GSW 520H User manual

320577-000
REV. 00 (10-12)
520H Direct Vent Indoor Models
On-Demand Condensing Water Heater
Installation Manual and Owner’s Guide
Gas Tankless Water Heater
520H Direct Vent Indoor Models
Suitable for potable water heating and space-heating*
* Please refer to local codes for space-heating compliance.
FEATURING
• ENDLESS HOT WATER
• ON-DEMAND USAGE
• COMPACT, SPACE SAVING
• ENERGY CONSERVATION
• COMPUTERIZED SAFETY
• NO PILOT LIGHT
• EASY-LINK SYSTEM
WARNING
This product must be installed
and serviced by a licensed
plumber, a licensed gas fitter,
or a professional service tech-
nician. Improper installation
and/or operation, or installation
by an unqualified person, will
void the warranty
- Do not store or use gasoline or other flam-
mable 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 electric switch, do not
use any phone in your building.
• Immediately call your gas supplier from a
neighbor's phone. Follow the gas suppli-
er'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.
If the information in these
instructions is not followed
exactly, a fire or explosion may
result causing property dam-
age, personal injury or death.
WARNING
520H model
only
If you have any questions,
please call or write to:
GSW Water Heating
599 Hill Street West
Fergus, ON Canada N1M 2X1
Toll Free: 1-888-479-8324

2
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
SAFETY GUIDELINES. . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Safety Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Included Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Optional Items. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Warning For Installations . . . . . . . . . . . . . . . . . . . . . . . 7
High-altitude Installations . . . . . . . . . . . . . . . . . . . . . . . 7
520H Model Installation . . . . . . . . . . . . . . . . . . . . . . . . 8
Venting Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
General
Exhaust vent (PVC vent)
Exhaust vent (Stainless steel vent)
Vent termination
PVC Venting Illustrations
Stainless steel Venting Illustrations
Vent clearances
Additional clearances
Gas Supply And Gas Pipe Sizing . . . . . . . . . . . . . . . . 14
Measuring inlet gas pressure
Water connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Pressure Relief Valve
Condensate Drain
Condensate Drain Connections
Case A: If a neutralizer is not required
Case B: If a neutralizer is required (installing the
Neutralizer assembly)
Electrical Connections. . . . . . . . . . . . . . . . . . . . . . . . . 17
Remote Controller Connection . . . . . . . . . . . . . . . . . . 18
Pump Control Connection. . . . . . . . . . . . . . . . . . . . . . 18
Pump Control Modes . . . . . . . . . . . . . . . . . . . . . . . . . 19
A) Recirculation Control: No. 5 ON
B) Storage Tank Circulation Control:
No.6 ON
C) Energy Conserving Recirculation:
No.5 and No.6 ON
D) Normal Control (Default setting):
No.5 and No.6 OFF
Easy-link System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
General
Easy-Link Connection Procedures
APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Space-Heating Applications . . . . . . . . . . . . . . . . . . . . 23
Recirculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Dual-purpose hot water heating . . . . . . . . . . . . . . . . . 24
INITIAL OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
OPERATING SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . .26
NORMAL OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . .28
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Temperature Settings . . . . . . . . . . . . . . . . . . . . . . . . . 28
On The 520H
Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Freeze Protection System. . . . . . . . . . . . . . . . . . . . . . 29
MAINTENANCE AND SERVICE . . . . . . . . . . . . . . . . . . .29
Unit Draining And Filter Cleaning . . . . . . . . . . . . . . . . 29
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . .30
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Error Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Single Unit Installations
Easy-Link System
Fault Analysis Of Error Codes . . . . . . . . . . . . . . . . . . 32
COMPONENTS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . .33
Case Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
520H
Computer Board Assembly. . . . . . . . . . . . . . . . . . . . . 33
520H
Burner Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
520H
Water Way Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 34
520H
PARTS LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
OUTPUT TEMPERATURE CHART . . . . . . . . . . . . . . . . .37
520H Models
LIMITED WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Table of Contents

3
SPECIFICATIONS
Model 520H
Natural Gas Input
(Operating Range) Min.: 13,000 BTU/h Max.: 199,000 BTU/h
Propane Input
(Operating Range) Min.: 13,000 BTUh Max.: 199,000 BTU/h
Gas Connection 3/4" NPT
Water Connections 3/4" NPT
Condensate Drain Port
Connection 1/2" NPT
Water Pressure 5 - 150 psi*
Natural Gas Inlet
Pressure Min. 5.0" WC Max. 10.5" WC
Propane Min. Inlet
Pressure 8.0" WC Max. 14.0" WC
Manifold Pressure of
the 520H Natural: 3.2" WC Propane: 5.5" WC
Weight 33.1Kg (73 lbs.)
Dimensions H 651mm (25.6 in.) x W 470mm (18.5 in.) x D 315mm
(12.4 in.)
Ignition Electric Ignition
Electric
Supply 120 VAC / 60 Hz
Consumption
Operating
(520H) 152 W (1.27A)
Standby 8.2 W (0.07A)
Freeze-
Protection 207 W (1.73A)
*40 psi or above is recommended for maximum flow
NOTE
* Check the rating plate to ensure this product matches
your specifications.
* The manufacturer reserves the right to discontinue,
or change at any time, specifications or designs
without notice and without incurring obligations.
INTRODUCTION
This manual provides information necessary for the
installation, operation, and maintenance of the 520H.
The model description is listed on the rating plate which
is attached to the side panel of the water heater.
Please read all installation instructions completely before
installing this product.
If you have any problems or questions regarding this
equipment, consult with the manufacturer or its local
representative.
The 520H is an on-demand, tankless water heaters
designed to efficiently supply endless hot water for your
needs.
The 520H is a high efficiency model with an in-build sec-
ondary heat exchanger that absorbs latent heat from the
exhaust gas.
The principle behind the 520H Water Heater is simple:
Intake port
Primary heat
exchanger
Burner
Cold Water
Inlet
Fan motor
Thermistor
PCB
Hot Water
Outlet
Exhaust
Secondary heat
exchanger
Thermistor
Bypass valve
Water control
valve
Flow sensor
Thermistor
Condensate
drain port
Gas Valve
Gas
Inlet
*This diagram illustrates tankless water heater design con-
cepts only and does not accurately represent to the 520H
physical description.
A hot water tap is turned on.
Water enters the heater.
The water flow sensor detects the water flow.
The computer automatically ignites the burner.
Water circulates through the heat exchanger and then
gets hot.
The computer will modulate the gas supply valve and
water flow to produce the right amount of hot water at the
correct temperature.
When the tap is turned off, the unit shuts down.
•
•
•
•
•
•
•
1.
2.
3.
4.
5.
6.
7.

4
SAFETY GUIDELINES
Safety Definitions
DANGER
Indicates an imminently hazardous situa-
tion which, if not avoided, will result in death
or serious injury.
WARNING
Indicates an imminently hazardous situa-
tion which, if not avoided, could result in
death or serious injury.
CAUTION
Indicates an imminently hazardous situa-
tion which, if not avoided, could result in
minor or moderate injury.
General
1. Follow all local codes, or in the absence of local codes,
the most recent edition of CSA B149.1 Natural Gas,
Propane Installation Code.
2. Properly ground the unit in accordance with all local
codes or in the absence of local codes, with CSA stan-
dard C22.1 Canadian Electrical Code Part 1.
3. Carefully plan where you intend
to install your 520H Water Heater.
Please ensure:
Your water heater will have
enough combustible air and
proper ventilation.
Locate your heater where water
leakage will not damage sur-
rounding areas (please refer to
pg. 5).
4. Check the rating plate for the cor-
rect GAS TYPE, GAS PRESSURE,
WATER PRESSURE and ELECTRIC RATING
*If this unit does not match your requirements, do not
install and consult with the manufacturer.
5. If any problem should occur, turn off all hot water taps
and turn off the gas. Then call a trained technician or the
Gas Company or the manufacturer.
•
•
WARNING
Water temperatures over 52°C (125°F)
can cause severe burns instantly or
death from scalding. The water tem-
perature is set at 49ºC (120ºF) from the
factory to minimize any scalding risk.
Before bathing or showering always
check the water temperature.
Do not store or use gasoline or other
flammables, vapors, or liquids in the
vicinity of this appliance.
Do not reverse the water and/or gas
connections as this will damage the gas
valves and can cause severe injury or
death. Follow the diagram on pg. 15
when installing your water heater:
Do not use this appliance if any part has
been in contact with or been immersed
in water. Immediately call a licensed
plumber, a licensed gas fitter, or a pro-
fessional service technician to inspect
and/or service the unit if necessary.
Do not disconnect the electrical supply if
the ambient temperature will drop below
freezing. The Freeze Prevention System
only works if the unit has electrical
power. The warranty will not be covered
if the heat exchanger is damaged due
to freezing. Refer to the section on the
Freeze Protection System on pg. 29 for
more information.
•
•
•
•
•
INSTALLATION
All gas water heaters require careful and correct installation
to ensure safe and efficient operation. This manual must be
followed exactly. Read the “Safety Guidelines" section at the
beginning of this manual.
WARNING
• Installation and service must be per-
formed by a qualified installer (for exam-
ple, a licensed plumber or gas fitter),
otherwise the warranty will be void.
• The installer (licensed professional) is
responsible for the correct installation of
your Water Heater and for compliance
with all national, state/provincial, and
local codes.
PLEASEREADTHISMANUALCAREFULLYAND FOLLOW
ALL DIRECTIONS.
Rating plateRating plate

5
CAUTION
• The warranty will not cover damage
caused by water quality.
• Only potable water or potable water
/ glycol mixtures can be used with
this water heater. Do not introduce
pool or spa water, or any chemically
treated water into the water heater.
• Water hardness levels must not
exceed 7 grains per gallon (120
ppm) for single family domestic
applications or more than 4 grains
per gallon (70 ppm) for all other
types of applications. Water hard-
ness leads to scale formation and
may affect/damage the water heater.
Hard water scaling must be avoided
or controlled by proper water treat-
ment.
• Water pH levels must be between
6.5 and 8.5
• Well water must be treated.
WARNING
• Although this water heater is designed to
operate with minimal sound, the manu-
facturer does not recommend installing
the unit on a wall adjacent to a bedroom,
or a room that is intended for quiet study
or meditation, etc.
• Locate your heater close to a drain
where water leakage will not do damage
to surrounding areas. As with any water
heating appliance, the potential for leak-
age at some time in the life of the prod-
uct does exist. The manufacturer will not
be responsible for any water damage
that may occur. If you install a drain pan
under the unit, ensure that it will not
restrict the combustion air flow.
• The 520H models are high efficien-
cy products that create condensation.
A condensation drain tube must be
installed with these models to discharge
condensate into a drain outlet. For more
information, refer to pg. 15.
• The manufacturer does not recommend
installing the 520H model in an attic due
to safety issues. If you install your 520H
model in an attic:
• Make sure your unit will have
enough combustion air and proper
ventilation.
• Keep the area around you’re the
water heater clean. When dust col-
lects on the flame sensor, the water
heater will shut down on errors.
• Locate unit for easy access for ser-
vice and maintenance.
• A drain pan, or other means of pro-
tection against water damage, is
required to be installed under the
water heater in case of leaks.
General
1. Follow all local codes, or in the absence of local codes,
the most recent edition of CSA B149.1 Natural Gas,
Propane Installation Code.
2. The manifold gas pressure is preset at the factory. It is
computer controlled and should not need adjustment.
3. Maintain proper space for servicing. Install the unit so
that it can be connected or removed easily. Refer to pg.
7, and pg. 8 for proper clearances.
4. The electrical connection requires a means of disconnec-
tion, to terminate power to the water heater for servicing
and safety purposes.
5. If you will be installing the unit in a contaminated area
with a high level of dust, sand, flour, aerosols or other
contaminants/chemicals, they can become airborne and
enter and build up within the fan and burner causing
damage to the unit.
6. Particles from flour, aerosols, and other contaminants
may clog the air vent or reduce the functions of the rotat-
ing fan and cause improper burning of the gas. Regularly
ensure that the area around the unit is dust- or debris-
free; regular maintenance is recommended for these
types of environment.
7. Do not install the unit where the exhaust vent is pointing
into any opening in a building or where the noise may
disturb your neighbors. Make sure the vent termination
meets the required distance by local code from any
doorway or opening to prevent exhaust from entering a
building (refer to pg. 12).
Included Accessories
Check that the installation manual, the communication
cable, the product registration card and the PVC adaptor
are included with the unit (the adaptor comes with the 520H
model only).
Items
Manual Qty: 1
Communication Cable (Gray) Qty: 1
Product Registration Card Qty: 1
TH-PA01 PVC adaptor
(520H model only) Qty: 1
For details on how to connect the adaptor, refer to pg.10 &.
11.

6
Optional Items
1. Temperature Remote Controller (TM-RE30):
The Temperature Remote Controller has two functions. It allows the output
temperature from the 520H to be adjusted within the range of 38°C to 85°C
(100°F to 185°F), and it also works as a diagnostic tool that will give a con-
cise error code whenever there is a problem with the unit. The temperature
options are 38°C (100°F), 40.5°C (105°F), 43°C (110°F), 46°C (115°F), 49°C
(120°F), 52°C (125°F), 55°C (130°F), 57°C (135°F), 60°C (140°F), 63°C
(145°F), 65.5°C (150°F), 68°C (155°F), 71°C (160°F), 74°C (165°F), 77°C
(170°F), 79.5°C (175°F), 82°C (180°F) and 85°C (185°F). See the trouble
shooting section for information on possible error codes.
2. Pipe cover (TH-PC02): The Pipe cover protects the plumbing pipes to the 520H models from unex-
pected adjustments. This pipe cover is fixed to the bottom of the water heat-
er, which hides the plumbing and improves the visual aspects of the whole
installation for the water heater.
3. Wall thimble with Termination (TK-KPWL4 and TK-KPWH4):
Louver Termination
TK-KPWL4 Hood Termination TK-KPWH4 These terminations are used when venting out through the wall and are
compatible with the T-Vent pipe system.
These terminations are special stainless steel vents for gas appliances and
are UL listed as Category II, III and IV. There are two types of terminations:
the Louver termination and the Hood termination. For different wall thick-
nesses, there are two ranges of lengths available (refer to the venting bro-
chure for details).
Install these vent terminations in accordance with their installation instruc-
tions and any applicable local codes.
4. Neutralizer kit (TH-NT01): The Neutralizer assembly neutralizes the condensate (acidic water) that
forms in the secondary heat exchanger of the 520H models. It connects to
the condensate drain port of the 520H models by using connectors included
with the neutralizer kit. Refer to pg. 16 for the details.

7
Warning For Installations
FOR YOUR SAFETY, READ
BEFORE INSTALLATION
Do not install the heater
where water, debris or flam-
mable vapors may get into
the flue terminal. This may
cause damage to the heater
and void the warranty.
Do not have the vent ter-
minal pointing toward any
opening into a building. Do
not locate your heater in a
pit or location where gas
and water can accumulate.
Do not install next to a dryer
or any source of airborne
debris that can be trapped
inside the combustion
chamber, unless the system
is direct vented. •
High-altitude Installations
Check the elevation where your water heater is installed.
Set DIPswitches shown in the table below depending on the
altitude. These DIPswitches (No. 5 and No. 6) are on the
computer board on the left bank only.
Altitude 0 to 2,500 ft
(default) 2,500 to 4,000 ft 4,000 to 5,000 ft Over 5,000 ft
Switch
No.5 OFF ON OFF
Consult our
Technical
Services
Department
at 1-888-
479-8324
Switch
No.6 OFF OFF ON
10
9
8
7
6
5
4
3
2
1
ON
10
9
8
7
6
5
4
3
2
1
ON
10
9
8
7
6
5
4
3
2
1
ON
The dark squares indicate the direction the DIPswitches
should be set to.
DO NOT
adjust any DIPswitches on the right bank.
Left bank of
DIP switches

8
520H Model Installation
The 520H models are equipped with a thermistor and hi-limit
switch for the exhaust gas, detecting excess temperatures
within the flue and enabling the unit to safely stop opera-
tions if needed. These components are always monitoring
exhaust gas conditions in order to prevent heat damage to
PVC (Plastic) venting if PVC is used.
If the exhaust gas temperature exceeds 60°C (140°F), these
components will enable the unit to safely stop operations.
520H model requires a 102mm (4 in.) make-up intake air
supply pipe. The intake pipe must be sealed airtight.
Air supply pipe can be made of ABS, PVC, galvanized
steel, corrugated stainless steel, or Category lll / IV stain-
less steel.
In any areas subject to freezing temperatures, the manu-
facturer highly recommends an indoor installation with
the 520H model. In such an installation, freezing issues
can only occur if cold air enters through the venting into
the heat exchanger, whether by negative pressures
within the installation location or by strong outside winds.
It is the installer’s responsibility to be aware of these
issues and take all preventative measures. The manu-
facturer will not be responsible for any damage to the
heat exchanger as a result of freezing. The warranty will
not be covered if the heat exchanger is damaged due to
freezing. Refer to the section on the Freeze Protection
System on pg. 29 for more information.
Sidewall venting is recommended for the 520H models.
Vertical venting (roof termination) is acceptable.
The manufacturer recommends running the exhaust
vent and the intake pipe as parallel as possible.
The PVC adaptor is used to make the connection
between the 520H vent collar and PVC vent pipe easier
and for maintenance purposes.
Maintain Clearances.
Bottom 305mm
(12 in.)
Side
76mm
(3 in.) Back
13mm
(0.5 in.)
Front 76mm
(4 in.) (610mm
(24 in.)
Recommended
for
Maintenance)
Top 305mm
(12 in.)
Side
76mm
(3 in.)
•
•
•
•
•
•
Venting Instructions
General
WARNING
Improper venting of this appliance can
result in excessive levels of carbon mon-
oxide which can result in severe personal
injury or death.
The 520H models must be vented in accordance with
the section “Venting of Equipment" of the latest edition of
Section 7 of the CSA B149.1 Natural Gas and Propane
Installation Code as well as applicable local building
codes. When installing the vent system, all appli-
cable national and local codes must be
followed. If you install thimbles, fire stops
or other protective devices and they pen-
etrate any combustible or noncombustible
construction, be sure to follow all appli-
cable national and local codes.
The use of venting materials approved for Category III/IV
appliances is recommended whenever possible. However,
520H may also be vented with plastic pipe materials such
as PVC. For details, please refer to the Exhaust vent (PVC
vent) section below. Vent installations which utilize plastic
vent systems must use venting that complies with ULC
S636.
Exhaust vent (PVC vent)
The 520H models can be connected with PVC venting certi-
fied to ULC S636 standards.
The maximum length of exhaust vent piping must not
exceed 15.24m (50 ft.) for 102mm (4 in.) venting and
7.6m (25 ft.) for 76mm (3 in.) venting (deducting 5 ft. for
each elbow used in the venting system). Do not use more
than 5 elbows for 102mm (4 in.) venting and 2 elbows for
76mm (3 in.) venting.
When the horizontal vent run exceeds 1.5m (5 ft.), sup-
port the vent run at 915mm (3 ft.) intervals with overhead
hangers.
•
•

9
Diameter Max. No. of
Elbow
Max. Vertical &
Horizontal (Total) Vent
Length
76mm
(3 in.) 2 7.6m (25 ft.)
102mm
(4 in.) 5 15.24m (50 ft.)
* For each elbow added, deduct 1.5m (5 ft.) from max.
vent length.
No. of
Elbows
Max. Vertical or Horizontal Length
76mm (3 in.)
venting 102mm (4 in.) venting
0 7.6m (25 ft.) 15.24m (50 ft.)
1 6m (20 ft.) 13.7m (45 ft.)
2 4.5m (15 ft.) 12.2m (40 ft.)
5 N/A 7.6m (25 ft.)
Excludes elbow termination, rain caps, or the 76mm
(3 in) PVC Concentric Termination
For details on the vent connection to the 520H, refer to pg.
10 & 11.
Exhaust vent (Stainless steel vent)
This is a Category IV appliance and must be vented accord-
ingly. The vent system must be sealed air tight. All seams
and joints without gaskets must be sealed with high heat
resistant silicone sealant or UL listed aluminum adhesive
tape having a minimum temperature rating of 72°C (160°F).
For best results, a vent system should be as short and
straight as possible.
The 520H is a Category IV appliance and must be vented
accordingly with any 102mm (4 in.) vent approved for use
with Category III/IV or Special BH type gas vent.
The manufacturer recommends the “T-Vent" line manu-
factured by TAKAGI (Refer to Takagi’s “T-Vent" brochure
for details). However, the following are also UL listed
manufacturers: ProTech Systems Inc. (FasNSeal), Flex-L
Inc., Z-Flex Inc. (Z-Vent III), Metal-Fab Inc., and Heat-
Fab Inc. (Saf- T Vent).
Follow the vent pipe manufacturer’s instructions when
installing the vent pipe.
Do not common vent this appliance with any other vented
appliance (Do not terminate vent into a chimney. If the
vent must go through the chimney, the vent must run
all the way through the chimney with Category III / IV
approved or Special BH vent pipe).
The maximum length of exhaust vent piping must not
exceed 15.24m (50 ft.) (deducting 1.5m (5 ft.) for each
elbow used in the venting system). Do not use more than
5 elbows.
When the horizontal vent run exceeds 1.5m (5 ft.), sup-
port the vent run at 915mm (3 ft.) intervals with overhead
hangars.
•
•
•
•
•
•
Diameter Max. No. of
Elbow
Max. Vertical &
Horizontal (Total) Vent
Length
102mm
(4 in.) 5 15.24m (50 ft.)
* For each elbow added, deduct 1.5m (5 ft.) from max.
Vent length.
No. of
Elbows Max. Vertical or Horizontal Length
0 15.24m (50 ft.)
1 13.7m (45 ft.)
2 12.2m (40 ft.)
5 7.6m (5 ft.)
Vent termination
WARNING
Improper installation can cause nausea or
asphyxiation, severe injury or death from
carbon monoxide and flue gases poison-
ing. Improper installation will void product
warranty.
The vent terminator provides a means of installing vent
pipe through the building wall and must be located
in accordance with CSA-B149.1 and local applicable
codes.
A proper sidewall direct-vent terminator is recommended
when the water heater is vented through a sidewall.
General rules for venting the 520H water heater are:
1. Place the water heater as close as possible to the vent
terminator.
2. The vent collar of the water heater must be fastened
directly to an unobstructed vent pipe or TH-PA01 adap-
tor.
3. Do not weld the vent pipe to the water heater collar.
4. Do not cut the vent collar of the unit.
5. The weight of the vent stack must not rest on the water
heater.
6. The vent must be easily removable from the top of the
water heater for normal service and inspection of the
unit.
7. The water heater vent must not be connected to any
other gas appliance or vent stack.
8. Avoid locating the water heater vent terminator near any
air intake devices. These fans can pick up the exhaust
flue products from the water heater and return them to
the building. This can create a health hazard.
9. Avoid using an oversized vent pipe or using extremely
long runs of the pipe.
10.Locate the vent terminator so that it cannot be blocked
by any debris, at any time. Most codes require that the
terminator be at least 305mm (12 in.) above grade, but
the installer may determine if it should be higher depend-
ing on the job site condition and applicable codes.
11.For rooftop venting, a rain cap or other form of termina-
tion that prevents rain water from entering into the water
heater must be installed.
•
•

10
PVC Venting Illustrations
Horizontal Installation Diagram (With elbow terminations)
Wall
Connection between exhaust
vent collar and PVC piping. See
the next page for instructions.
Vertical Installation Diagram
Roof
Fire stop
Connection between exhaust
vent collar and PVC piping. See
the next page for instructions.
Roof Flashing
Horizontal Installation Diagram (With 76mm (3 in.) PVC
Concentric Termination)
Keep a 25mm (1 in.) clearance between
wall and the intake section of the concentric
termination. See the diagram below.
Wall
Connection between
exhaust vent collar and PVC
piping. See the next page for
instructions.
25mm (1 in.)
min. clearance
Concentric
Termination
Insert the bird
screen included
with the termination.
How to install PVC venting with the 520H (For Exhaust)
1. Connect the TH-PA01 PVC adaptor* directly on the
exhaust vent collar of the water heater.
2. Connect a 102mm (4 in.) PVC coupler (or 4x3" PVC
reducer) to the TH-PA01 PVC adaptor.
3. From the coupler (or reducer), continue on the rest of the
vent run with 102mm (4 in.) PVC pipe (or 76mm (3 in.)
PVC pipe.)
(For Intake: 102mm (4 in.) only)
Connect a 102mm (4 in.) PVC Straight pipe directly on
the intake vent collar of the water heater.
102mm (4 in.)
PVC straight pipe
102mm (4 in.)
PVC straight pipe 102mm (4 in.)
PVC coupler
TH-PA01 PVC
adaptor*
Exhaust vent collar of
the 520H (Female)
Intake vent collar
* TH-PA01 PVC adaptor
is included with the 520H.
1.

11
(For Intake: 76mm (3 in.) only)
Connect a 102mm (4 in.) PVC Straight pipe directly on
the intake vent collar of the water heater.
Connect a 4x3" PVC reducer to the 102mm (4 in.) PVC
Straight pipe.
From the reducer, continue on the rest of the vent run
with 76mm (3 in.) PVC pipe.
76mm (3 in.) PVC
straight pipe
76mm (3 in.) PVC
straight pipe
4x3" PVC
reducer
TH-PA01 PVC
adaptor*
Exhaust vent collar of
the 520H (Female)
Intake vent collar
* TH-PA01 PVC adaptor
is included with the 520H.
4x3" PVC
reducer
1026mm (4 in.)
PVC straight pipe
1.
2.
3.
Stainless steel Venting Illustrations
Horizontal Installation Diagram
Wall
Sidewall Vent
Terminator
Vertical Installation Diagram
Roof
Fire stop
Rain Cap
Roof Flashing
Regarding the clearances from the exhaust terminator to
the air inlet or opening, refer to the next few pages.
Follow all vent system manufacturer’s instructions and
all local codes.
Do not common vent or connect any vent from other
appliances to the 520H water heater vent.
Use 102mm (4 in.) Category III/IV approved or Special
BH, single or double wall stainless steel vent pipe.
•
•
•
•

12
Vent clearances
INSIDE CORNER
DETAIL
FIXED
CLOSED
OPERABLE
FIXED
CLOSED
OPERABLE
Vent terminal
Air supply inlet
Area where is not permitted
Gas meter / regulator
Canada U.S.A
Direct vent and other
than Direct Vent Direct vent Other than Direct Vent
A Clearance above grade, veranda, porch, deck, or balcony. 1 foot 1 foot 1 foot
B Clearance to window or door that may be opened 3 feet 1 foot 4 feet from below or side opening. 1 foot
from above opening.
C Clearance to permanently closed window * * *
DVertical clearance to ventilated soffit located above the vent terminator within a horizontal distance of 2 feet
(61cm) from the center line of the terminator. ***
E Clearance to unventilated soffit * * *
F Clearance to outside corner * * *
G Clearance to inside corner * * *
HClearance to each side of center line extended above
meter/regulator assembly 3 feet * *
I Clearance to service regulator vent outlet. 3 feet * *
JClearance to non-mechanical air supply inlet to building or
the combustion air inlet to any other application 3 feet 1 foot 4 feet from below or
side opening. 1 foot
from above opening.
K Clearance to mechanical air supply inlet. 6 feet 3 feet 3 feet
LClearance above paved sidewalk or paved driveway
located on public property. 7 feet * 7 feet
M Clearance under veranda, porch deck, or balcony. 1 foot * *
* For clearances not specified in CSA-B149.1, please use clearances in accordance with local installation codes and
the requirement of the gas supplier.

13
Additional clearances
Please follow all local and national codes in regards to prop-
er termination clearances. In the absence of such codes,
the following clearances can be used as guidelines. Local
codes supersede these guidelines.
For sidewall terminations
Inside
corner
Exhaust
termination
610mm
(2 ft.)
305mm
(1 ft.)
305mm
(1 ft.)
Inside
corner
610mm
(2ft.)
305mm
(1 ft.)
305mm
(1 ft.)
Direct vent
termination
For multiple sidewall
exhaust terminations (e.g.
multi-unit systems), an
exhaust termination must
be at least 305mm (1 ft.)
away from another exhaust
termination. An exhaust ter-
mination must also be at
least 610mm (2 ft.) away
from an inside corner (if the
adjacent wall is less than
610mm (2 ft.) of length, the
minimum required distance
away from the inside corner
will be equal to the length of
that adjacent wall).
For multiple-unit, direct-
vent sidewall terminations
that combine the intake
and exhaust into a single
penetration, space each
direct-vent termination at
least 305mm (1 ft.) away
from each other, no matter
the orientation. A direct-vent
termination must also be at
least 610mm (2 ft.) away
from an inside corner (if the
adjacent wall is less than
610mm (2 ft.) of length, the
minimum required distance
away from the inside corner
will be equal to the length of
that adjacent wall).
915mm
(3 ft.)
915mm
(3 ft.)
915mm
(3 ft.)
Air supply inlet Exhaust
termination
2 ft.
For direct-vent sidewall ter-
minations that use two sep-
arate penetrations for the
intakeandexhaust,distance
the intake and exhaust ter-
minations at least 915mm
(3 ft.) away from each other,
no matter the orientation.
Exhaust and/or direct-vent
sidewall terminations should
be at least 610mm (2 ft.)
away from an opposite sur-
face/wall. Do not place the
termination directly in front
of an opening into a build-
ing.
For rooftop terminations
A
AA
Air
intake
Exhaust
termination
610mm
(2 ft.)
AA
Exhaust
termination
Air
intake
A: In accordance with local codes
For multiple-unit rooftop terminations (whether for stan-
dard or direct-vent installations) space all exhaust and
intake terminations in accordance with local codes. An
exhaust termination must be spaced from a wall or surface
in accordance with local codes as well. In the absence of
such a code, an exhaust termination must be a horizontal
distance of at least 610mm (2 ft.) away from a wall or
surface.

14
Gas Supply And Gas Pipe Sizing
TO TURN OFF GAS
TO APPLIANCE
Turn off all electric power to the water heater if service
is to be performed.
Turn the manual gas valve located on the outside of
the unit clockwise to the off position.
1.
2.
WARNING
Ensure that any and all gas regulators
used are operating properly and provid-
ing gas pressures within the specified
range shown below. Excess gas inlet
pressure may cause serious accidents.
Conversion of this unit from natural gas
to propane or vise versa will void all
warranty. Contact your local distributor
to get the correct unit for your gas type.
The manufacturer is not liable for any
property and/or personal damage result-
ing from gas conversions.
•
•
*Check that the type of gas matches the rating plate first.
1. The minimum and maximum inlet gas pressures are:
Gas type Inlet gas pressure
Natural Gas Min. 5.0" WC – Max. 10.5" WC
Propane Gas Min. 8.0" WC – Max. 14.0" WC
2. Gas pressure below this specified range for the 520H
and/or insufficient gas volume will adversely affect per-
formance. These pressures are measured when the
520H is in full operation.
3. Inlet gas pressure must not exceed the above maximum
values; gas pressure above the specified range will
cause dangerous operating conditions and damage to
the unit.
4. Until testing of the main gas line supply pressure is com-
pleted, ensure the gas line to the 520H is disconnected
to avoid any damage to the water heater.
Measuring inlet gas pressure
The 520H cannot perform properly without sufficient inlet
gas pressure. Below are instructions on how to check the
inlet gas pressure. THIS IS ONLY TO BE DONE BY A
LICENSED PROFESSIONAL.
Shut off the manual gas valve on the supply gas line.
Remove the screw for the pressure port located on the
gas inlet of the water heater shown in the diagram to the
right.
Connect the manometer to the pressure port.
Re-open the manual gas valve. Check to see that there
are no gas leaks. Open some of the fixtures that use the
highest flow rate to turn on the water heater.
Check the inlet gas pressure. When the water heater is
on maximum burn, the manometer should read from 5.0"
to 10.5" WC for Natural gas, from 8.0" to 14.0" WC for
Liquid Propane.
Pressure
port
Size the gas pipe appropriately to supply
the necessary volume of gas required for
the 520H models (199,000 BTU/h for both
Natural Gas and Liquid Propane) using
CSAB149.1 or local codes. Otherwise, flow
capabilities and output temperatures will be
limited.
Install a manual gas shut-off valve between the water
heater and the gas supply line.
When the gas connections are completed, it is necessary
to perform a gas leak test either by applying soapy water
to all gas fittings and observing for bubbles or by using a
gas leak detection device.
Always purge the gas line of any debris and/or water
before connecting to the gas inlet.
1.
2.
3.
4.
5.
1.
2.
3.

15
Water connections
FOR YOUR SAFETY, READ
BEFORE OPERATING
Do not use this water heater if any part has been sub-
mersed under water. Immediately call a licensed profes-
sional to inspect the water heater and to replace any
damaged parts.
All pipes, pipe fittings, valves and other components,
including soldering materials, must be suitable for pota-
ble water systems.
A manual shut off valve must be installed on the cold
water inlet to the water heater between the main water
supply line and the water heater.
In addition, a manual shut off valve is also recommended
on the hot water outlet of the unit. If the water heater is
installed within, or subjected to, a closed loop water sys-
tem, a thermal expansion tank must be installed.
Before installing the water heater, flush the water line
to remove all debris, and after installation is complete,
purge the air from the line. Failure to do so may cause
damage to the heater.
There is a wire mesh filter within the cold inlet to trap
debris from entering your heater. This will need to be
cleaned periodically to maintain optimum flow.
Water intlet
(Cold) Gas intlet
Condensate
drain port
Water outlet
(Hot)
WARNING
Do not reverse the hot outlet and cold inlet
connections to the 520H Water Heater. This
will not properly active the water heater.
Pressure Relief Valve
The 520H has a high-temperature shut off switch built in as
a standard safety feature (called a Hi-Limit switch) therefore
a “pressure only" relief valve is required.
This unit does not come with an approved pressure relief
valve.
An approved pressure relief valve must be installed on
the hot water outlet.
The pressure relief valve must conform to ANSI Z21.22
or CAN 1-4.4 and installation must follow local code.
The discharge capacity must be at least 199,000 BTU/
h.
The pressure relief valve needs to be rated for a maxi-
mum of 150 psi.
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
The discharge piping for the pressure relief valve must
be directed so that the hot water cannot splash on any-
one or on nearby equipment.
Attach the discharge tube to the pressure relief valve and
run the end of the tube to within 150mm (6 in.) from the
floor. This discharge tube must allow free and complete
drainage without any restrictions.
If the pressure relief valve installed on the 520H dis-
charges periodically, this may be due to a defective ther-
mal expansion tank or defective pressure relief valve.
The pressure relief valve must be manually operated
periodically to check for correct operation.
Hot outlet Cold intlet Gas intlet
As close as
possible
Pressure
Relief Valve
Condensate Drain
The 520H does not include a built-in condensate neutral-
izer cartridge for reducing the pH level of condensate
water. If local codes dictate that condensate must be
neutralized prior to drainage, a condensate neutralizer
must be installed. An accessory Neutralizer assembly is
sold separately.
In the absence of applicable local codes and regulations,
the manufacturer recommends that condensate be dis-
posed of into a standard drain. Connect a drain tube from
the condensate drain port (shown below) located on the
bottom of the water heater to a standard drain.
Follow all code requirements of the local
authority on condensate neutralizers and
whether or not they are required for the
installation.
Condensate
drain port
6.
7.
8.
9.
•
•

16
Condensate Drain Connections
WARNING
Discharge condensate (acidic water) in
accordance with all local codes and com-
mon safety practices.
The 520H models are high efficiency condensing water
heaters that produce condensate (acidic water). The acidic
condensate generated in the secondary heat exchanger can
be neutralized by the Neutralizer accessory.
Case A: If a neutralizer is not required
Connect a 1/2" FPT X 3/8" (or 1/2") HB Adaptor to the
condensate drain port at the bottom of the water heater.
Connect a condensate drain tube to the 1/2" FPT X 3/8"
(or 1/2") HB Adaptor. The manufacturer recommends
the material of the condensate tube be either EPDM or
PVC.
Leave an adequate amount of space between the end
of the drain tube and the actual drain, to facilitate proper
drainage.
1/2"FPT X 3/8"
(or 1/2") HB
Condensate
drain port
Adequate
space
Drain
3/8" or 1/2"
Condensate
drain tube
1.
2.
3.
Case B: If a neutralizer is required (installing
the Neutralizer assembly)
Connect the 1/2" FPT X 3/8" MPTAdaptor to the conden-
sate drain port at the bottom of the water heater.
Connect the Neutralizer to the 3/8" MPT connection of
the adaptors. There is a flow direction indicator on the
neutralizer. Please orient the neutralizer in the proper
direction.
Connect a 1/2" drain tube to the other end of neutral-
izer.
Leave an adequate amount of space between the end
of the drain tube and the actual drain, to facilitate proper
drainage.
1/2"FPT X 3/8"MPT (Included
with Neutralizer accessory)
Condensate
drain port
Adequate
space
Drain
1/2" Condensate
drain tube
3/8"MPT X 1/2"HB (Included
with Neutralizer accessory)
Neutralizer cartridge (Included
with Neutralizer accessory)
1.
2.
3.
4.

17
WARNING
The condensate drain is at atmospheric
pressure (non-pressurized) and there-
fore must be allowed to drain freely with
gravity only. Please ensure that there
are no blockages along the condensate
drain tube. All portions of the conden-
sate drain (neutralizer and drain tube)
must be at a lower elevation than the
520H to prevent condensate water from
building up inside the heat exchanger.
Condensate cannot be effectively neu-
tralized if the neutralizer elements inside
the Neutralizer accessory have been
completely consumed. If this happens,
Condensate will remain acidic and can
possibly cause damage to items such as
pipes, concrete, etc., if drained improp-
erly.
The Neutralizer cartridge is designed
to last for 3 years before replacement.
However, the actual life of the neutralizer
may vary, depending on the applica-
tion and usage. Please ensure that the
cartridge is properly replaced before the
neutralizer elements have been com-
pletely consumed.
All preventative measures and safety
practices must be adhered to when
draining condensate. The manufacturer
will not be responsible for any damage
caused by condensate.
Adrain pan, or other means of protection
against water damage, is required to be
installed under the water heater in case
of leaks.
•
•
•
•
•
Electrical Connections
WARNING
Follow the electrical code requirements of
the local authority having jurisdiction. In
the absence of such requirements, follow
the latest edition of CSA C22.1 Canadian
Electrical Code, Part 1.
CAUTION
When servicing or replacing parts within the
520H, label all wires prior to disconnection
to facilitate an easy and error-free recon-
nection. Wiring errors can cause improper
and dangerous operation. Verify proper
operation after servicing.
1. The 520H must be electrically grounded. Do not attach
the ground wire to either the gas or the water piping.
2. The 520H requires 120 VAC / 60 Hz electrical power sup-
ply that is properly grounded.
A proper disconnect (i.e. on/off switch, power plug,
etc.) controlling the main power to the water heater
must be provided for service reasons. (Must comply
with local codes).
Connect the power supply to the water heater exact-
ly as shown in the wiring diagram;
3. A green screw is provided in the junction box to ground
the connection.
4. Can be hardwired or wired to a plug-in.
5. The use of a surge protector is recommended in order to
protect the unit from power surges.
Ground
Connect Power supply
120 VAC / 60 Hz
•
•

18
Remote Controller Connection
Disconnect power supply from the water heater.
Take off the water heater’s front cover.
Locate the remote controller terminal, pictured below
(located around the upper right-hand side of the com-
puter board).
Open the plastic cover of the remote controller acces-
sory, and then attach the two fork terminals to connec-
tor base of the backside the controller with two screws.
Make sure the terminals are firmly fixed.
Pull the remote’s wires through the rubber grommet at
the bottom of the water heater’s casing.
1.
2.
3.
4.
5.
Properly attach the remote’s wires to the remote con-
troller terminal on the computer board. (No polarity)
*Do NOT jump or short-circuit the wires or computer will
be damaged.
Replace Front Cover securely.
Wires used for the remote controller connection must
be:Minimum 18AWG wire (No polarity)
Maximum 400 feet long
*For detailed connection instructions to the remote control-
ler accessory, refer to the remote controller’s Installation
Manual.
6.
7.
8.
•
•
Remote controller terminal of the 520H Front of remote Back of remote
Connect other end
to these terminals
Connect to
these terminals

19
Pump Control Connection
The 520H model can be used to control a recirculation
pump. Proper pump control helps to preserve the life of the
system and saves energy as well: The water heater pump
control port is a “normally open dry contact", and therefore
needs additional components to properly control a recircu-
lation pump. To control a recirculation pump, connect the
pump to the “Pump connector" in the 520H as shown in the
diagram below. (In an Easy-Link system, connect the pump
ONLY to the “PARENT" unit.) The pump is to be connected
using suitable relays shown in the diagram below. Please
make sure the relays are properly rated for the recircula-
tion pump. Using the 520H models internal thermistors as a
temperature control, the recirculation pump will only turn on
when recirculation is needed.
CAUTION
In an Easy-Link system, the pump must
be connected to the “Pump connector"
in the “PARENT unit" only. If the pump is
connected to any of the “CHILD units", the
pump will not work.
Recirculation
pump
Connect to this
“Pump connector"
Power supply
for relay
Power supply
for pump
120 VAC
220 VAC etc
120 VAC
220 VAC etc
for relay
Thermal
relay
These components
are NOT included
with the water
heater and are
external to the
unit. They must be
acquired separately.
Pump Control Modes
The 520H provides the four types of the pump control
modes. The pump control modes are selected by changing
DIPswitch settings. The DIPswitches that change the pump
control modes are located in the right bank of DIPswitches
in the upper-left quadrant of the computer board in the
520H. (see below.) These 4 modes only affect pumps that
are connected to the 520H pump control (pg. 19)
Right bank of
DIPswitches
A) Recirculation Control: No. 5 ON
Feature: Maintaining temperature in a standard recircula-
tion loop, providing hot water in a quicker amount
of time.
Function: The pump is only set to run when the tempera-
ture of the water in the recirculation loop is more
than 5C° (9F°) below the set temperature of the
water heater. The pump will run for about 1 min-
ute every 30 minutes to determine whether the
water temperature in the entire recirculation loop
is more than 5C° (9F°) below the set temperature.
If the water temperature is more than 5C° (9F°)
below the set temperature, the pump will remain
running until the water in the loop reaches the
set temperature. Otherwise, the pump will stop
for another 30 minutes. If the inlet thermistor of
water heaters detects that the water temperature
is more than 5C° (9F°) below the set temperature
before those 30 minutes have elapsed, the pump
will activate immediately and remain running until
the water in the loop reaches the set tempera-
ture.
B) Storage Tank Circulation Control: No.6 ON
Feature: This is to ensure a higher rate of recovery for
storage tank applications.
Function: The 520H heats the water 3°C (5.4F°) higher
than its set temperature. The circulation pump
between the storage tank and the water heater
will continually remain running. After set temper-
ature has been reached in the storage tank, the
520H will fire off and limit the water flow rate to
less than 9.8 l/min (2.6 GPM (US)), to continually
monitor the temperature throughout the system.
Note: In this mode, the pump will continually remain
running.

20
C) Energy Conserving Recirculation: No.5 and
No.6 ON
Feature: Operates similarly to the standard Recirculation
Control mode, but saves more energy by limiting
the temperature within the recirculation loop.
Function: The temperature of the recirculation loop is never
kept above 49 °C (120°F), regardless of the set
temperature of the water heater.
D) Normal Control (Default setting): No.5 and
No.6 OFF
Feature: This mode provides no special pump control.
Pump activation can only be turned ON or OFF
by the remote controller.
Function: The pump will run continually all the time as long
as there is a power supply to the water heater.
The pump will only stop when the remote is
turned off. Water in the loop will be maintained at
the set temperature of the water heater.
Dipswitch settings for the Pump control modes (ight bank of
DIPswitches).
Pump
mode
A)
Re-
circulation
Control
B)
Storage
Tank
Circulation
Control
C)
Energy
Conserving
Re-
circulation
D)
Normal
Control
(Default)
Switch
No.5 ON OFF ON OFF
Switch
No.6 OFF ON ON OFF
10
9
8
7
6
5
4
3
2
1
ON
10
9
8
7
6
5
4
3
2
1
ON
10
9
8
7
6
5
4
3
2
1
ON
10
9
8
7
6
5
4
3
2
1
ON
The dark squares indicate the direction the DIPswitch
should be set to.
Easy-link System
General
The 520H can be connected with other heaters of the same
model with communication cables to work as a multiple-unit
manifold system.
The Easy-Link system allows up to 4 units to manifold
together.
A communication cable (gray color) comes with each
unit.
You can manifold from 2 to 4 units without the need for
a multi-system controller. A 4-unit system has full auto-
matic modulation between 13,000 BTU/h and 796,000
BTU/h.
Gas In
Cold In
Hot Out
CAUTION
The Easy-Link system is limited up to 4
units. If you connect more than 4 units,
only the first 4 units will work as a part
of the Easy-Link system. The other addi-
tional units will not work.
The 520H cannot be linked with other
different tankless models in an Easy-
Link system.
•
•
Easy-Link Connection Procedures
Verify the set temperatures of all units within the system.
Every single water heater must be set to the same set
temperature.
Select one unit to be the “PARENT" unit.
“PARENT" unit. Locate the two banks of DIPswitches
to the left of the 3-digit 7-seg. LED on the computer
board of the 520H that you select to be the “PARENT"
unit. Change DIPswitch No. 10 on the right bank of
DIPswitches to the ON position. Do not change any
DIPswitches on any of the “CHILD" units.
Betweenthe“PARENT"andthe“CHILD-1"units.Connect
the “PARENT connector" of the “PARENT" unit to the “[1]
connector" of the “CHILD-1" unit.
Betweenthe “CHILD-1"andthe “CHILD-2"units. Connect
the “[2] connector" of the “CHILD-1" unit to the “[1] con-
nector" of the “CHILD-2" unit.
Betweenthe “CHILD-2"andthe “CHILD-3"units. Connect
the “[2] connector" of the “CHILD-2" unit to the “[1] con-
nector" of the “CHILD-3" unit.
•
•
•
1.
2.
3.
4.
5.
6.