Paloma PH-28RIFSN, PH-28ROFN, PH-28CIFSN, PH-28ROFP, PH-28COFN Engineering Handbook

R

Tankless Gas Water Heaters

PH-28RIFSN; PH-28CIFSN (Indoor) (NAT. Gas)
PH-28RIFSP; PH-28CIFSP (Indoor) (L.P. Gas)
PH-28ROFN; PH-28COFN (Outdoor) (NAT. Gas)
PH-28ROFP; PH-28COFP (Outdoor) (L.P. Gas)
PH-28RDVSN; PH-28CDVSN (Direct Vent) (NAT. Gas)
PH-28RDVSP; PH-28CDVSP (Direct Vent) (L.P. Gas)
(R: Residentail Model; C: Commercial Model)

Engineering Handbook

D

E

S

I

G

N

C

E

R

T

I

F

I

E

D

®

CERTIFIED

R

Indoor W ater Heater

Outdoor W ater Heater

Direct Vent Water Heater

- Do not store or use gasoline or other flammable vapors and liquids in the
vicinity of this or any other appliance. To do so may result in an explosion or fire.

- WHAT TO DO IF YOU SMELL GAS
* Do not try to light any appliance.
* Do not touch any electrical switch; do not use any phone in your building.
* Immediately call your gas supplier from a neighbor's phone. Follow the gas
supplier's instructions.
* If you cannot reach your gas supplier, call the fire department.
* Do not return to your home until authorized by the gas supplier or fire department.

- Installation and service must be performed by a qualified installer, service
agency or the gas supplier.

WARNING: If the information in these instructions is not followed
exactly, a fire or explosion may result causing property damage,
personal injury or death.

WARNING: Improper installation, adjustment, alternation, service or maintenance
can cause property damage, personal injury, or death. For assistance or additional
information, consult with a qualifi ed distributor.

WARNING: The content on this manual is intended for use by qualifi ed service
personnel ONLY.

Table of Contents

- 2 -

Page

Specifi cations ................................................................. 3

External Dimensions ...................................................... 4 ~ 5

Schematic Construction ................................................. 6 ~ 8

Operational Principle ..................................................... 9 ~ 12

Capacity ......................................................................... 13 ~ 14

Wiring Diagram ............................................................. 15

Operational Flow Chart & Maintenance Information.... 16

Diagnostic Points ........................................................... 17 ~ 22

Hints for Diagnosis ........................................................ 23 ~ 34

Adjustment ..................................................................... 35 ~ 47

How to Disassemble Each Parts ..................................... 48 ~ 52

Schematic Disassembly and Parts List .......................... 53 ~ 67

SPECIFICATIONS (Approx.)

Model PH-28RIFSN (NAT)

PH-28RIFSP (L.P.)
PH-28CIFSN (NAT)
PH-28CIFSP (L.P.)

PH-28ROFN (NAT)
PH-28ROFP (L.P.)
PH-28COFN (NAT)
PH-28COFP (L.P.)

PH-28RDVSN (NAT)
PH-28RDVSP (L.P.)
PH-28CDVSN (NAT)

PH-28CDVSP (L.P.)
Purpose Domestic Hot Water Supply & Circulating
Rated Gas Input

(Btu/Hr.)

19,000 (Min.)
199,900 (Max.)(Modulating)

19,000 (Min.)
199,900 (Max.)(Modulating)

19,000 (Min.)

199,900 (Max.)(Modulating)
Dimensions (in.) 14 7/8 (W) x 25 3/8 (H) x 11 1/8 (D)
Net Weight (lbs.) 65
Installation Indoor W all Mounting Type

Can be vented either hori­zontally or vertically

Outdoor W all Mounting
Type

Direct Vent Indoor W all

Mounting Type

Can be vented either hori-

zontally or vertically
Working Water Pressure 14 psi ~ 150 psi
Minimum Water Flow 0.66 GPM
Maximum Flow Rate 7.4 GPM at 45ºF Temperature Rise
Gas Connection 3/4” NPT Female (w/supplied Gas Shutoff Valve)
Water Connection 3/4” NPT Male
Vent Size 4” Special Venting

(Category III)

N/A (Outdoor Installation) 4” Special Venting

(Category III)
Max. Vent Length 37.5 Feet Three 90º Elbow N/A (Outdoor Installation) 37.5 Feet Three 90º Elbow
Effi ciency Rating 84%
Energy Factor 0.82
Inlet Gas Pressure

before water heater

Natural Gas: Min. 4.0” w.c. Max. 10.5” w.c.
L.P. Gas: Min. 8.0” w.c. Max. 14.0” w.c. (Do not exceed maximum pressure.)

Hot Water Supply Factory Setting 100ºF

Adjusting Range R:100ºF ~ 120ºF (140ºF); C: 100°F ~ 180°F
Max. Setting Up to 140ºF(R) or 180°F(C)(w/ Main Remote Control &

Dip Switch Adj.)

Electrical Portion Electrical Rating 120VAC/60Hz, Less than 2 Amps

Power Supply Cord 3 Pin Power Supply Cord 10 Feet (Indoor & Direct Vent)

Safety Devices Oxygen Depletion Safety Sensing Burner (Indoor & Direct Vent)

Over Heat Limiter Film Type for Entire Heat Exchanger

Flame Failure Safety Flame Rod Type
Freeze Protection Minus 30ºF (Without Wind-Chill Factor)
Optional Accessory First Bath Remote Control (USC1-117); Second Bath Remote Control (USC2-117)

DUOnex ™ for 2-Unit Manifolding

MIC-180 for Multi-Unit System Controller (2 to 6 units); MICS-180 for Expansion Board

(Up to 20 units); MIC Communication Cables (16, 32 & 65 feet)

High Altitude Adjustment Chips for use at altitudes above 3,280 feet, and up to 9.840 feet

Hot Water Flow Rate and Temperature Rise
Temp. Rise (ºF) 45 50 60 70 80 90 100
Water Flow (GPM) 7.4 6.7 5.6 4.8 4.2 3.7 3.4

- 3 -

Note: Special Venting: The adapter, vent pipe, elbow, vent terminal, etc. Should be UL 1738 Certifi ed Category III Stainless
Steel Venting Material (e.g. AL29-4C). “B” vent is not permitted.
Since we are constantly improving our products, all specifi cations are subject to change without notice.

EXTERNAL DIMENSIONS

(PH-28RIFS & PH-28CIFS Indoor Model)

- 4 -

(PH-28ROF & PH-28COF Outdoor Model)

POWER SUPPLY CORD HOLE

COLD WATER INLET

6.34” (161mm)

6.34” (161mm)

8.39” (213mm)

4.69” (119mm)

14.96” (380mm)

5.12” (130mm)

3.45”(87mm)

HOT WATER OUTLET

1.93” (49mm)

5.51”
(140mm)

2.52”
(64mm)

4.17” (106mm)

GAS INLET

1.57”6.81” (173mm)

5.79” (147mm)

WIRING HOLE

25.39” (645mm)

27.36” (695mm)

1.89” (48mm)

1.97” (50mm)

Ø4” (101.6mm)

11.10” (282mm)

0.39” (10mm)

3/4"NPT(M)

3/4"NPT(M)
(W/Supplied Gas Shutoff Valve)

3/4"NPT(M)

(40mm)

0.59” (15mm)

0.59” (15mm)

8.17”(207mm)

8.82”(224mm)

2.13” (54mm)

0.73”

(18.5mm)

25.39” 645mm)

27.36” (695mm)

26.46” (672mm)

0.33”

(8mm)

1.89”

(48mm)

1.97”

(50mm)

6.30” (160mm)

6.10” (155mm)

8.39” (213mm)

4.69” (119mm)

5.51”
(140mm)

2.52”
(64mm)

4.17”
(106mm)

5.79” (147mm)

6.81” 173mm)

14.29” (363mm)

1.97”

(50mm)

1.57”

(40mm)

1.93” (49mm)

1.73” (44mm)

3.19”

(81mm)

14.96” (380mm)

3.54” (90mm)

5.12” (130mm)

WIRING HOLE

POWER SUPPLY CORD HOLE

COLD WATER INLFT

HOT WATER OUTLET

GAS INLET

0.43”
(11mm)

9.02’ (229mm)

9.02” (229mm)

11.10” (282mm)

0.39”
(10mm)

3/4"NPT(M)

3/4"NPT(M)
(W/Supplied Gas Shutoff Valve)

3/4"NPT(M)

EXTERNAL DIMENSIONS

(PH-28RDVS & PH-28CDVS Direct Vent Model)

- 5 -

(Remote Control)

COMBUSTION
INDICATOR

POWER ON/OFF
INDICATOR

POWER ON/OFF
BUTTON

PRIORITY INDICATOR

TEMPERATURE
ADJUSTMENT
BUTTON

LED DISPLAY

POWER

ON/OFF

PRIORITY

°

F

7/8” (21mm)

4 3/4” (120mm)

4 3/4” (120mm)

1 7/8” 46mm)

3 1/4” (83.5mm)

6.34” (161mm)

POWER SUPPLY CORD HOLE

COLD WATER INLFT

6.34” (161mm)

8.39” (213mm)

4.69” (119mm)

5.51”
(140mm)

HOT WATER OUTLET

3.45

1.89” (48mm)

27.36” (695mm)

25.39” (645mm)

14.96” (380mm)

5.12”
(130mm)

5.12” (130mm)

2.52”
(64mm)

4.17”
(106mm)

GAS INLWR

1.576.81” (173mm)

5.79” (147mm)

1.93” (49mm)

WIRING HOLE

1.97” (50mm)

0.39” (10mm)

11.10” (282mm)

Ø4” (101.6mm)

3/4"NPT(M)

3/4"NPT(M)
(W/Supplied Gas Shutoff Valve)

3/4"NPT(M)

SCHEMATIC CONSTRUCTION

- 6 -

No. Name of Parts No. Name of Parts No. Name of Parts

1 Front Cover 11 Sensing Burner Assembly 21 Water Inlet Connection
2 Back Cover 12 Orifi ce Stand L Assembly 22 Hot Water Outlet Connection
3 Air Filter Assembly 13 Orifi ce Stand R Assembly 23 Drain Valve
4 Exhaust Flue Top 14 Electrode 24 Water Control Body Assy.
5 Heat Exchanger 15 Fan Assembly 25 PC Board
6 Heat Transfer Coil 16 Gas Control V alve Assembly 26 Film Type OHL
7 Water Supply Coil 17 Water Supply Pipe
8 Turbulence Plate 18 Hot Water Supply Pipe
9 Inner Case 19 Bypass Pipe

10 Main Burner 20 Gas Connection

(PH-28RIFS & PH-28CIFS Indoor Model)

1

4

2

19

12

17

18

26

6

8

5

7

10

14

11

13

9

15

3

16

20

21

23

22

24

25

Hot Water Outlet
Connection 3/4” NPT (M)

Water Inlet Connection
3/4” NPT (M)

Gas Connection 3/4” NPT (F)
(W/Supplied Gas Shutoff Valve)

- 7 -

SCHEMATIC CONSTRUCTION

(PH-28ROF & PH-28COF Outdoor Model)

No. Name of Parts No. Name of Parts No. Name of Parts

1 Front Cover 11 Orifi ce Stand L Assembly 21 Hot Water Outlet Connection
2 Back Cover 12 Orifi ce Stand R Assembly 22 Drain Valve
3 Rain Cover 13 Electrode 23 Water Control Body Assy.
4 Flue Outlet 14 Fan Assembly 24 PC Board
5 Heat Exchanger 15 Gas Control Valve Assembly 25 Film Type OHL
6 Heat Transfer Coil 16 Water Supply Pipe
7 Water Supply Coil 17 Hot Water Supply Pipe
8 Turbulence Plate 18 Bypass Pipe
9 Inner Case 19 Gas Connection

10 Main Burner 20 Water Inlet Connection

14

22

5

19

12

7

20

2

24

15

3

11

6

8

25

18

13

1

23

9

4

17

21

16

10

Hot Water Outlet
Connection 3/4” NPT (M)

Water Inlet Connection
3/4” NPT (M)

Gas Connection 3/4” NPT (F)
(W/Supplied Gas Shutoff Valve)

- 8 -

SCHEMATIC CONSTRUCTION

No. Name of Parts No. Name of Parts No. Name of Parts

1 Front Cover 11 Orifi ce Stand L Assembly 21 Hot Water Outlet Connection
2 Back Cover 12 Orifi ce Stand R Assembly 22 Drain Valve
3 Air Intake 13 Flame Rod 23 Water Control Body Assy.
4 Exhaust Flue Top 14 Fan Assembly 24 Film Type OHL
5 Heat Exchanger 15 Gas Control Valve Assembly 25 Sensing Burner Assembly
6 Heat Transfer Coil 16 Water Supply Pipe 26 Burner Rod
7 Water Supply Coil 17 Hot Water Supply Pipe
8 Turbulence Plate 18 Bypass Pipe
9 Inner Case 19 Gas Connection

10 Main Burner 20 Water Inlet Connection

(PH-28RDVS & PH-28CDVS Direct Vent Model)

6

2

5

1

8

7

4

3

9

10

11

12

14

15

16

17

18

19

20

21

22

23

24

25

26

13

- 9 -

OPERATIONAL PRINCIPLE

No. Name of Parts No. Name of Parts No. Name of Parts

1 Hot W ater Tap 11 Solenoid Valve 2 21 Exhaust Outlet
2 Bypass Solenoid Valve 12 Solenoid Valve 3 22 Combustion Chamber
3 Water Flow Sensor 13

Proportional Gas Control Valve

23 Freeze Protection Heater
4 Water Inlet Thermistor 14 Orifi ce 24 Fan
5

Heat Exchanger Thermistor

15 Main Burner 25 Fan Motor

6

Hot W ater Outlet Thermistor

16 Igniter 26 Drain Valve
7 Water Flow Servo 17 Electrode 27 PC Board
8 Water Filter 18 Flame Rod
9 Gas Inlet Solenoid Valve 19 Heat Exchanger

10 Solenoid Valve 1 20 Film Type OHL

M

M

Hot Water
Outlet

Gas
Inlet

21

19

14

15

16

18

22

20

23

27

25

24

5

17

7

2

4

3

8

1

26

6

13

9

12

10

11

Water
Inlet

- 10 -

OPERATIONAL PRINCIPLE

WHEN SUPPLYING HOT WATER

1) By opening the Hot Water Top (1), the water fl ows through the Water Flow Sensor (3) to the Heat
Heat Exchanger (19).

2) The frequency signal is given from the Water Flow Sensor (3) and when the PC Board (27) senses the signal
that reached a certain frequency, the Fan (24) starts to turn round.

3) After the Fan (24) turned round and pre-purged, the Gas Inlet Solenoid Valve (9), Solenoid Valve 1 (10) and
Solenoid Valve 2 (11) open at the same time. Then, the Proportional Gas Control Valve (13) becomes an
ignition motion and allows the gas to fl ow to the Main Burner (15) (and Sensing Burner for PH-28RIFS,
PH-28CIFS, PH-28RDVS and PH-28CDVS only).

4) At the same time, the Igniter (16) continuously makes sparks and ignites the Main Burner (15).
After ignited, when the Flame Rod (18) senses the fl ame and make sure the combustion, the Proportional
Gas Control Valve (13) fi nishes the ignition motion.

5) After fi nished the ignition motion, the proportional gas control is started. When there is a temperature
difference between the hot water temperature that is sensed by the Hot Water Outlet Thermistor (6) and the
set temperaturer on the Remote Control, the PC Board (27) judges it and open or close the Solenoid
Valve 1 (10), Solenoid Valve 2 (11) and Solenoid Valve 3 (12), and also the Proportional Gas Control Valve
(13) continuously adjusts the gas volume in order to maintain the outlet temperature from the Heat
Exchanger (19).
The Water Flow Servo (7) also adjusts the proper amount of water fl ow to supply a stable hot water
temperature at all times.

6) According to the adjustment of the gas volume by the Proportional Gas Control Valve (13), a signal from the
PC Board (27) is also sent to the Fan Motor (25) in order to maintain the relation between the gas volume
and air volume at all times.

7) (For PH-28RIFS, PH-28CIFS, PH-28RDVS and PH-28CDVS only) When the air intake or venting is
blocked, or the oxygen of the air intake is not suffi cient, the output of the Thermocouple that is located at the
Sensing Burner would be changed. The PC Board (27) senses this change and controls the Fan (24),
Proportional Gas Control Valve (13), etc. in order to prevent the imperfect combustion. Further, if such
condition is proceeded, it shuts off the Gas Inlet Solenoid Valve (9), Solenoid Valve 1 (10),
Solenoid Valve 2 (11), Solenoid Valve 3 (12) and Proportional Gas Control Valve (13) in order to stop the
operation.

8) When the Hot Water Tap (1) is closed, the frequency signal from the Water Flow Sensor (3) is stopped and
the Gas Inlet Solenoid Valve (9), Solenoid Valve 1 (10), Solenois Valve 2 (11), Solenoid Valve 3 (12) and
Proportional Gas Control Valve (13) turn off and becomes a post-purge motion.

9) When the time of the post-purge is up, the Fan (24) stops.

- 11 -

[Sensing Burner]

The sensing burner is a all primary air type ceramic burner that consists of an outer jacket surrounding the flame
opening and a thermocouple to detect flame temperature. In case oxygen level decreases due to blocked or
clogged air intake or flue venting, or by contaminated air, location of the flame will change as well as its
temperature by the thermocouple. The sensing burner is located in the part of the main burner and designed to
monitor the flame condition at all times. Therefore, it shut off gas before the imperfect combustion occurs in the
main burner.

Oxygen Depletion Safety Device (O.D.S.D.)

NORMAL

========

BLOCKING LACK OF OXYGEN

The flame lifts away
from the thermocouple.

The flame lifts away
from the thermocouple.

(Blocked or clogged vent, fan etc.)

(Contaminated air in room, etc.)

========================

ThermocoupleThermocouple Thermocouple

Primary Air

Primary Air Primary Air

(Lack of Oxygen)

Secondary Air

Gas

Gas

Gas

(Decrease)

(Indoor Model & Direct Model Only)

- 12 -

If Imperfect Combustion Happens.....

Ignition

Normal Air
Flow Rate

Extinction
Post- Purging

Sensor Stand-By
Lead Time

Cold: 2 Min.
Hot: 30 Sec. - 1 Min.

Water Flow
Servo OFF

Decrease of Thermo
Electric Current

Input Down
(Increase Air
Flow Rate)

Automatic Control To Resolve
Imperfect Combustion

Decrease of Thermo
Electric Current

Primary Warning
(Light)

Decrease of Thermo
Electric Current

Decrease of Thermo
Electric Current

Secondary Warning

(Alarm + Light)

Shut Down
(After- Purging)

Monitor Code

No Error
Code

Both Red and Green
flashing at the same time

05

Both Red and Green
flashing at the same time

Every 60 seconds, you hear
noticing alarm (Beep sound).

Monitor Code

Monitor Code

6 times

13

Only Red lamp flashing

(Indoor Model &
Direct Model Only)

(Display on Remote Control)

NOTE: Shutdown by impeefect combustion can be reset by pressing power switch (ON/OFF Button).
However, if it occurs 5 times within 4 hours, the water heater will not recover for the next 4 hours.

- 13 -

Capacity

Hot Water Capacity Curve: Residential Models

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 40°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

0.66
GPM

7.4

GPM

When maximum temperature is set at 140°F

When maximum temperature is set at 120°F

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 50°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

When maximum temperature is set at 140°F

When maximum temperature is set at 120°F

0.66
GPM

7.4

GPM

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 60°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

When maximum temperature is set at 140°F

When maximum temperature is set at 120°F

0.66
GPM

7.4

GPM

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11. 0

100

110

120

130

140

Inlet Water Temperature : 70°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

When maximum temperature is set at 140°F

When maximum temperature is set at 120°F

0.66
GPM

7.4

GPM

Water Flow Rate (GPM)

Water Pressure (psi)

4.3

4.8

5.3

5.8

6.4

6.9

7.4

Inlet Water Temperature: 70

°F

Inlet Water Temperature: 40

°F

(7.4)

(4.8)

14 30 45 60 105 120

135

(At The Outlet Hot Water Temperature : 110 )

°F

Water Pressure & Water Flow Rate:

- 14 -

Capacity

Hot Water Capacity Curve: Commercial Models

Water Flow Rate (GPM)

Water Pressure (psi)

4.3

4.8

5.3

5.8

6.4

6.9

7.4

Inlet Water Temperature: 70

°F

Inlet Water Temperature: 40

°F

(7.4)

(4.8)

14 30 45 60 105 120

135

(At The Outlet Hot Water Temperature : 110 )

°F

Water Pressure & Water Flow Rate:

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 40°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

0.66
GPM

7.4

GPM

150

160

170

180

When maximum temperature is set at 180°F

When maximum temperature is set at 120°F

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 50°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

0.66

GPM

7.4

GPM

When maximum temperature is set at 180°F

When maximum temperature is set at 120°F

150

160

170

180

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

100

110

120

130

140

Inlet Water Temperature : 60°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

150

160

170

180

0.66
GPM

7.4

GPM

When maximum temperature is set at 180°F

When maximum temperature is set at 120°F

0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11. 0

100

110

120

130

140

Inlet Water Temperature : 70°F

Water Flow Rate (GPM)

Outlet Temperature (°F)

150

160

170

180

0.66
GPM

7.4

GPM

When maximum temperature is set at 180°F

When maximum temperature is set at 120°F

- 15 -

Wiring Diagram

B

8

R GR Y B O

W

BR

AIR

INTAKE

FILTER

SWITCH

TRANSFORMER

GND

BK

GND

WATER

FLOW

SENSOR

OVER HEAT

LIMITER

BK:BLACK

COLOUR CODE

BR:BROWN

R:RED

W:WHITE

B:BLUE

GY:GRAY

GR:GREEN

O:ORANGE

Y:YELLOW

G/Y:GREEN/YELLOW

REMOTE

REMOTE

REMOTE

(UMC-117)

(USC1-117)

(USC2-117)

FAN

MOTOR

FM

5

WIRING DIAGRAM

FUSE(3A)

CIRCUIT

BOARD

SV3 SV2

SV1

SV0

W B R O Y

W

W

CONNECTOR FOR CHECKING

THERMOELECTROMOTIVE FORCE

FUSE

(5A)

2

1

U

2

1

O

S

1 3 2

B

R

GR

Y B O

W

R1

BR

R2

R3 R4

GR

GR

GY

GY

W Y R

R

R

BR

B Y

W

R

W W R

W

BK

BK

BK

BK

BK

BK

BK

BK

BK

BK BK

BK

BK

W

BK

IGNITER

ELECTRODE

W

1

2

3

4

5

6

7

1

2

1

2

8

1
2
3
4

Q

P

R

1

2

3

4

5

6

1

2

3

4

5

6

7

OFF

ON

1

2

3

4

I

J

H

F

D E

B

A

PSV

M

L

-

+

K

G

T

CONTROL MOTOR

WATER VOLUME

LIMITER

MOTOR

SW2

SW1

SW3

R

R

G/Y

BK

W

AC

100V

G/Y

W

AC

120V

FOR INDOOR

MODEL ONLY

1
4

5

6 3

2

3

6

5
2

1

4

IG

WV

B

DIP SWITCH

ADJUSTER

BUTTON

MIN

BUTTON

MAX

BUTTON

MAIN

WATER BY-PASS

SOLENOID VALVE

V A

L V E 3

S

O L E N O I D

V A

L V E 2

S

O L E N O I D

V A

L

V E

1

S

O L E N O I D

V A

L V E

0

S

O L

E

N O

I

D

G

A S

I

N

L

E

T

T

H

E R M

I

S

T

O

R

A

I

R

A

M B

I

E N

T

T

H

E R

M

I S

T

O

R

I

N

L E T

W

A

T

E R

T

H E R M

I

S T

O

R

E

X C H A N

G

E

R

H

E A

T

T

H

E R

M

I S

T

O R

H

O T W

A

T

E R

O

U

T

L E

T

V A

L

V E

FROST

PROTECTION

THERMOSTAT

W W

W

W

W

BK

BK

BK

BK

BK

W W

W

W

W

BK

FOR INDOOR

MODEL ONLY

ANTI-FROST

HEATER

T

H

E

R

M

O

C O U

P

L

E

(BLUE)

(RED)

(RED)

R

W

CONTROL

BATH

BATH

CONTROL1

CONTROL2

LED

FLAME ROD1

FLAME ROD2

FLAME ROD3

THE CONNECTORS OF DUAL AND MULTIPLE

ARE INTERAPPLICABLE TO THE BODY

CONNECTORS EACH OTHER.(RED)

A wiring diagram is also located on the inside of the front cover panel.
Slightly different by model and serial number.

Operational Flow Chart & Maintenance Information

- 16 -

Diagnostic Points

- 17 -

The voltage showed is the value of operating condition when the water heater operates according to the flow chart.
The resistance showed is the value of load side when turned off the electric power and disconnected the connector.

k

5

- 18 -

MAINTENANCE INFORMATION SHOWN IN LED DISPLAY OF REMOTE CONTROL

ABOVE

- 19 -

- 20 -

Error Codes

Code Fault Remedy

05 Imperfect Combustion Alarm Clean air inlet fi lter.

Clean combustion air fan.
Clean heat exchanger fi ns.
Check for adequate combustion air ventilation openings and clean if neces­sary.
Check vent system for partial blockage and correct as necessary.

10 Decrease of Fan Motor Ventilation

Amount
Air Supply or Exhaust Blockage
(Warning)

Check all vent components for proper connections.
Check that nothing is blocking the fl ue inlet or exhaust.
Ensure condensation trap/drain was installed correctly.
Ensure heat exchanger fi ns, fan, and air intake are not blocked.

11 Ignition Failure

No Ignition

Ensure you have gas to the appliance and valves are turned ON.
Ensure gas type and pressure is correct.
Bleed all air from gas lines.
Ensure gas line, meter, and regulator are sized properly.
Ensure appliance is properly grounded.
Check gas solenoid valves for open or short circuits.
Ensure igniter is operational.
Check igniter wiring harness for damage.
Ensure maximum vertical vent length does not exceed allowable limits.
Ensure total maximum vent length does not exceed allowable limits.

12 Flame Failure Ensure you have gas to the appliance.

Ensure gas type and pressure is correct.
Bleed all air from gas lines.
Ensure fl ame rod wire is connected.
Check fl ame rod for carbon build-up.
Ensure gas line, meter, and regulator are sized properly.
Ensure appliance is properly grounded.
Check gas solenoid valves for open or short circuits.
Check power supply for proper voltage and voltage drops.
Disconnect remote control; if it runs.
Disconnect and re-connect all wiring harnesses on unit and PC board.
Ensure proper venting material was installed.
Ensure maximum vertical vent length does not exceed allowable limits.
Ensure total maximum vent length does not exceed allowable limits.

13 Oxygen Depletion Sensor (O.D.S.)

Working (Poor or Improper Com­bustion)

Ensure there is plenty of fresh air to the unit.
Unit needs 1 square inch (6.5 cm2) for each 1,000 BTU of input.
Check for a foreign materials in combustion chamber and/or O.D.S. De­vice.

14 Over Heating Ensure high fi re and low fi re manifold pressure is correct.

Check gas type of unit and ensure it matches gas type being used.
Check heat exchanger for cracks and/or separations.
Check for restrictions in airfl ow around unit and vent terminal.
Check for a foreign materials in combustion chamber and/or exhaust pip­ing.
Check for clogged heat exchanger (scale buildup).

- 21 -

Code Fault Remedy

15 Boiling Safety Device Check for closed water heater inlet valve or restriction in cold water inlet

pipe (must be fully open).
Check for clogged heat exchanger (scale buildup).
On commercial water heater, lower set point temperature below 180F at
high altitude.

16 Outlet Water Temperature Too High

Over Temperature Warning

Check for clogged heat exchanger (scale buildup).
Check for restrictions in airfl ow around unit and vent terminal.
Check for a foreign materials in combustion chamber and/or exhaust pip­ing.

21 Malfunction of Air Intake

Filter Switch

Make sure air fi lter door is properly seated.
Make sure front panel is properly installed.

24 Malfunction of Operational Switch Disconnect remote control and retry.

Verify unit is electrically grounded.
Press max button on PCB to reset; Press min button on PCB to reset.

29 Heat Exchanger Outlet Temp.

Too Low

Clean air inlet screen.
Clean heat exchanger fi ns.

31 Water Inlet Thermistor Fault Check thermistor wiring for damage.

Ohm out thermistor.
Check and clean scale from thermistor.

32 Heat Exchanger Thermistor Fault Check thermistor wiring for damage.

Ohm out thermistor.
Check and clean scale from thermistor.

33 Hot Water Outlet Thermistor Fault Check thermistor wiring for damage.

Ohm out thermistor.
Check and clean scale from thermistor.

34 Ambient Air Thermistor Fault Check thermistor wiring for damage; Ohm out thermistor.

Check and clean ambient air thermistor.
Ensure fan blade is tight on motor shaft and it is in good condition.

Check for restrictions in airfl ow around unit and vent terminal.
35 Improper Thermistor Connection Check that all thermistors are connected to proper connections on PCB.
38 Malfunction of O.D.S. Circuit The sensor itself is not responding to a self check from the PCB. Check

wiring harness. Check for proper voltage.
51 Gas Inlet Solenoid Valve Fault Check gas inlet solenoid valve wiring harness for loose or damage termi-

nals.

Ohm out solenoid valve.
52 Proportional Gas Control Valve

Fault

Check proportional gas control valve wiring harness for loose or damage

terminals.

Ohm out proportional gas control valve.
61 Fan Failure Ensure fan motor will turn freely. (Motor will operate with a small amount

of restriction.)

Check wiring harness to motor for damaged and/or loose connections.

Check venting length not to exceed max lengths and bends.