a vertically rising chimney or vent that has a listed vent cap at its termination point. The venting system must be designed and constructed so as to develop a positive flow adequate to remove flue gasses to the outdoors.
Consult the National Fuel Gas Code if the vent will have elbows or share venting with another natural draft appliance. The heater should never be common vented with a mechanically vented appliance. Single wall vent pipe is not recommended, if used consult the National Fuel Gas Code.
Horizontally venting to a sidewall vent terminator or a vertically constructed vent stack along an outside wall of a building is not permissible. A Powervent (Model
VERTICAL GAS VENT: A 5 inch diameter gas vent constructed of double wall Type B gas vent is recommended. 6 inch is required in elevations greater than 2000 feet, see Fig. 3. Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal. Horizontal sections must slope upwards at least ¼ inch for every foot of its horizontal length and be properly supported. Keep the horizontal section short and avoid too many elbows. The minimum vertical gas vent height allowed is 6 feet; horizontal vent connectors and elbows are not to be considered in the total gas vent height. All gas vent sections must be secured to each other with sheet metal screws and be properly supported.
The gas vent constructed of double wall Type B gas vent must terminate above the roof surface with a listed vent cap at a height that’s in accordance with Figure A or B and their table, provided they are at least 8 feet (2.4 m) from a vertical wall or similar obstruction. All other gas vents that are not able to terminate within the minimum specified height allowed must terminate not less than 2 feet (0.6 m) above the highest point where it’s passed through the roof and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet (3.1 m).
LOWEST DISCHARGE OPENING
LISTED VENT CAP
H (minimum) height from roof to lowest discharge opening
LISTED VENT CAP
LISTED GAS VENT
GAS VENT TERMINATIONS FOR LISTED VENT CAPS
H (minimum) feet
Flat to 6/12
6/12 to 7/12
Over 7/12 to 8/12
Over 8/12 to 9/12
Over 9/12 to 10/12
Over 10/12 to 11/12
Over 11/12 to 12/12
Over 12/12 to 14/12
Over 14/12 to 16/12
Over 16/12 to 18/12
Over 18/12 to 20/12
Over 20/12 to 21/12
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MASONRY CHIMNEY: Masonry chimneys shall be built and installed in accordance with NFPS 211 or local codes. A minimum 5” diameter gas vent pipe (metal double wall Type B), or an approved clay flue liner or a listed chimney lining system must be used when venting into a naturally drafting, internal masonry chimney. 6 inch is required in elevations greater than 2000 feet, see Fig. 3. Local codes may require the use of both gas ventand an approved lining system when venting into a masonry chimney. The Commonwealth of Massachusetts requires the use of a listed liner. Lining systems include approved clay flue lining, a listed chimney lining system or other approved material that will resist corrosion, erosion, softening, or cracking from exhaust flue gases at temperatures up to 1800 degrees F. The lining system must be listed for use with naturally drafting, draft hood equipped gas appliances. Follow local codes and refer to NFGC 54 and NFPA 58.
When connecting the water heater to a masonry chimney the following connector guidelines must be followed for safe and proper operation: An approved gas vent connector must be attached to the top of the water heater and rise vertically at least 12” before entering into an approved gas vent connector elbow. Any gas vent section that is greater than 45 degrees from the vertical is considered horizontal. If a horizontal vent connector is to be used to connect the vertical gas vent connector on the top of the water heater to the masonry chimney, that approved horizontal gas vent connector must be kept as short as possible and must be sloped upwards at least ¼” per foot of its length. This connector must be supported throughout its horizontal length. This horizontal gas vent connection may be no greater than 75% of the total vertical gas flue vent within the chimney. Also, an approved thimble or collar must be used when penetrating a masonry chimney.
A) Existing INTERIOR Masonry Chimney
The metal gas vent pipe should be permanently mounted inside the masonry chimney. Double wall Type B gas vent is recommended. The masonry chimney may have to be tile or metal lined before the insertion of the gas vent pipe; check local codes for clarification. The lining material must be listed for use only with naturally drafting, draft hood equipped gas appliances. Follow manufactures instructions for installation of listed lining material. You may not vent any other fuel burning appliances into any free space remaining in the chimney. The minimum vertical gas vent length within the masonry chimney should be no less than 5 ft (1.5 m); the vent terminator should extend at least 3 feet (0.9 m) above where the chimney meets the roofline and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet (3.1 m). The top of the gas vent should have an approved vent terminator. See Figure C.
B) Tile Lined INTERIOR Masonry Chimney
The masonry chimney must have an approved liner, ceramic tile, clay or metal. The masonry chimney must be able to accommodate the spent fuel gasses; consult a HVAC engineer for chimney capacity. A common venting
C) EXTERIOR masonry Chimney
Refer to the National Fuel Gas Code and consult a local HVAC professional.
LISTED VENT CAP
ESTABLISH A ONE
FOOT RISE BEFORE
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To check the draft:
Close all doors and windows to the outside.
Turn on all appliances that force air out of the building. These include all exhaust/ventilation fans, furnaces, clothes dryers, wood burning stoves, etc.
Open all doors between the AquaStar and these other appliances.
Run the unit for at least 10 minutes. Then hold an ordinary mirror at the side above the front shell. Any flue gases backdrafting will cause the mirror to fog. This is a serious health hazard and must be corrected. Poor venting can result in soot building up inside the heater, overheating of the heater and freezing of the heat exchanger in a freezing environment. The mirror will remain clear with a properly functioning draft.
Note: The burners of an instantaneous “on demand” water heater such as the AquaStar are only on at the time that hot water is actually being used, the vent pipe is therefore cold except for the short durations when hot water is being used, it is therefore very important that the venting and air supply be adequate to provide a good positive draft as soon as the burners turn on. See venting guide on back page.
The AquaStar 125B”S” instantaneous water heaters have
In U.S.A., ANSI Z223.1 - NFPA 54, National Fuel Gas Code for detailed requirements.
The vent connection for the Aquastar 125BS is 5 inches. However, for installations at high altitude (over 2000 feet above sea level) a six inch vent is required. A 5” by 6” vent adaptor must be affixed to the flue collar of the Aquastar with at least two screws. See Fig. 3.
5” X 6” ADAPTOR
USED ON HIGH ALTITUDE
Fig. 3 – Vent Adaptor for High Altitude Installations
WARNING: Failure TO INCREASE THE VENT SIZE TO SIX INCHES AND/or assure that the manifold pressure is set to proper value listed for applications at high altitudes will cause unsafe venting, asphyxiation, and will void CSA Certification.
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GAS CONNECTIONS and Gas Regulator
NOTE: The Aquastar 125 B”S” is supplied with a gas pressure regulator that must be installed on the heater before attaching the gas supply line. See figure 5. Failure to install the gas regulator as shown in figure 5 will be a violation of CSA certification of the unit. The regulator supplied with the heater is preset for the gas shown on the rating plate to the correct pressure. It is an appliance level regulator designed for (low inlet) pressure (less than 1/2 Psig or 15” W.C.) DO NOT connect to an unregulated or high pressure propane line or to a high pressure commercial
natural gas line.
GAS LINE SIZING
FOR NATURAL GAS
Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 0.3 in Water Column.
(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.
Follow boxed numbers for piping just one Aquastar 125BS (example: 3/4” B.I. Natural Gas pipe for 30 ft. will handle 152,000 btu’s). For multiple appliances combine the total btu input load and then refer to applicable chart below.
Length of Black Iron Pipe, Feet
FOR LP GAS
Maximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column Inlet Pressure) (Based on a Pressure Drop of 0.5 Inch Water Column).
Maximum Capacity of
Tubing in Thousands of BTU per Hour of Undiluted Liquified Petroleum Gases (at 11 inches Water Column Inlet Pressure)
(Based on a Pressure Drop of 0.5 Inch Water Column)
Black Iron Pipe
Length of Pipe, Feet
Length of Tubing, Feet
* Source National Fuel Gas Code NFPA 54, ANSI Z223.1 - No Additional Allowance is necessary for an ordinary number of fittings
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