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 125 HX 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 down 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 make-up air. A wood stove or furnace may pull combustible air down through the 125 HX vent system, leaving the cold infiltrating air capable of freezing the cold water in the 125 HX heat exchanger. More make up air is the solution. Follow the instructions on venting and checking adequacy of make up air. A HVAC specialist should be used to design solutions for providing more make-up air if necessary.

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 125HX 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.

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.

CLEARANCES

The 125 HX 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 - combustible construction listed below

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 B-1 vent is approved for 1 inch clearance.

Note: Typically, the minimum clearence 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.

Air Vents

(10 ¾ X 10 ¾ in. each)

 

125HX

 

125HX

 

Air Vents

 

(5 ½ X 5 ½ in. each)

 

 

MOUNTING INSTALLATION

The 125HX is design certified for mounting on a wall. Secure the two L shaped hooks, which are provided with heater, to a wall surface. Place them 13 ¼” apart as shown in Fig. 2.

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. 2.

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

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AquaStar 125HX LP, 125HX NG specifications Combustion AIR Requirements, Clearances, Mounting Installation
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125HX LP, 125HX NG specifications

The AquaStar 125HX NG and 125HX LP are highly efficient gas tankless water heaters designed to meet the demands of modern households. With their compact size and advanced technology, these units provide an endless supply of hot water while maintaining energy efficiency. Both models cater to natural gas and propane applications, making them versatile options for various installations.

One of the standout features of the AquaStar 125HX series is its ability to deliver a powerful output of up to 199,000 BTUs, ensuring that multiple hot water outlets can operate simultaneously without a drop in temperature. Users can enjoy the convenience of hot showers, laundry, and dishwashing all at once, making it an ideal choice for busy families or households with high hot water needs.

These models incorporate a sophisticated modulating gas valve that adjusts the gas flow based on the demand for hot water. This technology not only optimizes energy consumption but also contributes to extended unit life by minimizing wear and tear on the components. The AquaStar 125HX units also come equipped with a patented electronic ignition system, which eliminates the need for a standing pilot light and reduces gas consumption.

Furthermore, the AquaStar 125HX NG and 125HX LP feature a durable heat exchanger constructed from high-grade copper, which enhances thermal efficiency and prevents corrosion. This ensures a longer lifespan and increased reliability for homeowners. Additionally, the units are compact and wall-mounted, allowing for flexible installation in various spaces, including tight utility closets or outside walls.

Safety is also a top priority, with built-in overheat protection and a freeze protection feature that ensures the unit remains operational even in colder climates. The AquaStar 125HX series operates quietly, allowing users to enjoy the benefits of hot water without the disruptive noise commonly associated with traditional water heaters.

In summary, the AquaStar 125HX NG and 125HX LP are leading choices in the tankless water heater market, combining efficiency, reliability, and innovation. Their impressive output, advanced technologies, and compact design make them suitable for modern living, ensuring homeowners have access to hot water whenever they need it. With these features, AquaStar continues to set a high standard in water heating solutions.
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