Bosch 125FX LP, 125FX NG User Manual

INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC
INSTANTANEOUS TYPE WATER HEATER FOR USE WITH NATURAL AND
LIQUEFIED PETROLEUM GAS

MODEL 125FX LP and 125FX NG

(Flow Modulated with Electronic Ignition and Power Venting – a Type III Category Appliance)

Suitable for heating potable water only

Not approved for space heating purposes

Intended for variable flow applications with steady cold water inlet temperatures

WARNING

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.

WHA T TO DO IF YOU SMELL GAS

- Close gas valve. Open windows.

- 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.

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

6 720 606 519 (02.01) AL

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.

FEA TURING: Automatic V ariable Power Modulating Gas
V alve, Electronic Ignition and Power Venting

T ABLE OF CONTENTS

Specifications .................................................... Page 2

Rules for safe operation .................................... Page 4

Locating the Heater ............................................ Page 4

Combustion Air Requirements ............................ Page 5

Mounting the Heater........................................... Page 5

Venting the Heater ............................................. Page 6

Gas Connections ............................................... Page 9

Water Connections .......................................... Page 10

Electrical Connections ......................................Page 1 1

Safety before turning on the heater................... Page 12

Lighting and Operating instructions .................. Page 12

Setting water temperature ................................ Page 12

Maintenance & Service..................................... Page 13

Trouble Shooting .............................................. Page 14

Diagram of AquaS tar......................................... Page 17

Components and Parts List.............................. Page 18

Principle of Operation:

When a hot water faucet is opened, the flow of water through
the heater causes the gas valve to open. At the same time
a microswitch is activated which sends a spark to the pilot.
The flame sensor confirms that the pilot has been lighted
and allows the first two burners to ignite. The flame sensor
confirms correct activation and all burners ignite. The pilot
goes out. The power exhaust system runs as long as the
burners are on. 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, followed
immediately by the exhaust system. Y our hot water faucet
is an ignition key to turn on the water heater, giving you
control over your hot water energy use. Every time you turn
off your hot water faucet, the energy consumption for hot
water returns to zero.

AquaStar 125FX LP and 125FX NG Specifications

AQ125FXNG AQ125FXLPG

130 000 Btu/hr 125 000 Btu/hr

Gas input

max.

min.

28 000 Btu/hr 28 000 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"
Vent 4” (Category III Gas Appliance)
Gas Connection 1/2” NPT thread
Min. Water Pressure 18 Psi
Max. Water Pressure 150 Psi

FEATURES

- Electronic Pilot Ignition

- On/Off switch to activate system

- Power Venting with safety shutoff

- 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 .

- Safety flame sensor at pilot burner.

- Automatic overheating protection shut-off sensor.

- Stainless steel burners with stabilized blue flame.

- Built-in corrosion resistant power venter.

- Compact space saver: mounts on a wall with two hooks.

- Easily removable one-piece cover.

- Easy one person installation.

- Adjustable water flow restrictor to ensure that water flow
demand will not exceed the heating capacity of the heater .

BOSCH is constantly improving our products, therefore
specifications are subject to change without prior
notice.

UNP ACKING THE AQUASTAR HEATER

Shipping Weight 50.6 LB
Net Weight 44 LB

2.0 GPM at 90° rise

4.0 GPM at 45° rise
Min. Water Flow 1/2 gal/min
120V/60Hz 1.2 Amps
LP GAS Supply Pressure min. 11” W .C.

(before Aquastar regulator) 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: 9.9” 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: 5.7”W.C.

Natural Gas Burner Manifold pressure while
Aquastar is operating at maximum input: 5.38” W.C.

* Inlet gas pressure before Aquastar regulator must not
exceed this value. Pressure may need to be adjusted for
high altitudes, see page 10.

This heater is packed securely . The box includes two water connection fittings, a control knob, 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. The FXHOOD horizontal vent terminator is supplied separately from
the 125FX water heaters. There is a set of installation instructions in the FXHOOD box.

2

D084_089

FRONT VIEW SIDE VIEW

MINIMUM INST ALLATION CLEARANCES FROM COMBUSTIBLE AND NON
COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS

MODEL 125FX

TOP (A) 12 "
FRONT (B) 4 "
BACK 0 " *
SIDES 4 "
FLOOR (C) 12 " **
VENT DIAMETER 4 "

* On a combustible wall surface the unit should be mounted away
from the wall to provide adequate clearance of the vent pipe.
See page 5 for instructions.
** Some local codes require 18” in garage installations

AQUASTAR MODEL 125FX

3

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/NFP A 54.
In Canada: The Installation should conform with CGA
B149.(1,2) INST ALLATION 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 install your heater so that the venting complies

with all requirements. Venting must comply with all
requirements for Category III gas appliances. See section
on Venting the Heater , pages 6 and 7.

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
during any pressure testing of the gas supply piping system
at test pressures in excess of 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 that might burn. Do not install heater over carpeting.

7. Correct gas pressure is critical for the optimum

operation of this heater (see specifications on page 2 and
chart on page 9). Gas piping must be sized to provide the
required pressure at the maximum output of the heater.
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 under

water. Immediately call a qualified service technician to
inspect the appliance and to replace any part of the control
system and any gas control that has been under water.

10.When installed, the appliance must be electrically

grounded in accordance with local codes or, in the absence
of local codes, in accordance with the National Electrical
Code ANSINFP A 70 and/or the CSA 22.1 Electrical Code.

The heater may still operate even when improperly vented.
It will, however, be less ef ficient and could eventually damage
the heater. It could even result in human sickness or death
due to oxygen deprivation and carbon monoxide poisoning.
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).

Follow the guidelines below:

1. National building codes require that you do not install

this appliance in bathrooms, bedrooms, unvented
closet or any occupied rooms normally kept closed.

2. 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 by-products to
spill back into your home rather than venting to the outside
through the flue. Confirm that your Aquastar is venting
properly when all these other appliances are running. See
page 6 to test venting performance.

Do not obstruct the flow of combustion air to the
appliance. This appliance is power vented and uses room

air. Note: Electrical power is required to operate the power
exhaust. Proper air supply to the appliance is essential.
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.

3. Y our hot water lines should be kept short to save energy .
It is always best to have hot water lines insulated.

WARNING: DO NOT INSTALL IN AN AREA

WHERE IT COULD FREEZE. This heater is neither
designed for nor approved for outside installation.

Drain the heater entirely if freezing temperatures are
anticipated in area where heater is installed by
disconnecting both the inlet and outlet elbow connections
at the rear of heater. Additionally, remove the drain plug
under the water valve. See Fig 0.”

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.

4

Fig. 0 - Water heater drain plug

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

CLEARANCES

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 vent length
requirements 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 can rob the
make-up air in the AquaStar’s vent pipe, leaving the cold
infiltrating air capable of freezing the cold water in the
AquaStar heat exchanger. To prevent this the FXHOOD
horizontal vent terminator, which is supplied sep arately with
the water heater, needs to be installed on the end of the
horizontal vent run (see page 7). The FXHOOD is a CSA
approved vent terminator for the Aquastar 125FX and has a
built in back draft flapper .

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 6500 cubic feet for the AquaS tar 125FX 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, assume it is 20 % to 25%
of the total opening for wood louvers and 60 % to 75% for
metal louvers. Refer to the National Fuel Gas Code for
complete information. In buildings of tight construction all
air should be taken from outside.

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.

The Aquast ar 125FX 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 (305 mm)
B. Front 4 inches (102 mm)
C. Back 0 inches*
D. Sides 4 inch (102mm)
E. Bottom 12 inches (305 mm)**

* On a combustible wall surface the unit should be mounted
away from the wall to provide adequate clearance of the
vent pipe. See mounting instructions below.
** Some local codes require 18” in garage installations.

Clearance from vent pipe is dependent upon the clearance
rating of the venting material used. Single wall flue pipe
should be used and it is approved for 3” clearance for this
appliance. NOTE: See mounting instructions below to prop-
erly maintain a 3” clearance from the vent pipe to a com­bustible surface.

Note: this clearance can be reduced if combustible material
are protected as per table VI of the National Fuel Gas Code.

MOUNTING INST ALLATION

The Aquastar 125FX 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.
NOTE: Additionally the 125FX should be spaced away from
any combustible wall surface by a minimum of 1 ½” to
provide the needed 3” clearance between the vent pipe and
the wall surface. Review the FXHOOD horizontal vent
terminator instruction sheet (provided with the FXHOOD)
prior to heater installation.
In earthquake-prone zones, CEC recommends that
installers use a large washer and lag screw through the
existing holes used to hang the heater to affix the upper
third of the heater to the mounting board. T o affix the lower
third of the heater, CEC recommends that two new holes
be drilled in the heater’s frame, each one 16 inches below
the top two holes, and that washers and lag screws be
used to secure the lower portion of the heater to a spacing
board.
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.

5

WALL STUDS

13 ¼”

SUPPORT BOARD

1” X 4”

SPACE BOARD

Fig. 2 - Mounting the Heater

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 3.

SCREWS

INCANDESCENT PARTICLE TRAY

Fig. 3 - Incandescent Particle Tray Illustration

Minimum vent size diameter must be 4”. The appliance

must be located as close as practicable to a vent terminal.

Maximum vent length is 15 feet (4.6m) with two 90­degree elbows. This unit may be directly connected to

an approved vent termination with a 90-degree elbow. The
vent pipe connections must be secured to each other with
a minimum of 4 sheet metal screws per connection, and
all seams must be sealed with an approved high temperature
silicone sealant and aluminum duct tape. The vent system
must be gas tight. See Fig 4 for suggested venting
installation diagrams.

For best results, the horizontal vent system should be as
short and straight as possible. Vent pipe must be single
wall stainless steel (AL29-4C) or galvanized vent pipe of 26
minimum gauge. The maximum allowable horizontal

length of vent pipe is 15 feet. 2 elbows are allowable
within this maximum vent length. For each additional
elbow deduct 5 feet from maximum vent length. Any
vertical portion of the vent pipe that is part of the
horizontal vent system must be considered part of the
allowable 15 foot maximum. When the horizontal vent

run exceeds 5 feet the following criteria must be observed:

- Support the vent run at 4-foot intervals with overhead
hangers.

- Horizontal sections of vent connectors must rise ¼”
for every foot of horizontal length. Any vent section
greater than 45 degrees from vertical is considered
horizontal.

VENTING

WARNING: Do not reduce the vent pipe size.

This appliance must be vented horizontally to the outside
with sealed 4” single wall vent pipe following all local
ordinances and specifications for installing a power vented
Category III appliance. The 4” single wall vent pipe can be
either stainless steel (AL29-4C) or galvanized vent of at
least 26 gauge. Stainless steel is preferred. All connections
must be properly sealed. The vent system must be installed
by a qualified installer in accordance with all applicable
local gas codes. The venting system must be designed
and constructed so as to develop a positive flow adequate
to remove flue gases to the outdoors.

CAUTION: Aquast ar power vent system must be installed
by a qualified agency in accordance with these instructions.
If improperly installed a hazardous condition such as an
explosion or Carbon Monoxide poisoning could result.
Controlled Energy Corporation will not be responsible for
improperly installed appliances.

Plan the vent system so that code and manufacturer’s
clearances are maintained.
The minimum clearance from the top of the heater is 12
inches. Single wall vent pipe when mounted to the 125FX
requires a 3-inch clearance from combustibles. In all cases,
follow local codes:

- In Canada, CAN/CGA-B149 Installation Code for detailed
requirements.

- In USA, ANSI Z223.1 – latest edition, National Fuel Gas
Code for detailed.

Note: Single wall vent pipe cannot be used in any
concealed locations and should not be used in any unheated
space without an insulated chase. Unsealed 5” or 6” size
double wall B-Vent may be used as a chase for straight
lengths (no elbows) of the 4” single wall vent pipe. All
connections of the 4” single wall vent inside the 5” or 6”
B-Vent must be properly sealed. A 1” clearance is required
from the B-Vent pipe to combustibles.

Freeze Warning:

As mentioned on Page 5, negative air pressure in cold
climates will cause a reverse airflow in the vent system
that can freeze and damage the Aquast ar heat exchanger
when not in use. To prevent this the FXHOOD horizontal
vent terminator, which was supplied separately with the
water heater, needs to be installed on the end of the
horizontal vent run (see page 7). The FXHOOD is a CSA
approved vent terminator for the Aquastar 125FX and has a
built in back draft flapper .

Spill Switch Safety:

The 125FX is equipped with a Spill Switch; it’ s mounted on
the left side of the draft diverter (Flue gas safety device - #9
on page 19). Before leaving the installation site verify proper
Spill Switch operation by temporarily blocking termination
outlet. Once blocked then operate the heater, the unit
should shut down within 1-3 minutes when the flue gases
are blocked. You must reset the electrical power to the
heater after this safety test has been conducted, otherwise
the unit will not operate.

6

4”single wall venting only. Use
stainless steel (AL29-4C) or
galvanized pipe of 26 minimum
gauge must be used. Each
connection must be properly
sealed.

HORIZONT AL SIDE W ALL
* Maximum 15 feet with 2 elbows.
Deduct 5 feet for each additional elbow.

Approved Vent Terminal
(FXHOOD or other approved terminal)

The FXHOOD is design approved with the
Aquastar 125FX and has a built in back draft
flapper to prevent negative air from freezing the
Aquastar – see Fig. 5 for restrictions in loca­tion of vent terminal.

Approved Vent Terminal
(FXHOOD or other approved terminal)

The FXHOOD is design approved with the
Aquastar 125FX and has a built in back draft
flapper to prevent negative air from freezing the
Aquastar – see Fig. 5 for restrictions in loca­tion of vent terminal.

4”single wall venting only. Use
stainless steel (AL29-4C) or
galvanized pipe of 26 minimum
gauge must be used. Each
connection must be properly
sealed.

G181_274

Fig 4: Some Venting Guide Suggestions

An approved side wall vent terminal must be used when the water heater is vented through a side
wall. Locate in accordance with ANSI Z223.1 and local applicable codes. See Fig 5 for restrictions
in location of vent terminal in relation to opening doors and windows, grade, and forced air inlets.
Be certain that snow and ice will not interfere with the vent.

7

The approved vent terminal must be installed so that flue gases will not jeopardize people, overheat combustible structures
or enter into buildings, and so that proper clearances are maintained (See Fig 5).

a) The vent terminal shall not be less than 7 feet above a public walkway .
b) The vent terminal shall terminate at least 3 feet above any (mechanical) air inlet within 10 feet.
c) The vent terminal shall not be within a 6-foot radius from a gas meter or regulator.
d) The vent terminal shall be a minimum of 6 feet from any combustion air inlet.
e) The vent terminal shall terminate from an opening window, at least 4 feet below or 4 feet horizont ally from the

opening.
f ) The vent terminal shall terminate from a door, at least 1 foot above and 4 feet horizontally from the door .
g) The vent terminal shall not be less than 3 feet from an adjacent building.
h) The vent terminal shall not be less than 1 foot above grade.

1’ MIN

4’ MIN

VENT HOOD

SOFFIT

7’ MINIMUM ABOVE

PUBLIC WALKWAY

VENT HOOD MUST
BE MOUNTED ONE FOOT MINIMUM
ABOVE DOORS AND WINDOWS

4’ MIN

3’ ABOVE ANY FORCED

AIR INLET WITHIN 10’

ONE FOOT

ABOVE GRADE

1’ MIN

4’ MIN

4’ MIN

VENT HOOD MUST
BE MOUNTED FOUR FEET MINIMUM
BELOW WINDOWS

VENT HOOD MUST BE
MOUNTED FOUR FEET AWAY
FROM DOORS AND WINDOWS

Fig 5: Side wall exit locations for mechanical draft vent terminals

8

GAS PIPING, CONNECTIONS and Gas Regulator

Before connecting the gas supply , check the rating plate on the right side of the front cover to be sure that the heater is
rated for the same gas to which it will be connected.
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/NFP A 54.
In Canada: The Installation should conform with CGA B149 INST ALLA TION CODES and /or local installation codes.

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.

Follow boxed numbers for piping just one Aquast ar 125FX
(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.

(Based on a 0.60 Specific Gravity Gas) Btu numbers given
in thousands.

Nominal
Iron
Pipe Inter nal
Size, Diameter
inches inches 10 20 30 40 50 60 70 80 90 100 125 150 175 200

1/4 0.364 32 22 18 15 14 12 11 11 10 9 8 8 7 6
3/8 0.493 72 49 40 34 30 27 25 23 22 21 18 17 1 5 14
1/20.622132 92 7363 56504643403834 312826

3/4 0.824 278 190 152 130 115 105 96 90 84 79 72 64 59 55

1 1.049 520 350 285 245 215 195 180 170 160 150 130 120 110 100

1 1/4 1.380 1050 730 590 500 440 400 370 350 320 305 275 250 225 210
1 1/2 1.610 1600 1100 890 760 670 610 560 530 4 90 460 410 380 350 320

2 2.067 3050 2 10 0 1650 1450 1270 1150 105 0 990 930 870 780 710 650 610

2 1/2 2.469 4800 3300 2700 2300 2000 1850 1700 1600 1500 14 00 1250 1130 1050 980

3 3.068 8500 5 90 0 4700 4100 3600 3250 300 0 2800 2 60 0 2500 2200 2000 1850 1700
4 4.026 17,500 12,000 9,700 8,300 7,400 6,80 6,200 5,800 5,400 5,100 4,500 4,100 3,800 3500

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 W ater Column Inlet Pressure)
(Based on a Pressure Drop of 0.5 Inch Water
Column).

Maximum Capacity of Semi-Rigid
Tubing in Thousands of BTU per Hour of
Undiluted Liquified Petroleum Gases (at 1 1
inches Water Column Inlet Pressure)

(Based on a Pressure Drop of 0.5 Inch Water
Column)

* Source National Fuel Gas Code NFPA 54, ANSI Z223.1 - No
Additional Allowance is necessary for an ordinary number of fittings

Nominal
Iron Pipe
Size,
Inches 10 20 30 40 50 60 70 80 90 100 125 150

1/2 275 189 152 129 114 103 96 89 83 78 69 63
3/4 567 693 315 267 237 217 196 185 173 162 146 132

1 107 732 590 504 448 409 378 346 322 307 275 252
1 1/4 220 149 121 103 913 834 771 724 677 630 567 511
1 1/2 330 229 185 155 141 127 118 108 102 976 866 787
2 622 433 346 299 264 239 220 204 192 1811 1606 1496

Outside Length of Tubing, Fee t
Diameter,
Inch 10 20 30 40 50 60 70 80 90 100

3/8 39 26 21 19 _ _____
1/2 9262 50 41 37 3531292726
5/8 199 131 107 90 79 72 67 62 59 55
3/4 329 216 181 145 131 121 112 104 95 90
7/8 501 346 277 233 198 187 164 155 146 138

Black Iron Pipe
Length of Pipe, Feet

Copper

9

It is strongly recommended that the natural gas pipe line
be 3/4" for the entire distance. If the maximum length is
above 40 feet, use 1" line. Flexible tubing is NOT
recommended, but if it is to be used, oversize it. With LP
gas installation, the recommended sizes are 5/8" up to a
maximum of 20 feet distance, 3/4" up to 50 ft distance and
7/8" up to 100 feet.

National Fuel Gas Code requires that a sediment trap (drip
leg) be installed on gas appliances. The drip leg must be
accessible and not subject to freezing conditions. Install in
accordance with the recommendations of the gas supplier.

NOTE: The AquaStar 125FX is supplied with a gas
pressure regulator that must be installed on the heater
before attaching the gas supply line. See figure 6.
Failure to install the gas regulator as shown in figure
6 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 INLET PIPE

PRESSURE TAP

PLASTIC CAP

APPLIANCE PRESSURE
REGULAT OR
(with directional arrow on
reverse side pointing upward)

Fig. 6 - Appliance pressure regulator

(with directional arrow on reverse side pointing up)

The pressure regulator provided with the heater is adjusted
to deliver the proper gas pressure (as indicated on the
rating plate and in the manual for altitude up to 2000 feet
(660 meters) above sea level. On appliances being installed
above 2000 ft (660 meters) elevation, the inlet gas pressure
should be set at installation to the value shown below .

NOTE: The gas pressures specified below refer to
pressures taken at the pressure tap on the gas inlet
pipe just above the regulator (See Fig 6). These
readings should be taken while the heater is operating
at full input — i.e. maximum water flow with the
temperature dial selector turned all the way
clockwise.

WARNING: The heater must be disconnected from

the gas supply piping system during any pressure testing
of that system at test pressures in excess of .5 psig.
The water heater must be isolated from the gas supply
piping system by closing the manual shutoff valve during
any pressure testing of the gas supply piping system at
test pressures equal to or greater than .5 psig.
The water heater, including the pressure regulator provided
with it, must not be operated at gas supply pressures in
excess of .5 psig. If overpressure has occurred, such as
through improper testing of the gas lines or malfunction of
the supply system, the gas valve and regulator must be
checked for safe operation.
When your connections are made, check for gas leaks at
all joints (not just the ones you made). Apply some soapy
water to all gas fittings and gas valve. Soap bubbles are

a sign of a leak.
NOTE: Do not apply soap solution to pilot filter screen or

pilot orifice area. If you have a leak, shut off the gas. Af ter
verifying that required gaskets are in place, tighten
appropriate fittings to stop leak. Turn the gas on and check
again with a soapy solution. Never test for gas leaks using

a match or flame.

WATER CONNECTIONS

When facing the heater, the cold water inlet is on your right
and the hot water outlet is on your left.
Although water piping throughout your structure may be
other than copper, we recommend that copper piping be
used for at least three feet before and after the heater (follow
local codes if more stringent). Keep water inlet pipe to no
less than 1/2 inch diameter to allow the full flow capacity .
Remember that water pressure must be sufficient to activate
the heater when drawing hot water from the top floor. If the
hot and cold connections to the heater are reversed, the
heater will not function. The AquaStar 125FX is provided
with two flexible type connectors that must be connected
to the inlet and outlet fittings of the water valve as shown in
Figs 7 and 8. ½” Copper or brass fittings work best when
connected to the connectors. See Fig 8. These connectors
seal to the water valve by means of a union connection
with a washer type gasket at the joint. No pipe dope or
thread tape is to be used at these joints. Be certain there
are no loose particles or dirt in the piping. Blow out or flush
the lines before connecting to the AquaS tar . Full port valves
should be installed on both the cold water feed line and the
hot water outlet line to facilitate servicing the heater.
For installation on a private well system, be sure that the

water pressure is set between 30 and 50 psi.

INLET

WASHER

WA TER FIL TER

WA TER V ALVE

MAXIMUM INLET PRESSURE SETTINGS

Altitude Natural Gas Liquid Propane

inches W.C: inches W.C:

0' - 2.000 ft 5.38 9.9

2.000 ft - 4.500 ft 4.40 7.90

Above 4.500 ft consult your local gas provider .

10

FLEX
CONNECTORS

WASHER

OUTLET

Fig.7 - Water valve and water connectors, top view

- Typical setups are shown below with the pressure relief
valve attached. The pressure relief valve is supplied with
the heater, and should only be fitted on the hot water
outlet as shown. The cold water inlet setup will be
identical to diagrams below but without the pressure relief
valve.

- For ease of installation the piping setup should be
prepared as one whole piece with either threaded or
sweated connections. The entire assembly will then
mount easily against a wall and to the back of the
Aquastar .

THREADED ASSEMBL Y

1/2” FLEX

PIPE PRV TO
APPROPRIATE
DISCHARGE

SWEA TED ASSEMBLY

1/2” FLEX

PIPE PRV TO
APPROPRIATE
DISCHARGE

Fig. 8 - Plumbing connections for the Aquastar 125FX

ELECTRICAL CONNECTIONS

Connecting the pressure relief valve (PRV)

The listed pressure relief valve supplied with the heater must
be installed at the time of installation. Should a discharge
line be added to the PRV no valve is to be placed between
the PRV and the heater. No reducing coupling or other
restriction may be installed in the discharge line. The
discharge line must be installed such that it allows
complete drainage of both the PRV and the line. The location
of the PRV must be readily accessible for servicing or
replacement. and be mounted as close to the water heater
as possible. T o inst all the PRV , a suitable fitting connected
to an extension on a “T” fitting can be sweated to the hot
water line. See Fig 9.

Pressure

Pressure
Relief

Relief
Valve

Valve

HWSHWS

CWSCWS

Fig. 9 - Pressure Relief Valve

WARNING: This heater must be electrically grounded in accordance with the most recent edition of the National

Electrical Code, NFP A 70. In Canada, all electrical wiring to the heater should be in accordance with local codes and the
Canadian Electrical Code, CSA C22.1 Part 1. Do not rely on the gas or water piping to ground the metal parts of the
heater.
CAUTION: Label all wires prior to disconnection when servicing controls. Wiring error can cause improper and dangerous
operation. Verify proper operation af ter servicing.
The AquaS tar 125FX requires an electrical power supply from 120V AC 60Hz circuit and must be properly grounded.

- A means for switching off the 120 V AC power supply must be provided.

- The heater is wired as shown in the wiring diagram. (Fig 10).

E864_020

Fig 10: Wiring Diagram for AQ 125FX

1 - microswitch
2 - electric control box
3 - exhaust fan
4 - fuse
5 - circuit interrupter
6 - electronic control box
7 - temperature limiter
8 - sensors of exhaust gases

9 - ionization probe (flame

sensor)
10 - pilot electrode
11 - pilot electrovalve
12-

Diaphragm switch

13 - burner electrovalve
14 - power cord

11

OPERA TING INSTRUCTIONS

Before operating the heater, make sure that the system is
filled with water.

Open the cold water inlet supply to the heater fully .
Open a hot water faucet to permit the water to fill the heater
and the piping and to eliminate the air trapped in the system
Close the hot water faucet after the water flows freely and
all the air has escaped from the system. The water heater
is now ready to operate.

FOR YOUR SAFETY READ BEFORE
OPERATING YOUR HOT WATER HEATER

Warning: If you do not follow these instructions
exactly , a fire or explosion may result causing property
damage, personal injury or loss of life.

A. This appliance is equipped with electronic ignition for

lighting the pilot and main burners. When turning the heater
on, follow these instructions exactly .
B. Before operating the unit, set the On/Off switch to the
On (I) position. The On/Off switch is located behind the
flip-down coverplate on the front panel strip. Smell all around
the appliance area for gas. Be sure to smell next to the
floor because some gas is heavier than air and will settle
on the floor.

6. Turn the hot water faucet on to the minimum flow required
to activate the heater. The automatic ignition system
first ignites the safety pilot burner which then ignites the
main burner in about 4 seconds. The power exhaust will
then activate.

7. The pilot flame will extinguish 10-30 seconds after the
burners come on. The burners will remain on until the
hot water tap is turned off.

NOTE: On a first time installation, existence of air in the
gas supply line and in the water line may cause some
ignition delay . In that case, repeatedly open and close the
hot water tap in order to restart the ignition process until all
the air has been purged.

TO TURN OFF GAS TO APPLIANCE

Turn off the manual lever on the gas supply line to the heater
and set the ON/OFF switch to the OFF ( 0 ) position, see
Fig. 11.

To operate the heater, set the ON/OFF switch to position I.
The switch is located behind the flip down cover plate on
the front panel strip.
To shut down the gas to the heater , set the ON/OFF switch to
position 0

WHA T TO DO IF YOU SMELL GAS

- Do not try to light any appliance.

- Do not touch any electric 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.

C. Use only your hand to push in the on/off control button.
Never use tools. Follow these instructions exactly . If control
button is jammed, close the gas supply and call a qualified
service technician. Attempted forceful repair may result in
a fire or explosion.
D. Do not use this appliance if any part has been under
water. 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 under water.

LIGHTING AND OPERATING INSTRUCTIONS

1. STOP! Read the safety information on the front panel of

the heater.

2. The gas valve must be turned off by putting the On/Off
switch to position “O” (see fig. 12). Wait five (5) minutes
to clear out any gas. If you smell gas, STOP! Follow “B”
in the safety information above. If you don’t smell gas,
go to next step.

3. This water heater is equipped with a safety pilot burner
and an automatic ignition control system.

4. Set the ON/OFF switch (flip down cover plate on front
panel strip) marked I/O to the I position. In this position
the water heater is ready to use.

5. Verify that the power supply to the appliance is turned
on.

G667_091

Temperature Adjustment Knob

Decrease
temperature and
increase flow

G661_004

Increases temperature

and decreases flow

Fig. 11 - Principles of Operation

SETTING THE WATER TEMPERATURE

The AquaS tar 125FX LP and 125FX NG water heaters have
a gas control that modulates burner input in response to
flow. Its purpose is to ensure that the hot water temperature
will remain steady, although the demand for water flow
might vary (down to 1/2 gal/minute). To adjust the
temperature on your AquaS t ar , turn on a hot water faucet
to its maximum flow . At the AquaS t ar , turn the large knob
located beneath the main gas controls on the front of the
heater all the way to the right (clockwise). See Fig 12. This
will produce a temperature rise of approximately 90°F at
flow rates between .5 and 2.0 gallons per minute. Given
that average incoming water temperatures are 50°F, this
heater will produce approximately 140°F water at these
flow rates. Turning the dial all the way to the left
(counterclockwise) will produce a temperature rise of
approximately 45°F for flow rates between 1.0 and 4.0
gallons per minute. This will result in a higher flow rate, but
at cooler temperatures. Turning the dial to locations in

12

between will give various temperatures between 140° and
95°F at various flow rates between 2.0 and 4.0 gallons per
minute. The position you select on the temperature selector
dial will depend on the temperature of the incoming water
(50°F is average in the U.S.). In warm weather regions where
the incoming cold water is generally warmer, or during the
hot weather months in some other areas a midway setting
on the temperature selector knob will produce a
temperature rise of about 70°F, giving an output of
approximately 120°F. At this setting, if it is still necessary ,
one could mix a small amount of cold water in a shower
and have a comfortable shower at about 3 gallons/minute.
During the colder months, or in cold climate areas, it might
be necessary to set the control all the way clockwise to
the right for maximum temperature rise.
Do not supply the AquaStar 125FX with preheated water.
For this type of application, purchase a solar model 125 B
LPS or 125 B NGS.

Pilot Flame: The pilot flame should burn with a clean,
sharp, blue flame and should resemble the diagram in Fig.

13. If the flame is soft and yellow, the pilot burner orifice
may need to be cleaned or replaced. The pilot flame should
be approximately 2 inches long, extending past the flame
sensor. If the flame is too small, it will not reach the flame
sensor and the burners will not come on.

3mm

Correct gap between pilot
burner tip and electrode tip

Piezo Electrode

TEMPERATURE
ADJUSTMENT KNOB

Fig. 12 - T emperature Adjustment Knob

MAINTENANCE AND SERVICE
REVIEW MAINTENANCE TABLE ON

THE BACK OF THIS MANUAL

Approximately once a year, the AquaSt ar should be checked
and cleaned. To remove the front cover, first remove the
incandescent particle tray, then pull off the temperature
adjustment knob and unscrew and remove the plastic collar.
Unscrew the central screw located at the bottom of the
front cover. Pull main cover out toward you and lift up and
out. THE FOLLOWING OPERATIONS SHOULD BE
PERFORMED BY A QUALIFIED SERVICE PERSON:

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

Water Valve (Part # 87070024534): The water valve on
this heater should be serviced periodically. Lubricate
component #33 on page 19 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 #33 and #34 on page 19. 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 (#36 on page 19) is clean as well.

Flame sensor

Piezo

Electrode

Fig. 13 - Characteristic Pilot Flame

To clean the pilot burner and/or the pilot orifice: Turn

off the gas at the unit (Position ‘O’). Remove the cover of
the heater. To do so, pull off the temperature knob and
unscrew and remove the temperature knob collar. Pull main
cover out toward you and lift up and out. The pilot orifices
should also be cleaned or replaced. Do not enlarge the
orifice (see fig. 14). 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 the compression fitting and lift up pilot
burner to expose pilot orifice.

13

3. Water flow is not sufficient to activate heater.

Water flow rate at faucet is below minimum flow needed to
activate heater. When temperature adjustment knob is
turned all the way clockwise, the AquaStar model 125FX
requires 1/2 gallon per minute flow to activate the heater.
As a reference, this is a flow which would fill a quart jar in
30 seconds. If the temperature adjustment knob is turned
fully counterclockwise, a flow rate of 1.1 gallons/minute is
required to activate the heater.

4. Bad fuse

Check the viability of the fuse (see Fig 10 (#4) for location
of fuse). Replace if necessary.

PILOT ORIFICE

Fig. 14 - Pilot burner with pilot orifice

Main Burner Flames: The main burner flames should be

blue, with a more intense blue cone in the center core.
Y ellow flames could be a sign of wrong size gas orifices or
dirty burners, or a blockage on the heat exchangers fins.
If some burners have yellow flames while others have good
flames, it is likely that dust, lint or spider webs have partially
clogged the burner venturis. To clean the burners, contact
a gas service person.

Mineral Scale Build-up: AquaStars, when operated at
lower temperature settings, do not accumulate mineral
buildup. If however, the heater is used at the higher
temperature settings and the water has a high mineral
content, periodic descaling may be necessary . The heating
coils should be flushed with a descaling solution. Consult
your dealer or Controlled Energy for instructions.

TROUBLE SHOOTING (see maintenance table)

Introduction

The AquaStar 125FX pilot and burners are ignited by a
water flow valve. Numerous water related problems can
cause this water valve to malfunction such as: Insufficient
water flow volume to activate the burners at its minimum
flow requirement; Dirt in the water flow valve causing it to
malfunction; Sediment build-up in faucet aerators, or shower
heads; Uneven pressures between cold and hot with single
lever faucets; Plumbing cross overs. These water flow
related problems can cause the heater to deliver less than
its full output, or to fail to ignite or to shut down completely .

Problems are stated in upper case, bold face. Most common
causes for the problems follow in order of likelihood. The
suggested solutions require that the cover be taken off. To
do this, pull off the temperature knob and unscrew and
remove the temperature knob collar. Pull main cover out
toward you and lift up and out.

NO SPARK AT THE PILOT

1. On/Off switch is not ”On” (Position I).

The On/Off switch is located behind the flipdown cover plate
on the front panel strip. See fig. 1 1.

2. Bad electrical connections.

Be certain that all electrical connections are clean, tight,
and free of any moisture.

5. Water inlet filter is clogged

Water flow is restricted, preventing flow needed to activate
heater. Clean water inlet filter screen.

6. Cross over in water lines

T o confirm there is no cross-over in the plumbing, shut of f
the cold water supply to the AquaStar water heater and
open a hot water faucet. There should not be any water
flowing at that faucet. Water running is a sign of a plumbing
cross-over. Consult your plumber .

7. Microswitch needs to be adjusted or replaced.

If you do not hear a click when a tap is opened, the
microswitch needs to be adjusted. See Fig. 16 (#1) for
location and see Fig. 15 for adjustment. The microswitch
may need to be replaced.

Adjusting screw

G871_212

Fig. 15 - microswitch adjustment

Pilot does not spark with
water flow

Close water tap 1 Close water tap

1
2 Remove screw cap and

unscrew till sparking starts

3 Screw in turning one and a

half turns

Pilot always sparks
without water flow

2 Screw in adjusting screw

until it stops sparking

3 Continue to screw in

turning one and a half
turns more

8. Cold incoming water connection made to wrong
side of heater

Make sure cold water inlet connection is on the right side
when you are facing the AquaS tar .

9. Water valve parts may be dirty or components
damaged

First check that venturi is free of dirt particles. Water valve
and component parts must be totally free of dirt.

14

Mineral deposits can eventually (3-5 years in hard water
areas) corrode the water valve parts to a point where they
will need replacing. Any sign of moisture at the bleed

hole is a sign that the water valve needs to be
replaced immediately.

10. Loose connection at the ECO

Ignition sparker will not operate if the electrical circuit is
interrupted. Check that the connections to the ECO are
secure and tighten if necessary .

11. Reset electrical power to heater

If resetting the electrical power corrected the symptom then
likely the unit’s Safety S pill switch (Flue gas safety device

- #9 on page 19) had tripped from a flue blockage during
the previous usage. Inadequate combustion air to the room
area can also cause the unit to improperly vent. Improper
venting or insufficient combustion air must be corrected.
Consult a licensed professional to inspect the installation.

PILOT SPARKS CONTINUOUSLY WITH NO WATER
RUNNING

1. Microswitch needs adjustment

If no water is running, but pilot electrode continuously
sparks, the microswitch screw to the water valve needs
adjustment. See Figure 15.

PILOT LIGHTS BUT BURNERS WILL NOT COME ON

1. Confirm the flame sensor is in its proper position.
(see Fig. 13).

2. Sensors for exhaust gases may be loose.

The burners will not come on if the powered fan exhaust is
not working. Check that the unit is plugged in and that the
sensors for the flue gases are secure.

3. Confirm the ECO connections are secure.

SP ARKS APPEAR AT PILOT WHEN HOT WATER TAP
IS TURNED ON, BUT PILOT AND BURNERS WILL NOT
IGNITE

1. Air in the Gas Line
Note: Normally this is a problem only at the time of initial

installation, after the pipes have been worked on, or after a
propane tank has been allowed to empty , or after the heater
has been shut down for a long time.
Bleed all the air trapped in the gas line by turning the hot
water faucet on and off until the air has been cleared from
the line.

2. No gas to the AquaStar

A. Gas cock on gas line may not be open
B. Gas regulator may be shut or damaged. Replace or
unlock the regulator. Note: The regulator furnished with the
heater is exclusively designed for low gas pressure (less
than ½ psig). Excessive pressure will lock it up. Locking
usually happens when the gas pressure between the gas
tank and the water heater’s gas regulator has not been
properly regulated. See Page 2 for recommended correct
gas pressure. T o unlock a regulator , consult your gas supplier
or call CEC.

3. Pilot orifice clogged or gas valve is dirty

Clogging of the pilot burner can be caused by dust in the
air or dirt in the gas. The pilot orifice or gas filter may need
to be cleaned or replaced. See Fig. 14.

4. Water valve assembly needs to be checked

If the pilot orifice is clean, the water valve assembly should
be checked. The adjustment screw on the water valve micro­switch may not be tight enough (fig. 15). Remove central
cap beneath micro-switch assembly , carefully loosen the
adjustment screw until the pilot light ignites. At that point
retighten the screw one and a half turns. See Fig 15.

4. The Electronic Control Box (Fig 10) may need to be
replaced.

5. Burner electrovalve switch may need to be replaced
(see Fig. 10).

MAIN BURNERS GO OUT DURING HOT WA TER USE

1. Deficient exhaustion of flue gases

Check that vent is correct and clear of any obstructions,
that sensors for flue gases are secure and that electrical
connection has been made. If the heater will not come back
on, it will be necessary to turn the electrical supply to

the heater off and then on again.

2. Flow rate diminished below activation rate

Be certain that water flow is not less than required amount
to activate heater.

3. Unbalanced pressure in waterlines

The added restriction caused by the Aquastar in the hot
water system can result in uneven pressures between the
cold and the hot. In such cases when mixing cold water at
the tap, the lower hot water pressure may be overpowered
by a much higher cold water pressure, which may cause
the Aquastar burners to shut down (deactivate). Make sure
faucet aerators or shower heads are free of minerals.

Do not add any flow restrictor to the shower head.

T ypically this deactivation symptom is a result of the
hot water being too hot to use comfortably . Warm inlet
water generally causes this. Lowering the control
knob setting and/or reducing the inlet gas supply to
the heater should correct this deactivation symptom.

4. ECO (overheat sensor) tripped due to overheating

Do not feed preheated water to this water heater.

5. Pilot electrovalve switch may need to be replaced
(See Fig 10).

Call CEC.

6. Electronic Control Box may need to be replaced
(See Fig 10).

Call CEC.

5. Minimum inlet pressure on well pressure tank is
inadequate

Check the inlet water pressure. On a private well, raise the
minimum pressure setting to 30 psi. Confirm that the
pressure tank is not water logged.

15

WA TER IS TOO HOT

1. Temperature Selection too high

Turn the temperature adjustment knob counter-clockwise
(to the left) to lower the maximum water temperature.

Note: This will increase the activation flow rate.

2. Inlet water temperature is very warm (60º-75ºF)

Reduce inlet gas supply to lower the heaters degree rise.
Note: Only the Model 125BS should be used if the inlet
water is preheated.

3. Inlet filter screen is clogged, restricting flow

Remove screen and clean it.

WATER IS NOT HOT ENOUGH

1. Temperature selection is set too low.

Change the setting. Turn the temperature selector knob
clockwise (to the right). Note: this will decrease the

activation flow rate.

2. Water flow through the heater is higher than the
capacity of the AquaStar to heat it

Reduce the flow demand at the faucet. See flow rates at
specific temperatures on page 2.

3. Gas pressure is insufficient

It is extremely important for a tankless instantaneous
water heater to have the right size gas line to obtain
the correct gas pressure. See specifications on page 2.

Unlike storage tank water heaters, the burners of a tankless
water heater must be very powerful to heat water
instantaneously since they do this only at the time hot
water is actually being used. It is therefore imperative that
the gas pressure requirement be met exactly . Insuf ficient
gas pressure will directly affect the water temperature at
the time of usage. See page 2 for correct gas pressure
settings and see page 9 for proper gas line sizing.

HOT WATER TEMPERATURE FLUCTUATES /
UNIT DEACTIVATED

1. Unbalanced pressure in waterlines

The added restriction caused by the Aquastar in the hot
water system can result in uneven pressures between the
cold and the hot. In such cases when mixing cold water at
the tap, the lower hot water pressure may be overpowered
by a much higher cold water pressure, which may cause
the Aquastar burners to shut down (deactivate). Make sure
faucet aerators or shower heads are free of minerals.

Do not add any flow restrictor to the shower head.

T ypically this deactivation symptom is a result of the
hot water being too hot to use comfortably . Warm inlet
water generally causes this. Lowering the control
knob setting and/or reducing the inlet gas supply to
the heater should correct this deactivation symptom.

2. Cold water is mixing with the hot water between
the AquaStar and the outlet

See #4 under “NO SP ARK A T THE PILOT”.

3. Inlet water pressure is erratic due to inadequate
supply water pressure or saturated pressure tank on
well system

Check the inlet water pressure. On a private well, raise
minimum pressure setting to 30 psi. Confirm that the
pressure tank is not water logged.

4. Gas pressure is too low

See page 2 for correct specifications.

EXHAUST FAN DOES NOT OPERATE

1. Check the fuse (see fig 10)

2. Check all electrical connections

4. Gas supply is insufficient

Make sure your main gas line is fully opened. If using LP
gas, be sure that the size of the propane tank is adequate
to supply the required gas pressure. See gas pipe sizing
chart on page 9.

5. Cold water is mixing with the hot water between
the AquaStar and the outlet

Compare water temperature at outlet of the AquaStar (hold
the AquaSt ar’s outlet pipe with your hand) and at the t ap.
If these two are very different, check for mixing valve or
plumbing crossover (see “NO SPARK AT THE PILOT”
paragraph 4). Where automatic “anti-scald” valves are
required by code, lower the temperature setting on the
AquaSt ar as much as possible and balance the pressure
between cold and hot water after the AquaSt ar.

6. Gas valve above the water valve is not fully

opening.

If the internal water valve parts are damaged from water
quality or use, or there is evident corrosion where the water
valve and gas valve connect, then immediate service is
needed. See step 9 under the problem NO SP ARK A T THE
PILOT . White vinegar should be applied first to any corrosion
before the loosening of screws.

3. Check adjustment of fan microswitch

FAN CIRCULATES WHEN HOT WATER IS SHUT
OFF

1. Check adjustment of fan microswitch

16

Fig. 17 - Diagram of AquaS tar 125FX

14

1

3

2

4

5
6

13

9

7

10

8

11

12

1. Heat exchanger

2. Pilot assembly

3. Burner manifold gas
pressure test nipple

4. Main gas burner

5. Pilot gas tubing

6. Gas valve

7. Electronic control box

8. Power cord

9. on/off switch

10. Temperature adjustment selector

11. Microswitch

12. Gas inlet gas pressure test nipple

13. Electric box

14. Exhaust Fan

17

Fig. 18

INTERIOR COMPONENTS DIAGRAM

AND PARTS LIST 125FX

1 Front Cover 8 705 421 255
2 AquaS tar Decal 8 701 103 074
3 Plastic lower snap-on 8 705 506 451
4 T emperature adjustment knob complete 8 702 000 219
5 T emperature adjustment knob 8 702 000 1 1 1
6 Exhaust fan assembly 8 707 204 023
7 Draft diverter 8 705 505 451
8 Fan protection 8 701 302 164
9 Flue gas safety device 8 707 206 185

10 Heat Exchanger 8 705 406 235

1 1 Hot water pipe 8 700 705 556
12 Washer 8 710 103 045
13 Ov erheat senso r (EC O) 8 707 206 040
14 Cold water pipe 8 700 705 294
15 Main burner assembly 8 708 120 298 NG

8 708 120 296 LP
16 Washer for burner assembly 8 710 103 060
17 Throttle disc 8 700 100 189 LP only
18 Gas V alve 8 707 01 1 81 1 NG

8 707 01 1 812 LP
19 Diaphragm switch 8 708 504 021 NG

8 708 504 049 LP
20 Burner electrovalve 8 708 501 250
21 Pilot electrovalve 8 708 501 249
22 O-ring 8 700 205 120
23 Electrode ignition group 8 718 107 067
24 Pilot burner assembly 8 708 105 337 NG

8 708 105 491 LP
25 Injector pilot 8 708 200 069 NG

8 708 200 312 LP
26 Pilot gas tube 8 700 707 349
27 Washer 8 700 103 173
28 Electronic control box 8 707 207 011
29 Electric control box 8 707 101 021
30 On/Off switch 8 707 200 014
31 Microswitch 8 707 200 007
32 Water valve 8 707 002 534
33 Water valve repair kit 8 703 406 178
34 Slow ignition valve 8 708 503 063
35 D iap hra gm 8 700 503 053
3 6 Water inlet filter 8 700 507 059
37 Selector screw 8 708 500 251
38 V olumetric water governor 8 707 402 015
39 V enturi 8 708 205 249
4 0 Water connections gasket 8 710 103 043
41 Water elbow fitting 8 700 703 1 14

18

Fig. 18 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST

19

41-31segapeesELBATECNANETNIAM

RAEYYREVESRAEY2YREVESRAEY5-3YREVE

EVLAVRETAWETACIRBUL

EVLAVRETAWDLIUBER

NEERCSRETLIFRETAWTCEPSNI

YLBMESSATOLIPTCEPSNI

YLBMESSATNEVTCEPSNI

RENRUBNIAMTCEPSNI

†
†
†
†

†

†

Replacement Parts available from North American

Distributor

CONTROLLED ENERGY CORP.

340 Mad River Park

Waitsfield, Vermont 05673

Phone [phone]

Fax [phone]

www.controlledenergy.com

[e-mail]

Recycled paper

VULCANO T ermodomésticos S.A.

Estrada de Cacia

3801 - 856 Aveiro - PORTUGAL

© 2001 Controlled Energy Corporation, Waitsfield, VT
all rights reserved