Paloma PH2-28R OFP, PH2-25R OFN, PH2-20R OFP, PH2-25R OFP, PH2-28R OFN Engineering Handbook

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Tankless Gas Water Heaters

Mid Effi ciency Models
PH2-20R OFN, PH2-25R OFN & PH2-28R OFN (Outdoor Natural Gas Models)
PH2-20R OFP, PH2-25R OFP & PH2-28R OFP (Outdoor L.P. Gas Models)
PH2-20R DVSN, PH2-25R DVSN & PH2-28R DVSN
(Indoor Direct Vent Natural Gas Models)
PH2-20R DVSP, PH2-25R DVSP & PH2-28R DVSP
(Indoor Direct Vent L.P. Gas Models)

High Effi ciency Condensing Models
PHH-25ROFN & PHH-32ROFN (Outdoor Natural Gas Models)
PHH-25ROFP & PHH-32ROFP (Outdoor L.P. Gas Models)
PHH-25RDVN & PHH-32RDVN (Indoor Direct Vent Natural Gas Models)
PHH-25RDVP & PHH-32RDVP (Indoor Direct Vent L.P. Gas Models)

Outdoor Water Heater
PH2-20, 25 & 28ROF

Indoor Direct Vent Water Heate
PH2-20, 25 & 28RDVS

Engineering Handbook

Outdoor Water Heater
PHH-25ROF & PHH-32ROF

I

S

E

D

C

E

R

T

F

I

Indoor Direct Vent Water Heater
PHH-25RDV & PHH-32RDV

G

N

D

E

I

®

CERTIFIED

R

2 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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TABLE OF CONTENTS

General Information

Specifications 4
Sequence of Operations 5

1. Ignition Sequence 6

2. Monitoring Sequence 7

3. Shutdown Sequence 8

Error Code Table 9
Components “Callouts” 15
Maintenance Mode “How To” 16
Control Board “Callouts” 18
Reset Procedure 21
Clearing Fault History 21

Error Code Diagnostics

No Error Code & No Hot Water 22

P1 Warning Code 23
1L Warning Code 24
03 Error Code 25
05 Warning Code 26
10 Warning Code 29
11 Error Code 33

Gas Supply & Venting 33
Igniter Rod (Spark is NOT visible) 34

Flame Rod (Flame IS visible) 36
Gas Control Valve (Spark IS visible; Flame is NOT visible) 38
Control Board 40

12 Error Code 43
Gas Supply & Venting 43
Flame Rod(s) 44
13 Error Code 47
Venting 47

Ground 47
Flame Rod(s) 48

14 Error Code 50
15 Error Code 53
16 Error Code 54
24 Error Code 56
29 Error Code 59
31 Error Code 60
32 Error Code 62

SVC 820-Tankless Gas Trouble Shooting Manual Page | 3

3

TABLE OF CONTENTS

33 Error Code 64
34 Error Code 66
35 Error Code 68
51 Error Code 70
52 Error Code 72
61 Error Code 74
65 Error Code 76
66 Error Code 78
71 Error Code 80
72 Error Code 82
76 Error Code 84
79 Error Code 86
80 Error Code 88
82 Error Code 90
90 Error Code 91
92 Warning Code 92
93 Error Code 92
99 Error Code 93

4 | Page SVC 820 Tankless Gas Trouble Shooting Manual

4

Specifications common to all models

Model See specification sheets for current models and specs

Purpose Domestic Hot Water (DHW) supply for showers, cleaning, and laundry

Rated Gas Input Btu/Hr.) See specification sheets for current models and specs

Dimensions See specification sheets for current models and specs

Installation

Working Water Pressure 14 PSI minimum; 150 PSI maximum

Minimum Water Flow 0.4 GPM to activate burner; can be reduced to .26 GPM once burner is activated

Maximum Water Flow Based on 35 degree rise; See specification sheets for current models and specs

Gas Connection 3/4” NPT Male

Water Connection 3/4" NPT Male

Vent Size Mid Efficiency: 3”/5” Concentric Vent

Max Vent Length See Use & Care Manual for each product type

Inlet Gas Pressure Natural Gas: Minimum 4.0” w.c. Maximum 10.5” w.c.

Hot Water Supply

Temperatures

Electrical

Safety Devices

Freeze Protection Minus 30F (Without Wind-Chill Factor) with power applied

Remote Control

Indoor Wall Mounting : Can be vented horizontally or vertically
Outdoor Wall Mounting : Venting not required

Mid Efficiency : ONLY uses Stainless steel (Category III; 316L Certified)

concentric venting for indoor installation
High Efficiency: Uses PVC; CPVC; ABS; or Stainless Steel (Category III; 316L
Certified) venting for indoor installation

High Efficiency: 2” or 3” Two Pipe Venting (optional concentric vent termination)

L.P. Gas : Minimum 8.0” w.c. Maximum 14.0” w.c.
Factory Setting: 85F – 140F (Up to 140 with Override Adjustment)
Commercial Setting: Up to 185F via program chip
Rating: 120 VAC/60Hz, 3 Amps
Wire : Indoor Models - 3 Prong (Edison) Power Supply Cord

Outdoor Models – require field wiring
Fuse : 3A Fuse x 2 (line voltage)
Flame Rods
Overheat Film Wrap for Heat Exchanger
Heat Exchanger Thermistor (Boiling Point Safety)
Electronic Burner and Combustion Monitoring and Control

Standard: Main Remote Control UMC-117 (included)
Optional: Bath Remote Control USC1-117 – 120 F Max Limit
Optional: Second Bath Remote USC2-117 – 120 F Max Limit

Only one of each type remote above can be installed on a single unit
Only one of each type remote above can be installed on multiple manifold units

SVC 820-Tankless Gas Trouble Shooting Manual Page | 5

5

o

Sequence of Operations

ACTION EXPLANATION

Hot water faucet is open creating a demand Hot water draw initiates water flow thru the water

heater

Water flows thru the Water Flow Sensor Minimum flow rate of .4 GPM to activate @ 35

Control Board senses the flow rate has reached a
minimum demand of .4 GPM@ 35

Blower Motor conducts a pre-purge Pre purge is designed to verify we have a clear and clean

The Proportional Gas Flow Regulator allows the
gas to flow to the main burner

Simultaneously, the Igniter Rod sparks and ignites
the main burner

After ignition, the Flame Rods sense and monitor
the flame and ensure proper combustion

The “In Use Indicator” on the remote control turns
“ON” (Red) and the “Priority Indicator” is Green
(multiple remote controls)

o

T

Control Board is the ‘brains’ of the machine and controls

all input and actions during sequence of operations

vent and supply oxygen to burner for proper ignition

Proportional Gas Flow Regulator initially opens to 75% of

BTU input

The Igniter Rod ignites the fuel in the main burner area.

All burners will fire initially

The purpose of the flame rods is to verify flame and

proper combustion. In the event of flame failure or
improper combustion, the unit will go into an error code

Main burner is now lit. The PCB goes thru a series of

calculations (input sensing) to balance out the cold-water
temperature, the thermostat setting, the hot outlet
temperature, and the BTU required to heat the water.

The Proportional Gas Flow Regulator continuously
adjusts the gas volume in order to maintain the
outlet temperature. The water flow sensor also
adjusts the proper amount of cold water mix flow
to supply a stable hot water temperature at all
times. A signal is also sent to the Blower Motor in
order to constantly maintain the correct
proportion between gas and air volumes

(Indoor Models Only) When the air intake is
blocked, or oxygen is not sufficient, the output of
the Flame Sensor changes

When the hot water tap is closed, the flow rate
signal from the water flow sensor stops

The Fan continues to run for a few minutes Purpose is to cool the heat exchanger, exhaust all

The PCB is constantly monitoring all of these inputs and

actions to ensure the outlet water temperature is within
1-5 degrees of thermostat setting. It also monitors the
BTU required to heat the cold water to the thermostat
setting and adjusts the gas valve accordingly

The PCB senses this change and controls the Fan and Gas

Valve in order to prevent imperfect combustion. If the
PCB cannot correct such condition, the unit will go into
an error code

Gas valve is closed. Main burner shuts off

combustions gases, and to maintain the burner chamber
charged with air for immediate ignition if there is
another hot water demand

T

6

14 – OHL

False

33 – Outlet Thermistor

61

90: > 12 seconds

72: > 5 seconds

11: > 2 Ignition Attempts

Plug In

82 – Program Chip

6 | Page SVC 820 Tankless Gas Trouble Shooting Manual

Health

Check

71 – Gas Control Valve

79 – Blower Motor

76 – Remote Control

1. Ignition Sequence

2. Monitoring Sequence

SEQUENCE OF OPERATIONS:

Open Hot Water Tap

3. Shutdown Sequence

Up &

Down

Buttons

24: Activated > 20 Seconds

Blower On

Thermistors

Check

31 – Inlet Thermistor

32 – HE Thermistor

34 – Ambient Thermistor

Blower

Speed

1 – Ignition Sequence

Flue

Blockage

Flame

Gas Control Valve & Igniter Rod On

Detect

Flame

Igniter Rod Off

YES

1-2

Ignition

Attempt

NO

Next Page

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7

Ignition Failure

10 Warning Code Flashing

05 Warning Code Flashing

11

12

1-2 Ignition

too high

35

52

61

65

66

71

76

79

13

Imperfect

Combustion

Flow Chart

Alarm

No

Decrease of

Fan Motor

Ventilation

No

2 – Monitoring Sequence: while unit is in

operation

Yes Yes

Attempt to Re-Ignite

Yes

Flame Failure

Condensation Not Draining

OHL Activated

Hot Water > 207 Degrees F

for more than 15 seconds

Heat Exchanger > 207

Degrees F for more than 15

seconds

Outlet water temperature

29: Condensing Only

14

15

15

16

Attempts

No

Next Page

Gas Control Valve

Trouble with

Thermistor(s)

PGFR – Gas Control

29 34 33 32 31

Heat Exchanger

Outlet Temp Too

Low

Ambient

Thermistor

Valve

Communication

Trouble – Remote

Control

Blower Motor Water Control Body Bypass Assembly

Outlet Thermistor

Blower Motor

Current Not

Detected

Heat Exchanger

Thermistor

Flame Rod

Inlet Thermistor

8 | Page SVC 820 Tankless Gas Trouble Shooting Manual

8

80: Gas Control Valve

51: Gas Control Valve

99

Close Hot Water Tap

3 – Shutdown Sequence

Gas Control Valve Off

Detect
Flame?

Checking

Blower

Motor

Unit in Stand-By mode

Yes (8 Seconds Later)

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9

Code

P1

Error Code

Fault Remedy

Flow Rate/Maintenance:

Nothing Happens When

No

Water Is Flowing Through

Code

Unit. (Control Board
Displays Water Temp)

Maintenance Warning:

Water Flow Too Low

(Unit Will Still Be
Operable; Minimum Flow

0.40 GPM To Activate @

o

) T

35

Maintenance:

Water Heater Has

1L

Buildup Of Lime/Scale
Deposits

1. Increase water flow rate or set higher temperature

2. New Installations: Ensure hot and cold water lines are not crossed

3. Check for plumbing crossover in the home

4. Clean water inlet filter

5. Check water flow sensor (may be jammed)

1. Check hot water tap flow (clean aerator if necessary)

2. Clean water inlet filter

3. Increase flow rate or set higher temperature

If maintenance requirements are met:

1. Check water flow sensor

1. Flush Heat Exchanger

2. High Altitude Installations: ensure proper altitude settings have been made

03 MIC 185, MIC 6, & EZ Link

Maintenance Warning:

Air Intake Or Vent
Exhaust May Be Blocked
(Unit Will Still Be
Operable)

05

Installation Warning:

The vent Pipes On The
Vent Termination May
Not Be Connected (Unit
Will Still Be Operable)

1. Check communications cable connection

2. Check # 4 dip switch setting is in the ‘ON’ position (Dip Set # 1 (Top), Dip

switch # 4 on the water heaters only)

1. Remove any vent blockage

2. Make sure venting meets all installation requirements

If maintenance requirements are met:

1. Check fan motor

Make sure all venting is properly sealed and meets all venting requirements (diameter;
vent lengths; venting material; venting obstructions; and all other installation
requirements as described in installation manual)

If installation requirements are met:

1. Check Blower Motor

10 | Page SVC 820 Tankless Gas Trouble Shooting Manual

10

Maintenance:

10

Decrease Of Ventilation
Amount (Blower Motor)

Installation/Gas supply:

11

Ignition Failure

Gas supply/Installation/
Maintenance:

12

Flame Failure (Had Main
Burner, Then Lost It)

Clean any blockage in venting, Blower Motor, air intake

If maintenance requirements are met:

1. Check Blower Motor

1. Ensure you have gas to the appliance and valves are turned ‘ON’

2. Ensure gas type, gas pressure, and gas volume are correct

3. Bleed all air from gas lines

4. Ensure gas line, meter, and regulator are sized properly

5. Ensure appliance is properly grounded

If installation/gas supply requirements are met:

1. Check Gas Control valve for open or short circuits

2. Ensure Igniter Rod is operational

3. Check igniter/Flame Rod(s) and Igniter/Flame Rod(s) wiring harness for

damage

4. Check Control Board

5. Check Flame Rod Status

1. Ensure gas type and pressure is correct

2. Bleed all air from gas lines

3. Ensure Flame Rod wire(s) is connected

4. Check Flame Rod(s) for carbon build-up

5. Ensure gas line, meter, and regulator are sized properly

6. Ensure appliance is properly grounded

7. Check power supply for proper voltage and voltage drops

8. Disconnect and re-connect all wiring harnesses on Gas Control Valve and

Control Board

If gas supply/installation/maintenance requirements are met:

1. Check gas valves for open or short circuits

2. Check flame rod(s) and flame rod(s) wiring harness for damage

3. Check PCB

4. Check flame rod(s) status

SVC 820-Tankless Gas Trouble Shooting Manual Page | 11

11

Ensure intake and exhaust venting meet all installation requirements (diameter; vent
lengths; venting material; venting obstructions; and all other requirements as

Indoor ONLY

Venting:

13

Flame Rod FL-2: Reads
Poor Or Improper
Combustion

described in the Use & Care manual {Make sure exhaust is not recirculating into fresh
air intake})

If venting requirements are met:

1. Remove any blockage from venting or from in front of vent termination

2. Verify altitude settings

3. Check Flame Rod FL-2

4. Check Blower Motor

Condensing only:

Maintenance:

Flue Temperature Too
High

14

Mid Efficiency &

Condensing:

Over Heat Limiter (OHL)
Fault

Maintenance:

Boiling Safety Device
(Heat Exchanger

15

temperature reached
207 F degrees for more
than 15 seconds)

Condensing Only:

1. Clean blockage in heat exchanger

2. Remove any blockage from Blower Motor and exhaust vent

Mid Efficiency & Condensing:

If ‘Condensing’ maintenance requirements are met:

1. Verify “U” connector is connected to Control Board

2. Verify wiring harness is connected to OHL

3. Check heat exchanger for cracks and/or separations

4. Inspect Overheat Wrap (Overheat wrap failure: Replace unit)

5. Check thermal overload sensor (condensing models only)

1. Flush Heat Exchanger (lime/scale buildup)

2. Check for closed water heater inlet valve or restrictions in cold water inlet

pipe (must be fully open)

3. On commercial water heater, lower set point temperature below 180

high altitudes

If maintenance requirements are met:

1. Check Heat Exchanger Thermistor

0

F at

Maintenance:

Outlet Water

16

Temperature Is Above
Remote Thermostat
Setting

If maintenance requirements are met:

1. Check for clogged Heat Exchanger

2. Check for restrictions in airflow around unit and vent terminal

1. Check Outlet Thermistor

2. Check Heat Exchanger Thermistor

3. Check gas valve

12 | Page SVC 820 Tankless Gas Trouble Shooting Manual

12

Malfunction Of

24

Operational Switch

Condensing Only:

Maintenance:

Neutralizer Is clogged

29

Mid Efficiency &

Condensing:

Maintenance:

1. Turn off water. Disconnect Remote Control and retry

2. Verify unit is electrically grounded

3. Press MIN and MAX button on Control Board to reset

Condensing Only:

1. Ensure shipping cap for drain line is removed and drain line is not blocked

2. Clear all neutralizer drainage ports inside of unit

3. Clear neutralizer drainage line outside of unit

4. Clean air inlet screen

5. Clean heat exchanger fins

If maintenance requirements are met:

1. Check neutralizer water level electrode

Mid Efficiency & Condensing:

1. Clean air inlet screen

2. Clean heat exchanger fins

Heat Exchanger
Temperature Is Too Low

31 Inlet Thermistor

Heat Exchanger

32

Thermistor

Outgoing Water

33

Temperature Sensor

1. Check Thermistor wiring for damage

2. Check and clean scale from Thermistor

3. Ohm Thermistor

1. Check Thermistor wiring for damage

2. Check and clean scale from Thermistor

3. Ohm Thermistor

1. Check Thermistor wiring for damage

2. Check and clean scale from Thermistor

3. Ohm Thermistor

SVC 820-Tankless Gas Trouble Shooting Manual Page | 13

13

1. Check Thermistor wiring for damage

2. Check and clean Ambient Thermistor

3. Ohm Thermistor

34 Ambient Thermistor

Improper Thermistor

35

Connection

51 Gas Control Valve

PGFR Valve

52

(Modulating Valve)

Installation/Maintenance:

61

Blower Motor

If wiring and component readings are normal:

1. Check for restrictions in airflow around unit and vent terminal

2. Ensure fan blade is tight on motor shaft and spins freely

1. Check that all Thermistors are secured to proper connections on Control

Board

2. Check that all quick connectors between Control Board and Thermistors

1. Check Gas Control Valve wiring harness for loose or damaged terminals

2. Ohm Gas Control Valve

1. Check PGFR Valve wiring harness for loose or damaged connections

2. Ohm PGFR Valve

1. Ensure Blower Motor will turn freely. Motor will operate with a small amount
of restriction

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

3. Check venting length not to exceed max lengths and bends

65 Water Control Valve

66 Water Bypass Valve

71 Gas Control Valve

Flame Rod

72

(Detected False Flame)

1. Check Water Control Valve wiring harness for loose or damaged terminals

2. Check for proper voltage to Water Control Valve

1. Check Water Bypass Valve wiring harness for loose or damaged terminals

2. Check for proper voltage to water by-pass solenoid

1. Check Gas Control Valve wiring harness for loose or damaged terminals

2. Ohm Gas Control Valve

1. Ensure Flame Rod(s) is touching flame when unit fires

2. Check inside burner chamber for any foreign material blocking flame at Flame

Rod(s)

3. Check all wiring to Flame Rod for damage

4. Check Flame Rod for proper voltage

5. Remove Flame Rod and check, clean with steel wool

(Do not use sandpaper)

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1. Check Remote Control wiring for loose or damaged connections

2. Bypass Remote Control: connect Remote Control directly to remote

Communication Fault

76

With Remote Control

connection at bottom of the heater. Replace cable if found to be faulty

3. Remove water heater power cord from 3 prong outlet.

Remote Control. Plug heater back into supply and test heater without Remote
Control connected

Disconnect the

Blower Motor

79

Current Fault

80

&

Gas Control Valve

81

Installation:

82

Control Board Is Not
Programmed.

Maintenance/Installation:

90

Blocked Flue/Air Intake

Condensing Only:

Maintenance Warning:

92

Neutralizer Needs To Be
Replaced (Unit Will Still
Be Operable)

1. Ensure Blower Motor will turn freely. Motor will operate with a small amount

of restriction

2. Check Fan Motor for proper voltage and for water (condensation) damage

1. Ohm Gas Control Valve

2. Check voltage of all Flame Rods

Verify Program Chip is installed

Clean any blockage in Heat Exchanger, Blower Motor, inlet flue and exhaust flue

Replace Neutralizer

Condensing Only:

Maintenance:

93

Neutralizer Must Be
Replaced (Unit Will NOT
Operate)

Maintenance/Installation:

99

Blower Motor Cannot
Vent

Replace Neutralizer

1. Clear vent blockages

2. Check for blocked Heat Exchanger

SVC 820-Tankless Gas Trouble Shooting Manual Page | 15

15

COMPONENTS

1. Condensing ONLY: Secondary
Stainless Steel Heat Exchanger

2. Condensing ONLY: Neutralizer

3. Primary Heat Exchanger

4. Flame Rod(s)

1

5. Sight Glass

6. Igniter Rod

7. Igniter Coil

8. Gas Control Valve

9. Water Control Valve

10. Water Bypass Valve

11. Control Board

12. Blower Motor (Behind Control Board)

A. Heat Exchanger Thermistor
B. Outlet Thermistor
C. Inlet Thermistor
D. Ambient Thermistor

2

A

B

4

11

3

5

10

9

C

6

7

D

8

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16

Maintenance Mode Panel Di spl ay

The Rheem Tankless has a Maintenance Mode chart on the Remote Control.
To access the Maintenance Mode, turn the unit OFF at Remote Control. Then
hold down the UP and DOWN arrow keys at the same time for 5 seconds.
You will hear an audible beep and see the display go to 1E. By pressing the
UP and DOWN arrow keys on the remote thermostat, you can access a
variety of information about the water heater. To activate the unit while
displaying the maintenance panel: push the power button once, open a hot
water fixture, and the green LED will illuminate. This will allow you to access
a variety of real time information while the unit is in operation.

Shortcut: Lift dip switch #1 to the up position to go immediately into maintenance mode. This can be
done while the water heater is in operation.

While in Maintenance Mode you want to push the up arrow key to select the table you wish to view.
The table is designated by a letter and is always displayed as the second digit. Then push the down
arrow key to display the number item in the table you selected. You can select as many as 8 readings
for each table.

To perform diagnostics in this service manual, press the up arrow until you get to table

Now using your down arrow you can change the number in front of
diagnostic readings, the selected table will flash first and then the diagnostic reading. You will see the

following as you navigate the

0Y = Flame Rod Status

1Y = Water Flow in gallons per minute

2Y = Ambient air temperature

3Y = Water inlet temperature

4Y = Heat exchanger temperature

5Y = Hot water outlet temperature

6Y = Fan speed (x 100 rpm)

7Y = Power for modulating gas valve

8Y = Null (no reading)

Y table:

Y. As you move through the

1Y.

9Y = Null (no reading)

*FULL MAINTENANCE DISPLAY CHART AVAILABLE ON NEXT PAGE*

SVC 820-Tankless Gas Trouble Shooting Manual Page | 17

17

Fault Codes of the most recent 8 f aults

Flame Rod
GPM Flow Rate

Hot Water

Fan Speed x 100

Power for

MAINTENANCE INFORMATION TABLE

First Digit – Use DOWN arrow key on Remote Control

0* 1* 2* 3* 4* 5* 6* 7* 8* 9*

*E Null

*F Null Sequence Number of the most recent 8 faults Null

*C Total combustion times until recent error fault (** x 10000times) Null

*D Total combustion times until recent error fault (** x 100 times) Null

*H Total combustion period until recent error fault (** x 1000 hours) Null

*J Total combustion period until recent error fault (** x 10 hours) Null

*Y

Status

*A

Second Digit – Use UP arrow key on Remote Control

Null

Control

(*.* GPM)

Line Fan

Ambient Air

Temperature

Detective

Value

Cold Water Inlet

Temperature

Fan Motor

Current

Heat Exchanger

Temperature

Null

Outlet

Temperature

Null

RPM

P.G.F.R. valve

Null

Null

Null

Null

Null

Null

Sequence

Number

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18

CONTROL BOARD – Color Picture

• Each letter indicates the connector identifier

M T

ADJ

SVC 820-Tankless Gas Trouble Shooting Manual Page | 19

19

CONTROL BOARD

DIP #1 – Adjust max temperature; EZ Link cable

DIP #2 – Adjust for altitude differential

MIN & MAX (SW1 & SW2) – Adjust water

temperature setting; gas pressure; etc.

ADJ (SW3) – Adjust gas pressure etc.

M – Flame Rod for all models (detects flame)

T – Flame Rod for indoor models only (monitors

combustion efficiency)

F – Communication port (manifold installations)

A – Fuel type and temperature Program Chip

U – Over Heat Limiter (OHL)

R – Thermistors (Ambient, Inlet, Outlet, Heat

Exchanger) & Modulating Gas Valve (PFGR)

S – Water Flow Sensor

C – Water Control Valve

B – Water Bypass Valve

V – Remote Control (Main Bath)

G – Blower Motor

K – Gas Control Valve

H – Igniter Rod

20 | Page SVC 820 Tankless Gas Trouble Shooting Manual

20

NOTES:
______________________________________________

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______________________________________________
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______________________________________________
______________________________________________
______________________________________________
______________________________________________
______________________________________________
______________________________________________

SVC 820-Tankless Gas Trouble Shooting Manual Page | 21

21

RESET PROCEDURE:

1. Turn unit OFF. Remove Front Cover. Locate the Dip Switches on

the Control Board.

2. Make sure all the Dip Switches are OFF (down position).

3. Locate the #2 Dip Switch and turn it ON (up position) then

immediately turn it off.

4. Within 5 seconds, press and hold the MIN and MAX button for at

least 2 seconds.

5. The Remote Control will flash briefly.

6. You can operate unit.

CLEARING FAULT HISTORY PROCEDURE:

1. Turn unit OFF. Remove Front Cover. Locate the Dip Switches on

the Control Board.

2. Make sure all the Dip Switches are OFF (down position).

3. Locate the #1 Dip Switch and turn it ON (up position) then

immediately turn it off.

4. Within 5 seconds, press and hold the MIN and MAX button for at

least 2 seconds.

5. The Remote Control will flash briefly. This indicated the fault

history has been cleared.

6. You can verify clearing history by entering Maintenance Mode

and check the code at location 1E. Should read NULL.

22 | Page SVC 820 Tankless Gas Trouble Shooting Manual

22

No Error Code & No Hot Water

(Remote Control Displays Hot Water Temperature Setting)

Explanation: No hot water is delivered when water is flowing through unit and Remote Control displays the hot water
temperature setting.

Possible Causes:

• Water Flow

• DIP 1 Setting On Main Control Board (PCB)

• Water flow sensor

Water Flow:

1. Turn OFF water supply to unit. Turn Remote Control OFF; unplug power cord at wall outlet. Wait 10 seconds; plug

power cord back into outlet; wait 20 seconds; turn the Remote Control ON. Turn water supply ON; check the nearest
hot water fixture for hot water. If you have hot water, then the unit needed to be reset.

2. Water flow might be too low. Open multiple hot water fixtures. If unit fires then there is not enough water flow to

engage the unit at a particular fixture. Check your fixture aerator screen(s) for debris. Clean if necessary.

3. Your water lines might be crossed. Make sure your hot and cold water supply lines are connected to the appropriate

hot and cold water assembly connections on the unit.

4. Your water flow may be restricted by a debris in Water Filter. Remove the water filter and inspect. Clean if

necessary.

Dip 1 Setting:

All Dip 1 switches must be in the ‘OFF’ position.

Manifold Units ONLY: Go to Error Code 03 to verify proper DIP 1 setting

DIP #1

SVC 820-Tankless Gas Trouble Shooting Manual Page | 23

23

P1 - Warning C ode

Explanation: No hot water is delivered when water is flowing through unit and Remote Control displays P1. When water flow
does not reach a minimum 0.4 GPM rate @ 35

Possible Causes:

• Not Enough Water Flow

Water Flow:

Turn the water supply to the unit off. Turn the remote thermostat off, wait 10 seconds and turn the remote thermostat on.
Turn the water supply to the unit on and check the nearest hot water fixture for hot water. If you have hot water, then the unit
needed to be reset.

Your water lines might be crossed. Make sure your hot and cold water supply lines are connected to the appropriate hot and
cold water connections on the unit.

Water flow might be too low. Open multiple hot water fixtures. If unit fires then there is not enough water flow to engage the
unit at a particular fixture. Check your fixture aerator screen(s) for debris. Clean if necessary.

o

T, for five seconds, P1 warning code is displayed.

Your water flow may be restricted by a dirty In-Line Water Filter. Remove the water filter and inspect. Clean if necessary.

24 | Page SVC 820 Tankless Gas Trouble Shooting Manual

24

1L - Warning C ode

Explanation: The Control Board has detected possible lime build-up inside the heat exchanger. To prevent permanent damage
to the unit, the unit must be drained and flushed. Flushing procedures may need to be repeated for excessive lime and scale
build-up. To reset 1L Code, hold down the MIN and MAX buttons at the same time for 10 seconds.

Lime and scale flushing procedure for tankless water heaters:

In areas with hard water conditions the tankless water
heater can develop lime and scale deposits in the heat
exchanger. These depo sits can restrict the water flow and
degrade the performance of your water heater. These
instructions are to provide a safe and effective means to
remove lime and scale build up in the heat exchanger of
your tankless water heater. If you are not co mfortable with
this procedure, then seek the assistance of a plumbing
professional.

Flushing Procedure with Isolation Valves: If your
tankless water heater is not installed with isolation valves,
it is recommended that you seek the assistance of a
plumbing professional.

1. Turn off the electricity and gas, to the tankless

water heater. Do not perform this procedure with
power or gas turned on; damage to the water
heater can occur.

2. Shut off the main water supply valve to the

tankless water heater. Consult the instructions
provided by the isolation valve manufacturer for
specifics in using their valve assemblies.

3. Attach a small garden hose on each drain valve.

Connect the cold water hose to the output of a
small circulation pump. A pond pump or similar
model can be used for this application.

4. Pour approximately five gallons of virgin food

grade white vinegar into a pail.

5. Place the inlet hose of the pump and the drain

hose from the hot water heater into the pail.

6. Open the drain valves and turn on the pump.

Allow solution to circulate for approximately 45
minutes to an hour.

7. Turn off the pump and drain the vinegar from

water heater. Close the cold water drain valve.

8. Open the main cold water supply valve and allow

fresh water to flush through the water heater for
at least 5 minutes to remove all traces of vinegar
from the system.

9. Close the cold water main valve and remove

water filter screen located in cold water inlet of
water heater. Clean the screen of any sediment or
dirt and reinstall the filter. See the Use and Care
Manual provided with your tankless water heater
for detailed instructions.

10. Turn on the water shutoff valves, run a hot water

tap to purge any air from the water lines and
check the system for an y leaks.

11. Turn on gas, electricit y, and remote control

thermostat and set the desired temperature.

12. Run hot water from several locations to check the

operation and performance of the wat er heater.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 25

25

03 - Error Code

(Only for manifold installations utilizing EZ-Link; MIC-6; or MIC-185)

Explanation: Communication failure between water heaters, remote control, and/or manifold controller.

Diagnostic Checks:

• DIP1 Setting On Main Control Board (PCB)

DIP 1 SETTING:

Manifold units only: DIP #1, switch #4 must be in the ‘ON’ position for each unit

Check ALL Molex connections on ALL Control Boards

26 | Page SVC 820 Tankless Gas Trouble Shooting Manual

26

05 – Warning Code

Explanation: The Flame Rod has detected improper burner combustion. The unit is NOT able to maintain the proper fuel/air
mixture for proper combustion. This warning code is commonly caused by VENTING and/or GAS SUPPLY. The unit will
continue to operate and attempt to resolve improper combustion, but may eventually shut down with an error code 11, 12, or

13.

Diagnostic Checks:

• GAS SUPPLY & VENTING

• Dip #2 Setting On Printed Circuit Board (PCB)

Make sure you have sufficient fuel for the unit to operate properly.

1. Gas Type (LP or Natural Gas)

2. Gas Pressure

3. Gas Pipe Size

4. Gas Flex Line Not To Exceed 36” In Length, Has The Proper ID (Inside Diameter), & Correct BTU Rating

5. Gas Regulator

6. Gas Shut Off Valves

7. Air In Gas Line

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

GAS SUPPLY & VENTING

SVC 820-Tankless Gas Trouble Shooting Manual Page | 27

27

op right of PCB.

Switch labeled DIP #2 is the bottom switch.

DIP #2 SETTING:

1

Locate the two DIP switches at t

2

Sea Level to 3,280 Feet

DO NOT ALTER ANY OTHER SWITCHES

3

4

28 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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SVC 820-Tankless Gas Trouble Shooting Manual Page | 29

29

10 – Warning Code

Explanation: The Blower Motor is not creating enough ventilation. The system passed the pre-purge cycle, but detects vent
blockage during normal operation. The unit will continue to operate but may eventually shut down with Error Code 99.

First check your GAS SUPPLY & VENTING; the most common causes for Error Code 10.

Diagnostic Checks:

• GAS SUPPLY & VENTING

• Blower Motor

GAS SUPPLY & VENTING

Make sure you have sufficient fuel for the unit to operate properly.

1. Gas Type (LP or Natural Gas)

2. Gas Pressure

3. Gas Pipe Size

4. Gas Flex Line Not To Exceed 36” In Length, has the proper ID (Inside Diameter), and correct BTU rating

5. Gas Regulator

6. Gas Shut Off Valves

7. Air In Gas Line

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

30 | Page SVC 820 Tankless Gas Trouble Shooting Manual

30

BLOWER MOTOR DIAGNOSTICS:

1

Control Board

2

Screws

Turn power OFF. Remove and reinsert connector “G” on

Control Board. Attempt to operate unit again. IF 10

Warning Code does NOT display, unit had a loose

connection.

3

Blower Motor

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T”, & “G”.

Pull PCB out of way to access Blower Motor.

Bottom of Unit

4

Remove 3 screws holding Blower Motor in place. Clean
Blower Motor and reassemble unit. Attempt to operate

unit again. IF 10 Warning Code does NOT display:

Blower Motor needed to be cleaned.

Locate Min & Max buttons on Control Board.

Continue to diagnostic chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 31

31

Remove and reinsert connector “G” at

Control Board.

Attempt to operate unit again.

18 DC VOLTS

Control Board.

Attempt to operate unit again.

Control Board and Blower Motor are ‘OK’:

BLOWER MOTOR Diagnostic Chart

Test DC voltage across black and red

wires on connector “G”:

144 – 192 DC VOLTS

Press and hold down “MAX” button on Control Board

to activate the Blower Motor. While Blower Motor is
running, test DC voltage across black and white wires

Is the DC voltage

OK?

YES

on connector “G”:

12 –

NO

IF unit continues to display Error Code 10:

Replace Control Board

Attempt to operate unit again. If unit

continues to display Warning Code 10:

CHECK VENTING & GAS SUPPLY

Is the DC voltage

OK?

YES

Press and hold down “MAX” button on Control Board

to activate the blower motor. While blower is

running, test DC voltage across black and blue wires

on connector “G”:

4 – 10 DC VOLTS

Is the DC voltage

YES NO

OK?

NO

Remove and reinsert connector “G” at

IF unit continues to display Error Code 10:

Replace Control Board

Replace Blower Motor

32 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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33

11 – Error Code

Explanation: This error code is commonly a result of GAS SUPPLY and/or VENTING. Flame Rod(s) does not detect flame. This
Is caused by the following: Inadequate GAS SUPPLY; Inadequate VENTING; Igniter Rod NOT sparking; Build-up on Flame Rod(s)
caused by inadequate GAS SUPPLY and/or VENTING; Gas Valve.

IMPORTANT: If all water heater components test ‘OK’, you must thoroughly inspect your GAS SUPPLY & VENTING.

First Check: GAS SUPPLY & VENTING

Diagnostic Checks:

• GAS SUPPLY & VENTING

• Igniter Rod

• Flame Rod(s)

• Gas Control Valve

Make sure you have sufficient fuel for the unit to operate properly.

1. Gas Type (LP or Natural Gas)

2. Gas Pressure

3. Gas Pipe Size

4. Gas Flex Line Not To Exceed 36” In Length, has the proper ID (Inside Diameter), and correct BTU rating

5. Gas Regulator

6. Gas Shut Off Valves

7. Air In Gas Line

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

GAS SUPPLY & VENTING

34 | Page SVC 820 Tankless Gas Trouble Shooting Manual

34

IGNITER ROD DIAGNOSTICS: (spark is NOT visible)

1

Turn power OFF. Remove and reinsert connector “H” on

Control Board.

2

Igniter Coil

Remove and reinsert white Molex connector at Igniter

Coil mounted on right side of unit.

3

Remove and reinsert Igniter Coil cable on Igniter Rod.

Turn power ON.

Igniter Rod

4

Sight Glass

While unit is attempting to ignite, determine IF spark is

visible through sight glass. IF YES, unit had a loose

connection. IF NO, continue to diagnostic chart on next

page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 35

35

Attempt to operate unit again.

across Igniter Coil

IGNITER ROD Diagnostic Chart

Check AC Volts across 2 grey wires on

connector “H” while unit is attempting to

ignite:

108 – 132 Volts AC

Is the voltage

OK?

YES

Remove Igniter Coil cable from Igniter Rod. While

unit is attempting to ignite, hold end of Igniter Coil

cable 1/8” from end of Igniter Rod.

Make sure you hold Igniter Coil cable on the rubber

insulation while performing this check

NO

IF Igniter Rod does not spark and unit

malfunctions due to Error Code 11:

Replace Control Board

Igniter Rod is ‘OK’

IF unit fails again due to Error Code 11:

IF flame IS visible, diagnose Flame Rods

IF flame is NOT visible, diagnose

Gas Control Valve

Does spark arc

NO

cable and Igniter

Rod?

YES

Remove Igniter Rod and clean.

Reconnect Igniter Coil cable and Igniter Rod.

Attempt to operate unit again.

Is spark visible

YES

through sight

glass?

NO

Replace Igniter Coil

Replace Igniter Rod

36 | Page SVC 820 Tankless Gas Trouble Shooting Manual

36

remove any foreign debris. IF foreign debris NOT present:

Remove and reinsert terminals on Flame Rods(s)*.

le.

For Maintenance Mode instructions go to page 16.

FLAME ROD(S) DIAGNOSTICS: (flame IS visible)

1

Turn power OFF. Remove and reinsert white connector

“M” and blue connector “T” on Control Board.

2

Flame Rod(s)*

Attempt to operate unit again. IF 11 Error Code does NOT

display, unit had a loose connection.

*Indoor Models ONLY:

2 Flame Rods

3

Sight Glass

Locate sight glass. While unit is attempting to ignite,

determine if flame is touching Flame Rod(s). IF NO,

CHECK GAS SUPPLY & VENTING.

On Remote Control; go to Maintenance Mode 0Y tab

Continue to diagnostic chart on next page.

4

SVC 820-Tankless Gas Trouble Shooting Manual Page | 37

37

detecting flame?

Indoor Models: 05

Remove and clean Flame Rod(s).

Attempt to operate unit again.

FLAME ROD(s) Diagnostic Chart

Cycle unit ON and check AC Volts at

white “M” & blue “T” connectors:

1 – 100 AC VOLTS

Flame Rod status under table 0Y. IF detecting flame,

Is the AC voltage

OK?

YES

Cycle unit ON; while in Maintenance Mode check

Maintenance Mode will display:

Outdoor Models: 01

Is Flame Rod(s)

NO

NO

Attempt to operate unit again.

IF unit malfunctions due to Error Code 11:

Replace Control Board

IF Flame Rod(s) still does not detect flame:

Replace Flame Rod(s).

Attempt to operate unit again. If the unit

*CHECK: GAS, VENTING, & GROUND*

YES

malfunctions due to an Error Code 11:

Flame Rod(s) are ‘OK’

38 | Page SVC 820 Tankless Gas Trouble Shooting Manual

38

connector with black wire on PGFR.

Molex Connectors

GAS CONTROL VALVE DIAGNOSTICS: (Igniter Rod DOES spark & NO flame)

1

Turn power OFF. Remove and reinsert connector “K” on

Control Board.

2

Remove and reinsert connector “R” on Control Board.

3

Locate PGFR valve on lower right of unit. Remove and

reinsert Molex connector with red wire and Molex

Attempt to operate unit again.

4

PGFR

IF 11 Error Code does NOT display, unit had a loose

IF 11 Error Code IS displayed, continue to diagnostic chart

connection.

on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 39

39

Is the DC voltage

Attempt to operate unit again.

Remove and reconnect terminals on PGFR.

Attempt to operate unit again.

GAS CONTROL VALVE Diagnostic Chart

While unit is attempting to ignite, check
DC voltage across red wire #1 and black

wire #2 on connector “R”:

OK?

NO

IF the unit malfunctions due to an Error

Code 11:

1.5 – 14 DC VOLTS

YES

Turn unit OFF; remove Molex connector “R”.

Measure resistance across red wire #1 and black wire

#2 on Molex connector “R”:

40 – 80 Ohms

Is the resistance

OK?

NO

Replace Control Board

IF unit malfunctions due to Error Code 11:

Replace Gas Control Valve

Continue to next page

YES

PGFR is ‘OK’

40 | Page SVC 820 Tankless Gas Trouble Shooting Manual

40

Measure resistance across black wire #6

ire #6

Measure resistance across black wire #6

ure resistance across black wire #6

Turn unit OFF and remove Molex connector

GAS CONTROL VALVE Diagnostic Chart

Measure resistance across black wire #6

and yellow wire #1 on Molex connector

and white wire #2 on connector “K”:

Meas

and grey wire #3 on connector “K”:

“K”:

0.8k – 2.4k Ohms

0.8k – 2.4k Ohms

0.8k – 2.4k Ohms

“K” to measure resistance

Is the

resistance

OK?

YES

Is the

resistance

OK?

YES

Is the

resistance

OK?

NO

NO

NO

Replace Gas Control Valve

Replace Gas Control Valve

Replace Gas Control Valve

and red wire #5 on connector “K”:

0.8k – 2.4k Ohms

Measure resistance across black w

and blue wire #4 on connector “K”:

0.8k – 2.4k Ohms

Gas Control Valve is ‘OK’

Continue to next page

YES

Is the

resistance

OK?

YES

Is the

resistance

OK?

YES

NO

Replace Gas Control Valve

NO

Replace Gas Control Valve

SVC 820-Tankless Gas Trouble Shooting Manual Page | 41

41

90 – 120 DC Volts

Measure DC voltage across black wire #6

Measure DC voltage across black wire #6

Measure DC voltage across black wire #6

Measure DC voltage across black wire #6

Control Board is ‘OK’

CONTROL BOARD Diagnostic Chart

All voltage checks must be performed while unit is attempting to go to main burner and Molex connector “K” IS

Measure DC voltage across black wire #6

and yellow wire #1 on connector “K”:

and white wire #2 on connector “K”:

90 – 120 DC Volts

and grey wire #3 on connector “K”:

connected to Control Board. Restart unit after each voltage check.

Is the voltage

OK?

YES

Is the voltage

OK?

YES

Is the voltage

OK?

NO

Replace Control Board

NO

Replace Control Board

NO

Replace Control Board

90 – 120 DC Volts

and red wire #5 on connector “K”:

90 – 120 DC Volts

and blue wire #4 on connector “K”:

90 – 120 DC Volts

YES

Is the voltage

OK?

YES

Is the voltage

OK?

YES

NO

Replace Control Board

NO

Replace PCB

IF all components tested ‘OK’:

**CHECK GAS, VENTING, & GROUND**

42 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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43

12 – Error Code

Explanation: Commonly a result of inadequate GAS
SUPPLY. Unit detected the presence of flame then Flame
Rod lost flame recognition.

Diagnostic Checks:

First Check: *GAS SUPPLY & VENTING*

GAS SUPPLY & VENTING

**REFER TO USE & CARE MANUAL**

Make sure you have sufficient fuel for the unit to operate properly.

1. Gas Type (LP or Natural Gas)

2. Gas Pressure

3. Gas Pipe Size

4. Gas Flex Line Not To Exceed 36” In Length, has the proper ID (Inside Diameter), and correct BTU rating

5. Gas Regulator

6. Gas Shut Off Valves

7. Air In Gas Line

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

• GAS SUPPLY & VENTING

• Flame Rod(s)

• Gas Control Valve

44 | Page SVC 820 Tankless Gas Trouble Shooting Manual

44

remove any foreign debris. IF foreign debris NOT present:

Remove and reinsert terminals on Flame Rod(s)*.

On Remote Control; go to Maintenance Mode 0Y table.

For Maintenance Mode instructions go to page 16.

*Indoor Models ONLY:

FLAME ROD(S) DIAGNOSTICS: (flame IS visible)

1

Turn power OFF. Remove and reinsert white connector

“M” and blue connector “T” on Control Board.

2

Flame Rod(s)*

Attempt to operate unit again. IF 11 Error Code does NOT

display, unit had a loose connection.

2 Flame Rods

3

Sight Glass

Locate sight glass. While unit is attempting to ignite,

determine if flame is touching Flame Rod(s). IF NO,

CHECK GAS SUPPLY & VENTING.

Continue to diagnostic chart on next page.

4

SVC 820-Tankless Gas Trouble Shooting Manual Page | 45

45

detecting flame?

Indoor Models: 05

Attempt to operate unit again.

FLAME ROD(s) Diagnostic Chart

Cycle unit ON and check AC Volts at

white “M” & blue “T” connectors:

1 – 100 AC VOLTS

Is the AC voltage

OK?

YES

Cycle unit ON; while in Maintenance Mode check

Flame Rod(s) status under table 0Y. IF detecting

flame, Maintenance Mode will display:

Outdoor Models: 01

Is Flame Rod(s)

NO

NO

Attempt to operate unit again.

IF the unit malfunctions due to an Error

Code 12:

Replace Control Board

Remove and clean Flame Rod(s).

IF Flame Rod(s) still does not detect flame:

Replace Flame Rod(s).

*CHECK: GAS, VENTING, & GROUND*

YES

Attempt to operate unit again. IF the unit

malfunctions due to an Error Code 12:

Flame Rods(s) are ‘OK’

46 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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SVC 820-Tankless Gas Trouble Shooting Manual Page | 47

47

connections on lower left side of PCB.

13 – Error Code

Explanation: Indoor units ONLY. Flame Rod 2 (FL #2) is detecting poor combustion. This is commonly caused by inadequate or
improperly installed VENTING (venting includes fresh air intake and exhaust). Other possible causes: Poor or NO ground
connection; dirty or defective FL #2.

*If unit shuts down 5 times within a 4 hour period due to an error code 13, the unit must be reset by performing reset
procedure on page 21.

First Check: VENTING (Primary cause is blockage of the Fresh Air Intake Vent)

Diagnostic Checks:

• VENTING

• Ground Connection

• Flame Rod FL-2

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

VENTING:

GROUND CONNECTION DIAGNOSTICS:

1

Locate and visually inspect green ground wire

Ensure the wires are connected properly and not

damaged.

Ensure you have a proper ground at power supply to

unit.

2

48 | Page SVC 820 Tankless Gas Trouble Shooting Manual

48

remove any foreign debris. IF foreign debris NOT present:

ame Rod(s)*.

On Remote Control; go to Maintenance Mode 0Y table.

For Maintenance Mode instructions go to page 16.

FLAME ROD(S) DIAGNOSTICS: (flame IS visible)

1

Turn power OFF. Remove and reinsert white connector

“M” and blue connector “T” on Control Board.

2

Flame Rod(s)*

Remove and reinsert terminals on Fl

Attempt to operate unit again. IF 11 Error Code does NOT

display, unit had a loose connection.

*Indoor Models ONLY:

2 Flame Rods

3

Sight Glass

Locate sight glass. While unit is attempting to ignite,

determine if flame is touching Flame Rod(s). IF NO,

CHECK GAS SUPPLY & VENTING.

Continue to diagnostic chart on next page.

4

SVC 820-Tankless Gas Trouble Shooting Manual Page | 49

49

detecting flame?

Indoor Models: 05

Remove and clean Flame Rod(s).

Attempt to operate unit again.

FLAME ROD(s) Diagnostic Chart

Cycle unit ON and check AC Volts at

white “M” & blue “T” connectors:

1 – 100 AC VOLTS

Is the AC voltage

OK?

YES

Cycle unit ON; while in Maintenance Mode check

Flame Rod(s) status under table 0Y. IF detecting

flame, Maintenance Mode will display:

Outdoor Models: 01

Is Flame Rod(s)

NO

NO

Attempt to operate unit again.

IF the unit malfunctions due to an Error

Code 13:

Replace Control Board

IF Flame Rod(s) still does not detect flame:

Replace Flame Rod(s).

Flame Rod(s) are ‘OK’ – Unit operation is normal:

YES

Attempt to operate unit again. If the unit

malfunctions due to an Error Code 13:

CHECK VENTING

50 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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Mid Efficiency ONLY:

High Efficiency ONLY:

a loose connection.

OHL

Over Temp Switch

14 – Error Code

Explanation:
Mid & High Efficiency: Over Heat Limiter (OHL)

malfunction.

High Efficiency ONLY:

Over heat condition in the venting has triggered the Over
Temp Limit Switch

OHL DIAGNOSTICS:

1

Diagnostic Checks:

• Mid & High Efficiency:

OHL

• High Efficiency ONLY:

Over Temp Limit Switch

2

Turn power OFF. Remove and reinsert white

connector “U” on Control Board (white Molex with 2

white wires). Attempt to operate unit again.

IF 14 Error Code does NOT display, unit had a loose

connection. IF 14 Error Code IS displayed, continue to

diagnostic chart on next page.

3

IF 14 Error Code does NOT display, unit had

IF 14 Error Code IS displayed, locate the over

temp switch and continue to diagnostic

chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 51

51

inadequate VENTING.

14 – Error Code Diagnostic Chart

Turn power OFF and remove Molex

connector “U”. Measure resistance

between both white wires:

Mid Efficiency Unit ONLY:

Replace Unit

Reconnect the Molex; attempt to operate unit again.

50K – 500K Ohms

Is the resistance

to the OHL ‘OK’?

YES

Did the unit shut

down due to

Error Code 14?

NO

NO

The OHL has activated due to excessive

temperatures. This is normally caused by

inadequate/wrong GAS SUPPLY or

Check GAS SUPPLY & VENTING

Unit had a loose connection, operation

appears to be normal.

NO

Is this a High

Efficiency Unit?

YES

High Efficiency ONLY:

Check for continuity across the

Over Temp Switch

Is the continuity

‘OK’?

YES

Replace Control Board

High Efficiency ONLY:

NO

Replace Over Temp Switch

YES

High Efficiency ONLY:

Replace Unit

52 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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______________________________________________
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______________________________________________
______________________________________________
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SVC 820-Tankless Gas Trouble Shooting Manual Page | 53

53

15 – Error Code

Explanation: The hot water temperature and/or heat exchanger temperature reached 207 degrees F for more than 15
seconds.
IMPORTANT: Inadequate GAS SUPPLY and/or VENTING will create hot spots in the heat exchanger.

Diagnostic Checks:

• GAS SUPPLY & VENTING

• Sediment Build-Up in Heat Exchanger

• Heat Exchanger Temperature Sensor

Make sure you have sufficient fuel for the unit to operate properly.

1. Gas Type (LP or Natural Gas)

2. Gas Pressure

3. Gas Pipe Size

4. Gas Flex Line Not To Exceed 36” In Length, has the proper ID (Inside Diameter), and correct BTU rating

5. Gas Regulator

6. Gas Shut Off Valves

7. Air In Gas Line

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

SEDIMENT BUILD-UP DIAGNOSTICS:

Go to Error Code 1L for flushing instructions

HEAT EXCHANGER TEMPERATURE SENSOR DIAGNOSTICS:

Go to Error Code 32 for Heat Exchanger Temperature Sensor diagnostic instructions.

GAS SUPPLY & VENTING

54 | Page SVC 820 Tankless Gas Trouble Shooting Manual

54

16 – Error Code

Explanation: Outlet water temperature is too hot. The
water temperature is above the set point on Remote
Control.
Check the Outlet Thermistor FIRST.

Diagnostic Checks:

1. Outlet Thermistor

2. Water Bypass Valve

OUTLET WATER TEMPERATURE SENSOR DIAGNOSTICS:

1 2

Control Board

Turn power OFF. Remove connector “R” on Control
Board. Measure resistance between Black #3 & red

#4 wires: 7K – 23K Ohms. IF OK, attempt to operate

unit again. IF 16 Error Code does NOT display, unit

IF resistance tested OK and 16 Error Code IS

displayed, go to Error Code 66 for Water Bypass Valve

diagnostics. IF resistance NOT OK, go to step 2.

had a loose connection.

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &
“G”. Pull control board out of way to access BLACK

Molex for Outlet Thermistor located near the Blower

Bottom of Unit

Motor.

Screws

Molex Connectors

3

Separate top and bottom of BLACK

Molex for Outlet Thermistor. Top of

Molex has 2 black wires and 1 red

wire. Bottom of Molex has 2 black

wires. Continue to diagnostic chart

on next page.

Outlet Thermistor

SVC 820-Tankless Gas Trouble Shooting Manual Page | 55

55

Clean Outlet Thermistor. Retest

16 – Error Code Diagnostic Chart

Check the resistance across 2 black wires

on bottom Molex:

7k – 23K Ohms

connector “R” and black wires on black Molex located

Is the resistance

to the Outlet

Thermistor OK?

YES

Remove Molex from connector “R” at Control Board.

Check continuity from black #3 wire at Molex

behind Control Board. Check continuity from red #4

wire at Molex connector “R” and red wire on black

Molex located behind Control Board

Is the continuity

across all wires

OK?

NO

NO

Thermistor. IF tests OK, the water heater

appears to be normal, attempt to operate

unit again. IF resistance NOT OK:

Replace Outlet Thermistor

Replace wiring harness for connector “R”

on Control Board

YES

Attempt to operate unit again.

If the unit malfunctions due to an Error Code 16:

Go to Error Code 66 for Water Bypass Valve

diagnostics

56 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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1

loose connection.

24 – Error Code

Explanation: Remote Control buttons were depressed for more than 20 seconds. IF you were manually holding down any
Remote Control buttons for more than 20 seconds, release the buttons and NO Error Code will be displayed. Unit will operate
normally. IF error code 24 is still displayed after releasing Remote Control buttons, continue to Remote Control diagnostics.

Diagnostic Checks:

• Remote Control

REMOTE CONTROL DIAGNOSTICS:

Visually inspect Remote Control wiring for damaged or

loose terminals.

Remote Control

2

Wiring Terminals

Hot Water Outlet

Cold Water Inlet

Turn power OFF. Remove and reconnect Remote Control

wiring terminals at bottom of unit. Attempt to operate

unit again. IF 24 Error Code does NOT display, unit had a

IF 24 Error Code IS displayed, continue to diagnostic chart

on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 57

57

24 – Error Code Diagnostic Chart

Unplug unit and remove Remote Control

wires from wiring terminals on bottom of

unit. Use a new short piece of wire to

connect the Remote Control directly to

the Remote Control Wiring Terminals

located at bottom of unit. Plug unit in

and open a hot water source.

Did the unit

display Error

Code 24?

YES

Replace Remote Control

NO

The wiring is defective.

Replace Remote Control wiring.

58 | Page SVC 820 Tankless Gas Trouble Shooting Manual

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NOTES:
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SVC 820-Tankless Gas Trouble Shooting Manual Page | 59

59

29 – Error Code

Explanation:
High Efficiency Condensing Units ONLY:
Condensate Drain is NOT draining.

CONDENSATE DRAIN DIAGNOSTICS:

1

Diagnostic Checks:

• Plug not removed from condensate drain

• Pinch in condensate drain line

• Blockage in condensate drain line

• Drain line has unnecessary “P” trap

2

Drain Line

Ensure you removed the condensate protection plug

located at bottom of unit.

Check your condensate drain line for internal or external

blockage. Make sure drain line is NOT pinched.

60 | Page SVC 820 Tankless Gas Trouble Shooting Manual

60

Motor.

31 – Error Code

Explanation:
Inlet Thermistor malfunction

INLET THERMISTOR DIAGNOSTICS:

1

Diagnostic Checks:

• Inlet Thermistor

Control Board

2

Screws

Turn power OFF. Remove connector “R” on Control

Board. Measure resistance between Black #3 & white

#6 wires: 7K – 23K Ohms. IF OK, attempt to operate

unit again. IF 31 Error Code does NOT display, you had

a loose connection.

Molex Connectors

Blower Motor

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &

“G”. Pull Control Board out of way to access WHITE

Molex for Inlet Thermistor located near the Blower

3

Separate top and bottom of WHITE

Molex for the Inlet Thermistor. Top of

Molex has 2 black wires and 1 white

wire. Bottom of Molex has 2 white

wires. Continue to Diagnostic Chart

Bottom of Unit

on next page.

Inlet Thermistor

SVC 820-Tankless Gas Trouble Shooting Manual Page | 61

61

Clean scale build-up on Inlet Thermistor.

Retest Thermistor.

normal. Attempt to operate unit again.

YES

31 – Error Code Diagnostic Chart

Check the resistance across 2 white wires

on bottom Molex:

7K – 23K Ohms

Remove Molex from connector “R” at Control Board.

connector “R” and black wires at White Molex located

Check continuity from black #3 wire at Molex

behind Control Board. Check continuity from white

#6 wire at Molex connector “R” and white wire at

White Molex located behind Control Board

Is the resistance

to the Inlet

Thermistor OK?

IF tests OK, the water heater appears to be

NO

IF resistance NOT OK:

Replace Inlet Thermistor

Is the continuity

across all wires

OK?

YES

Attempt to operate unit again.

If the unit malfunctions due to an Error Code 31:

Replace Control Board

NO

Replace wiring harness for Connector “R”

on Control Board

62 | Page SVC 820 Tankless Gas Trouble Shooting Manual

62

Bottom of Unit

Y:

32 – Error Code

Explanation:
Heat Exchanger Thermistor malfunction

HEAT EXHCANGER THERMISTOR DIAGNOSTICS:

1

Diagnostic Checks:

• Heat Exchanger Thermistor

2

Control Board

Screws

Turn power OFF. Remove connector “R” on Control

Board. Measure resistance between Black #3 & Yellow

#5 wires: 7K – 23K Ohms. IF OK, attempt to operate

unit again. IF 32 Error Code does NOT display, unit

had a loose connection.

Molex Connectors

Blower Motor

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &
“G”. Pull Control Board out of way to access YELLOW*
Molex for Heat Exchanger Thermistor located near the

Blower Motor.

3

*High Efficiency (Condensing) Units ONL

Green wire & Green Molex

Separate top and bottom of YELLOW*

Molex for Heat Exchanger Thermistor.

Top of Molex has 2 black wires and 1
yellow* wire. Bottom of Molex has 2

white wires. Continue to Diagnostic

Chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 63

63

Clean Scale Build-Up on Heat Exchanger

Thermistor. Retest Thermistor.

normal. Attempt to operate unit again.

IF resistance NOT OK:

igh Efficiency (Condensing) Units ONLY:

32 – Error Code Diagnostic Chart

Check the resistance across 2 white wires

on bottom Molex:

7k – 23K Ohms

Remove Molex from connector “R” at Control Board.

located behind Control Board. Check continuity from

Yellow* #5 wire at Molex connector “R” and Yellow*

Check continuity from black #3 wire at Molex

connector “R” and black wire at Yellow* Molex

wire at Yellow* Molex located behind Control Board

Is the resistance

to the Heat

Exchanger

Thermistor OK?

YES

NO

IF test OK, the water heater appears to be

Replace Heat Exchanger Thermistor

*H

Green wire & Green Molex

Is the continuity

across all wires

OK?

YES

Attempt to operate unit again.

If the unit malfunctions due to an Error Code 32:

Replace Control Board

NO

Replace wiring harness for Connector “R”

on Control Board

64 | Page SVC 820 Tankless Gas Trouble Shooting Manual

64

Screws

33 – Error Code

Explanation:
Outlet Thermistor malfunction

1

Diagnostic Checks:

• Outlet Thermistor

OUTLET THERMISTOR DIAGNOSTICS:

2

Control Board

Turn power OFF. Remove connector “R” on Control
Board. Measure resistance between Black #3 & Red
#4 wires: 7K – 23K Ohms. IF OK, attempt to operate

unit again. IF 33 Error Code does NOT display, unit

had a loose connection.

Molex Connectors

Blower Motor

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &

“G”. Pull Control Board out of way to access BLACK

Molex for Outlet Thermistor located near the Blower

Bottom of Unit

Motor.

3

Separate top and bottom of BLACK

Molex for Outlet Thermistor. Top of

Molex has 2 black wires and 1 red

wire. Bottom of Molex has 2 black

wires. Continue to Diagnostic Chart

on next page.

Outlet Thermistor

SVC 820-Tankless Gas Trouble Shooting Manual Page | 65

65

Clean Scale Build-Up on Outlet Thermistor.

33 – Error Code Diagnostic Chart

Check the resistance across 2 black wires

on bottom Molex:

7k – 23K Ohms

Remove Molex from Connector “R” at Control Board.

Check continuity from black #3 wire at Connector “R”

Molex and black wires at black Molex located behind

Is the resistance

to the Outlet

Thermistor OK?

YES

Control Board. Check continuity from red #4 wire at

Connector “R” Molex and red wire at Black Molex

located behind Control Board

Is the continuity

across all wires

OK?

NO

NO

Retest Thermistor. IF tests OK, the water
heater appears to be normal. Attempt to

operate unit again. IF resistance NOT OK:

Replace Outlet Thermistor

Replace wiring harness for Connector “R”

on Control Board

If the unit malfunctions due to an Error Code 33:

YES

Attempt to operate unit again.

Replace Control Board

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66

34 – Error Code

Explanation:
Ambient Thermistor malfunction

AMBIENT THERMISTOR DIAGNOSTICS:

1

Diagnostic Checks:

• Ambient Thermistor

2

Control Board

Screws

Turn power OFF. Remove connector “R” on Control

Board. Measure resistance between Black #3 & Blue

#7 wires: ‘Refer to Data Table for resistance value’. IF

OK, attempt to operate unit again. IF 34 Error Code

does NOT display, unit had a loose connection.

Molex Connectors

Blower Motor

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &

“G”. Pull Control Board out of way to access BLUE

Molex for Ambient Thermistor located near the

Bottom of Unit

Blower Motor.

3

Separate top and bottom of BLUE

Molex for Ambient Thermistor. Top of

Molex has 2 black wires and 1 blue
wire. Bottom of Molex has 2 black

wires. Continue to Diagnostic Chart

on next page.

Ambient Thermistor Data Table

64DV; 84DV; 95DV: 7K – 23K Ohms

64X; 84X; 95X: 2K – 72K Ohms

H95DV; H95X: 2K – 72K Ohms

SVC 820-Tankless Gas Trouble Shooting Manual Page | 67

67

Clean Ambient Thermistor. Retest

34 – Error Code Diagnostic Chart

Check the resistance across 2 black wires

Ambient Thermistor Data Table

64DV; 84DV; 95DV: 7K – 23K Ohms

64X; 84X; 95X: 2K – 72K Ohms

on bottom Molex:

Refer to Data Table below

Is the resistance

to the Ambient

Thermistor OK?

YES

Remove Molex from Connector “R” at Control Board.

Check continuity from black #3 wire at Molex

connector “R” and black wires at Blue Molex located

behind Control Board. Check continuity from blue #7

wire at Molex connector “R” and blue wire at Blue

Molex located behind Control Board

Is the continuity

across all wires

OK?

NO

NO

Thermistor. IF tests OK, the water heater

appears to be normal. Attempt to operate

unit again. IF resistance NOT OK:

Replace Ambient Thermistor

Replace wiring harness for Connector “R”

on Control Board

H95DV; H95X: 2K – 72K Ohms

YES

Attempt to operate unit again.

If the unit malfunctions due to an Error Code 34:

Replace Control Board

68 | Page SVC 820 Tankless Gas Trouble Shooting Manual

68

Inlet Thermistor

Heat Exchanger Thermistor

35 – Error Code

Explanation: Improper Thermistor connection. Unit has
four Thermistors; one or more possibly has a poor
connection or not connected in proper location.

THERMISTORS DIAGNOSTICS:

1

Diagnostic Checks:

• Inlet, Heat Exchanger, Outlet, and Ambient

Thermistors.

2

Turn power OFF. Remove and reinsert connector “R”

on Control Board. Attempt to operate unit again. IF

35 Error Code does NOT display, unit had a loose

connection.

Black #3 & Blue #7 Wires: Ambient Thermistor

64DV; 84DV; 95DV: 7K – 23K Ohms

64X; 84X; 95X: 2K – 72K Ohms

H95DV; H95X: 2K – 72K Ohms

Turn power OFF. Remove connector “R” on Control

Board. Measure the resistance for all temperature

sensors (step 3). IF temperature sensor FAILS the

resistance check, go to the appropriate Error Code for

diagnostics. IF sensors test ‘OK’ continue to next page.

3

Black #3 & White #6 Wires:

7K – 23K Ohms. Error Code 31

Black #3 & Yellow #5 Wires:
7K – 23K Ohms. Error Code 32

Black #3 & Red #4 Wires: Outlet Thermistor
7K – 23K Ohms. Error Code 33

Black #3 & Blue #7 Wires: Ambient Thermistor
Refer to Data Table. Error Code 34

SVC 820-Tankless Gas Trouble Shooting Manual Page | 69

69

35 – Error Code Diagnostic Chart

Check resistance for all Thermistors at

Molex Connector “R”

Ambient Thermistor Data Table

64DV; 84DV; 95DV: 7K – 23K Ohms

64X; 84X; 95X: 2K – 72K Ohms

Is the resistance

for all

Thermistors OK?

YES

Attempt to operate the unit again

Did the unit

lockout on Error

Code 35?

NO

NO

Go to appropriate Sensor Error Code to

diagnose:

1. Inlet: Error Code 31

2. Heat Exchanger: Error Code 32

3. Outlet: Error Code 33

4. Ambient: Error Code 34

The water heater appears to be operating

normally

H95DV; H95X: 2K – 72K Ohms

YES

Replace Control Board

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70

Remove and reinsert terminals on Fame Rod(s)*.

right side of unit.

51 – Error Code

Explanation: Gas Control Valve malfunction. The unit
detects the presence of flame when the demand for hot
water is terminated and burner is OFF. This error code
will only occur at time of shut down.

Diagnostic Checks:

• Flame Rods(s)

• Gas Control Valve

FLAME RODS & GAS VALVE DIAGNOSTICS:

1 2

Turn power OFF. Remove and reinsert white

connector “M” and blue connector “T” on Control

Board.

3

Sight Glass

Attempt to operate unit again. IF 51 Error Code does

NOT display, unit had a loose connection.

Visually inspect Gas Control Valve

connections or damaged wiring.

Gas Control Valve is located on lower

*Indoor Models ONLY:

2 Flame Rods

wiring harnesses for loose

Locate sight glass.

Gas Control Valve

SVC 820-Tankless Gas Trouble Shooting Manual Page | 71

71

While viewing burner chamber through

sight glass:

heater 3 times by turning unit

“on – off; on – off; on – off”

Is debris visible

ode

ode

Attempt to operate unit again. If the unit

.

Indoor Units: 05

51 – Error Code Diagnostic Chart

In 10 second intervals; cycle the water

Visibly inspect burner chamber through

Is there a visible
flame while unit

is OFF?

YES

Sight Glass

On Remote Control, go to Maintenance Mode 0Y table. For

Maintenance Mode instructions go to page 16

All Maintenance Mode ‘0Y’ readings should be done

immediately after turning the unit OFF. IF Flame Rod(s) is

detecting flame, Maintenance Mode will display:

Outdoor Units: 01

Does ‘OY’ Status in

NO

Disconnect Molex Connector from Flame

Rods(s). Cycle the water heater 3 times by

turning unit “on – off; on – off; on – off”

Maintenance M

indicate presence

of flame after 5

seconds?

YES

Water heater appears

NO

to be normal.

Attempt to operate unit

again

on burner
assembly?

YES

Remove and clean burner assembly

Attempt to operate unit again. If the unit

displays 51 Error Code and flame IS visible while

NO

unit is OFF:

Replace Gas Control Valve

Does ‘OY’ Status in

Maintenance M

indicate presence

of flame after 5

seconds?

YES

malfunctions due to an Error Code 51:

Replace Control Board

NO

Clean or Replace Flame

Rod(s)

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72

52 – Error Code

Explanation: PGFR (Proportional Gas Flow Regulator)
malfunction. The PGFR is the only modulating valve in the
Gas Control Valve.

PGFR DIAGNOSTICS:

1

Turn power OFF. Remove and reinsert connector “R”

on Control Board.

Diagnostic Checks:

• PGFR

2

PGFR

Locate PGFR valve on lower right of unit. Remove and

reinsert Molex connector with red wire and Molex

connector with black wire on PGFR. Attempt to

operate unit again.

Control Board

Molex Connectors

3

IF 52 Error Code does NOT display,

unit had a loose connection.

IF 52 Error Code IS displayed,

continue to diagnostic chart on next

page.

PGFR

SVC 820-Tankless Gas Trouble Shooting Manual Page | 73

73

52 – Error Code Diagnostic Chart

While unit is attempting to go to main

burner, check DC voltage across red wire

#1 and black wire #2 on Connector “R”:

1.5 – 14 DC VOLTS

Is the DC voltage

OK?

YES

While unit is attempting to go to main burner, check

DC voltage across red and black wires at PGFR:

1.5 – 14 DC VOLTS

Is the DC voltage

OK?

NO

NO

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 52:

Replace Control Board

Replace wiring harness for Connector “R”

on Control Board

YES

Attempt to operate unit again.

If the unit malfunctions due to an Error Code 52:

Replace Gas Control Valve

74 | Page SVC 820 Tankless Gas Trouble Shooting Manual

74

61 – Error Code

Explanation: Blower Motor malfunction. Blower Motor
speed was not appropriate to allow proper combustion.

Diagnostic Checks:

• Blower Motor

BLOWER MOTOR DIAGNOSTICS:

1 2

Control Board

Bottom of Unit

Turn power OFF. Remove 3 screws for Control Board

Turn power OFF. Remove and reinsert connector “G”

on Control Board. Attempt to operate unit again. IF

61 Error Code does NOT display, unit had a loose

connection.

mounting bracket. Remove connectors “M”, “T” &

“G”. Pull Control Board out of way to access Blower

Motor.

Screws

3

Blower Motor

Remove 3 screws holding Blower Motor in place.

Clean Blower Motor and reassemble unit. Attempt to

operate unit again. IF 61 Error Code does NOT

display: Blower Motor needed to be cleaned.

4

Locate Min & Max buttons on Control Board.

Continue to diagnostic chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 75

75

Attempt to operate unit again.

Attempt to operate unit again.

61 – Error Code Diagnostic Chart

Test DC voltage across black and red

wires on Molex connector “G”:

144 – 192 DC VOLTS

Press and hold down “MAX” button on Control Board

test DC voltage across black and white wires on Molex

Is the DC voltage

OK?

YES

to activate Blower Motor. While Blower is running,

connector “G”:

12 – 18 DC VOLTS

Is the DC voltage

OK?

NO

NO

Remove and reinsert connector “G”.

If the unit malfunctions due to an Error

Code 61:

Replace Control Board

Remove and reinsert connector “G”.

If the unit malfunctions due to an Error

Code 61:

YES

Press and hold down “MAX” button on Control Board

to activate Blower Motor. While Blower is running,

test DC voltage across black and blue wires on Molex

connector “G”:

4 – 10 DC VOLTS

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 61:

Replace Control Board

YES NO

Is the DC voltage

OK?

Replace Control Board

Replace Blower Motor

76 | Page SVC 820 Tankless Gas Trouble Shooting Manual

76

Blower Motor

65 – Error Code

Explanation: Water Control Valve malfunction

WATER CONTROL VALVE DIAGNOSTICS:

1

Diagnostic Checks:

• Water Control Valve

Control Board

2

Screws

Turn power OFF. Remove and reinsert connector “C”

on Control Board. Attempt to operate unit again. IF

65 Error Code does NOT display, unit had a loose

connection.

Top of Unit

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”; “T” &

“G”. Pull Control Board out of way to access Water

Bottom of Unit

Control Valve.

3

Water Control Valve

Visually inspect Water Control Valve
wiring harness for loose or damaged

terminals. It is located right of the

Blower Motor; connected directly to

the water inlet. Reassemble unit and

Bottom of Unit

continue to diagnostic chart on next

page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 77

77

65 – Error Code Diagnostic Chart

While water is flowing and unit is

attempting to ignite; check DC Voltage

across White & Black Wires at

connector “C”:

8 – 16 DC VOLTS

Is the DC voltage

OK?

YES

Turn power to unit OFF then ON again and turn water

flow on. Check DC Voltage across Red & Black Wires

at connector “C”:

8 – 16 DC VOLTS

Is the DC voltage

OK?

NO

NO

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 65:

Replace Control Board

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 65:

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 65:

Replace Water Control Valve

YES

Turn power to unit OFF then ON again and turn water

flow on. Check DC Voltage across Green & Black

Wires at connector “C”:

4 – 6 DC VOLTS

Is the DC voltage

YES

OK?

NO

Replace Control Board

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 65:

Replace Control Board

78 | Page SVC 820 Tankless Gas Trouble Shooting Manual

78

Top of Unit

66 – Error Code

Explanation: Water Bypass Valve malfunction. Hot outlet
water temperature is above or below set point on Remote
Control.

WATER BYPASS VALVE DIAGNOSTICS:

•

1

Diagnostic Checks:

• Water Bypass Valve

2

Control Board

Screws

Turn power OFF. Remove and reinsert connector “B”

on Control Board. Attempt to operate unit again. IF

66 Error Code does NOT display, unit had a loose

connection.

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”; “T”; &
“G”. Pull Control Board out of way to access Water

Bottom of Unit

Bypass Valve.

3

Water Bypass Valve

Visually inspect Water Bypass Valve

wiring harness for loose or damaged

terminals. It is located right of the

Blower Motor; below two copper

Bottom of Unit

pipes. Reassemble unit and continue

to diagnostic chart on next page.

Blower Motor

SVC 820-Tankless Gas Trouble Shooting Manual Page | 79

79

connector “B”:

8 – 16 DC VOLTS

66 – Error Code Diagnostic Chart

Turn Remote Control OFF; unplug unit

and then ON again. Check DC voltage

across red and black wires on Molex

Is the DC voltage

OK?

YES

While Water Bypass Valve is operating (water is

flowing), check DC voltage across red and black wires

at Water Bypass Valve wiring harness:

8 – 16 DC VOLTS

Is the DC voltage

OK?

NO

NO

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 66:

Replace Control Board

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 66:

YES

Attempt to operate unit again. If the unit

malfunctions due to an Error Code 66:

Replace Water Bypass Valve

Replace Control Board

80 | Page SVC 820 Tankless Gas Trouble Shooting Manual

80

on lower right side of unit.

71 – Error Code

Explanation: Gas Control Valve malfunction

Diagnostic Checks: Gas Control Valve

GAS CONTROL VALVE DIAGNOSTICS:

1

Turn power OFF. Remove and reinsert connector “K” on

Control Board. Attempt to operate unit again. IF 71 Error

Code does NOT display, unit had a loose connection.

2

Gas Control Valve

Visually inspect Gas Control Valve wiring harnesses for

loose or damaged terminals. Gas Control Valve is located

Continue to diagnostic chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 81

81

71 – Error Code Diagnostic Chart

While unit is attempting to go to ignite,

check DC voltage across yellow and black

wires on Molex connector “K”:

75 – 100 DC VOLTS

Reset the water heater and attempt to operate again.

Is the DC voltage

OK?

YES

If the unit malfunctions due to an Error Code 71:

Replace Gas Control Valve

NO

Attempt to operate again.

If the unit malfunctions due to an Error

Code 71:

Replace Control Board

82 | Page SVC 820 Tankless Gas Trouble Shooting Manual

82

Remove and reinsert terminals on Flame Rod(s)*.

72 – Error Code

Explanation: Flame Rod(s) malfunction. Flame Rod(s) is
detecting the presence of flame BEFORE igniter is
activated.

Diagnostic Checks:

• Flame Rod(s)

• Gas Control Valve

FLAME ROD(s) & GAS CONTROL VALVE DIAGNOSTICS:

1 2

Flame Rod(s)*

Turn power OFF. Remove and reinsert white

connector “M” and blue connector “T” on Control

Board.

3

Gas Control Valve

Sight Glass

Attempt to operate unit again. IF 72 Error Code does

NOT display, unit had a loose connection.

*Indoor Units ONLY:

Visually inspect Gas Control Valve

wiring harnesses for loose

connections or damaged wiring.

Gas Control Valve is located on

lower right side of unit.

Locate Sight Glass.

2 Flame Rods

SVC 820-Tankless Gas Trouble Shooting Manual Page | 83

83

on water flow to begin ignition sequence

Is debris visible

ode

ode

Attempt to operate again.

ON. IF flame sensor IS detecting flame, Maintenance Mode will display:

Indoor Units: 05

72 – Error Code Diagnostic Chart

Turn power OFF. Unplug unit and plug

back in. Turn power ON. While viewing

burner chamber through sight glass, turn

Visibly inspect burner chamber through

Is there a visible

flame before

Igniter Rod

sparks?

YES

sight glass

On Remote Control, go to Maintenance Mode 0Y table. For Maintenance Mode

instructions go to page 16.

All Maintenance Mode ‘0Y’ readings should be done immediately after turning

the unit

Outdoor Units: 01

NO

Does ‘OY’ Status in

Maintenance M

indicate presence

of flame?

YES

Turn power OFF. Unplug unit. Disconnect

Molex connector(s) from Flame Rod(s).

Plug unit in. Turn power ON. Turn water

flow ON to begin ignition sequence

NO

Water heater appears

to be normal.

Attempt to operate

again

on burner
assembly?

YES

Remove and clean burner assembly

Attempt to operate again. If unit displays 72

Error Code and flame IS visible while unit is OFF:

NO

Replace Gas Control Valve

Does ‘OY’ Status in

Maintenance M

indicate presence

of flame?

YES

If unit displays 72 Error Code:

Replace Control Board

NO

Clean or Replace Flame

Rod(s)

84 | Page SVC 820 Tankless Gas Trouble Shooting Manual

84

76 – Error Code

Explanation: Communication Fault with Remote Control.
Remote Control is not communicating with Control Board

REMOTE THERMOSTAT DIAGNOSTICS:

1

Visually inspect Remote Control wiring for damaged or

loose terminals.

Diagnostic Checks:

• Remote Control

• Wiring

2

Remote Control
Wiring Terminals

Hot Water Outlet

Cold Water Inlet

Turn power OFF. Remove and reconnect Remote Control

wiring terminals at bottom of unit. Attempt to operate

unit again. IF 76 Error Code does NOT display, unit had a

loose connection.

IF 76 Error Code IS displayed, continue to diagnostic chart

on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 85

85

Did the unit go to

Did the unit go to

76 – Error Code Diagnostic Chart

Unplug unit and remove Remote

Thermostat wires from wiring terminals

on bottom of unit. Plug unit in and open

a hot water source.

main burner?

YES

Unplug unit. Use a short piece of new thermostat

wire to connect the Remote Control directly to

Remote Control wiring terminals at bottom of unit.

Plug unit in and open a hot water source.

main burner?

NO

NO

Attempt to operate unit again. If the unit

malfunctions due to an Error Code 76:

Replace Remote Control

Replace Remote Control

YES

The wiring is defective. Replace Remote Control

wiring.

86 | Page SVC 820 Tankless Gas Trouble Shooting Manual

86

79 – Error Code

Explanation: Blower Motor current fault. The unit
detected a fault with the Blower Motor.

Diagnostic Checks:

• Blower Motor

BLOWER MOTOR DIAGNOSTICS:

1 2

Control Board

Bottom of Unit

Screws

Turn power OFF. Remove and reinsert connector “G”

on Control Board. Attempt to operate unit again. IF

79 Error Code does NOT display, unit had a loose

connection.

3

Blower Motor

Remove 3 screws holding Blower Motor in place.

Clean Blower Motor and reassemble unit. Attempt to

operate unit again. IF 79 Error Code does NOT

display: Blower Motor needed to be cleaned.

Turn power OFF. Remove 3 screws for Control Board

mounting bracket. Remove connectors “M”, “T” &

“G”. Pull Control Board out of way to access Blower

Motor.

4

Locate Min & Max buttons on Control Board.

Continue to diagnostic chart on next page.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 87

87

Remove and reinsert connector “G”.

Attempt to operate unit again.

18 DC VOLTS

Attempt to operate unit again.

79 – Error Code Diagnostic Chart

Test DC voltage across black and red

wires on Molex connector “G”:

144 – 192 DC VOLTS

Press and hold down “MAX” button on Control Board

test DC voltage across black and white wires on Molex

to activate Blower Motor. While Blower is running,

Is the DC voltage

OK?

YES

connector “G”:

12 –

NO

IF the unit malfunctions due to an Error

Code 79:

Replace Control Board

Attempt to operate unit again.

If the unit malfunctions due to an Error

Code 79:

Is the DC voltage

OK?

YES

Press and hold down “MAX” button on Control Board

to activate Blower Motor. While Blower is running,

test DC voltage across black and blue wires on Molex

connector “G”:

4 – 10 DC VOLTS

Is the DC voltage

YES NO

OK?

NO

Remove and reinsert connector “G”.

If the unit malfunctions due to an Error

Code 79:

Replace Control Board

Replace Blower Motor

Replace Control Board

88 | Page SVC 820 Tankless Gas Trouble Shooting Manual

88

Remove and reinsert terminals on Flame Rod(s)*.

80 – Error Code

Explanation: Gas Control Valve malfunction. The unit
detects the presence of flame when the demand for hot
water is terminated and burner is OFF. This error code will
only occur at time of shut down.

Diagnostic Checks:

• Flame Rod(s)

• Gas Control Valve

FLAME ROD(s) & GAS CONTROL VALVE DIAGNOSTICS:

1 2

Flame Rod(s)*

Turn power OFF. Remove and reinsert white

connector “M” and blue connector “T” on Control

Board.

3

Sight Glass

Attempt to operate unit again. IF 80 Error Code does

NOT display, unit had a loose connection.

*Indoor Units ONLY:

Visually inspect Gas Control Valve wiring

harnesses for loose connection or

damaged wiring. Gas Control Valve is

located on lower right side of unit. Locate

2 Flame Rods

Sight Glass.

Gas Control Valve

SVC 820-Tankless Gas Trouble Shooting Manual Page | 89

89

to be normal.

While viewing burner chamber through

sight glass:

heater 3 times by turning unit

“on – off; on – off; on – off”

Is debris visible

ode

ode

Attempt to operate unit again.

Indoor Units: 05

80 – Error Code Diagnostic Chart

In 10 second intervals; cycle the water

Visibly inspect burner chamber through

Is there a visible
flame while unit

is OFF?

YES

sight glass

On Remote Control, go to Maintenance Mode 0Y table. For Maintenance

Mode instructions go to page16.

All Maintenance Mode ‘0Y’ readings should be done immediately after

turning the unit OFF. IF Flame Rod(s) is detecting flame, Maintenance Mode

will display:

Outdoor Units: 01

NO

Does ‘OY’ Status in

Maintenance M

indicate presence

of flame after 5

seconds?

YES

Disconnect Molex Connector from Flame

Rod(s). Cycle heater 3 times by turning

unit “on – off”; “on – off”; “on – off”

NO

Water heater appears

Attempt to operate

again

on burner
assembly?

YES

Remove and clean burner assembly

Attempt to operate again. If unit displays 80

Error Code and flame IS visible while unit is OFF:

NO

Replace Gas Control Valve

Does ‘OY’ Status in

Maintenance M

indicate presence

of flame after 5

seconds?

YES

If unit displays 80 Error Code:

Replace Control Board

NO

Clean or Replace Flame

Rod(s)

90 | Page SVC 820 Tankless Gas Trouble Shooting Manual

90

unit again.

82 – Error Code

Explanation: Control Board Program Chip malfunction

PROGRAM CHIP DIAGNOSTICS:

1

Diagnostic Checks:

• Program Chip

2

Turn power OFF. Verify you have a Program Chip inserted

in connector “A”.

Remove and reinsert Program Chip. Attempt to operate

IF unit does NOT display 82 Error Code, unit had a loose

connection.

SVC 820-Tankless Gas Trouble Shooting Manual Page | 91

91

90 – Error Code

Explanation: The unit detected blockage in the venting during pre-purge cycle. This Error Code will occur BEFORE unit goes to
ignition.

Possible Causes:

• VENTING

VENTING:

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

6. Venting Not Sealed Properly

**REFER TO USE & CARE MANUAL**

92 | Page SVC 820 Tankless Gas Trouble Shooting Manual

92

92 – Error Code

Explanation: High Efficiency Condensing Units ONLY. This is a warning code and unit will continue to
operate but will eventually shut down due to an error code 93. REPLACE NEUTRALIZER ASAP.

*

Once Neutralizer is replaced; follow reset procedures on page 21.

93 – Error Code

Explanation: High Efficiency Condensing Units ONLY. Unit will NOT operate until the Neutralizer
Medium is replaced. REPLACE NEUTRALIZER IMMEDIATELY.
Neutralizer rocks made from Calcium Carbonate (CACO
Neutralizer Kit may be ordered through Rheem Supplier.

*

Once Neutralizer is replaced; follow reset procedures on page 21.

3).

Neutralizer

SVC 820-Tankless Gas Trouble Shooting Manual Page | 93

93

6. Venting Not Sealed Properly

99 – Error Code

Explanation: The unit detected blockage in the venting during post-purge cycle. Blockage was detected when the demand for
hot water terminated and burner was OFF. This error code will only occur at time of shut down.

*Unit must be reset by performing reset procedure on page 21.

Possible Causes:

• Venting

**REFER TO USE & CARE MANUAL**

VENTING:

Visually inspect venting for possible blockage and/or recirculation of exhaust.

1. Approved Venting Materials

2. Approved Vent Terminations

3. Vent Lengths

4. Location Of Vent Termination (Recirculation of exhaust)

5. Blocked Venting

94 | Page SVC 820 Tankless Gas Trouble Shooting Manual

94

NOTES:
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SVC 820-Tankless Gas Trouble Shooting Manual Page | 95

95

NOTES:
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R

Tankless Gas Water Heaters

High Effi ciency Condensing Models
PHH-25ROFN & PHH-32ROFN (Outdoor Natural Gas Models)
PHH-25ROFP & PHH-32ROFP (Outdoor L.P. Gas Models)
PHH-25RDVN & PHH-32RDVN (Indoor Direct Vent Natural Gas Models)
PHH-25RDVP & PHH-32RDVP (Indoor Direct Vent L.P. Gas Models)

Mid Effi ciency Models
PH2-20ROFN, PH2-25ROFN & PH2-28ROFN (Outdoor Natural Gas Models
PH2-20ROFP, PH2-25ROFP & PH2-28ROFP (Outdoor L.P. Gas Models)
PH2-20RDVSN, PH2-25RDVSN & PH2-28RDVSN
(Indoor Direct Vent Natural Gas Models)
PH2-20RDVSP, PH2-25RDVSP & PH2-28RDVSP
(Indoor Direct Vent L.P. Gas Models)

Second Section
Information Guide

- 96 -

- 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 for Second Section

- 97 -

Page

Specifi cations .................................................................. 98 ~ 99

External Dimensions ...................................................... 100 ~ 101

Schematic Construction ................................................. 102 ~ 105

Operational Principle ..................................................... 106 ~ 111

Capacity ......................................................................... 112 ~ 120

Wiring Diagram ............................................................. 121 ~ 122

Thermistor Resistance Chart .......................................... 123

Adjustment ..................................................................... 124 ~ 132

DUOnex Cable ............................................................... 133 ~ 136

MIC-185 ......................................................................... 137 ~ 146

MIC-6 ............................................................................. 147 ~ 154

Commercial Conversion ................................................ 155 ~ 157

Schematic Disassembly and Parts List .......................... 158 ~ 171

SPECIFICATIONS (Approx.)

Model PH2-20R OFN, PH2-20R OFP,

PH2-25R OFN, PH2-25R OFP
PH2-28R OFN, PH2-28R OFP

PH2-20R DVSN, PH2-20R DVSP
PH2-25R DVSN, PH2-25R DVSP

PH2-28R DVSN, PH2-28R DVSP
Purpose Domestic Hot Water Supply
Rated Gas Input

(Btu/Hr.)

11,000 (Min.) ~ 150,000 (Max.) (PH2-20R Series) Modulating
11,000 (Min.) ~ 180,000 (Max.) (PH2-25R Series) Modulating
11,000 (Min.) ~ 199,900 (Max.) (PH2-28R Series) Modulating

Dimensions (in.) 13 7/8 (W) x 23 5/8 (H) x 8 7/8 (D) 13 7/8 (W) x 25 5/8 (H) x 9 7/8 (D)
Net Weight (lbs.) 60

Installation Outdoor W all Mounting Type Direct Vent Indoor Wall Mounting Type

Can be vented either horizontally or vertically
Working Water Pressure 14 psi ~ 150 psi
Minimum Water Flow 0.40 GPM
Maximum Flow Rate 6.4 GPM (PH2-20R); 8.4 GPM (PH2-25R); 9.5 GPM (PH2-28R) at 35ºF Temp. Rise
Gas Connection 3/4” NPT Female (w/supplied Gas Shutoff Valve)
Water Connection 3/4” NPT Male
Vent Size N/A (Outdoor Installation) 3”/5” Concentric Special Venting (Category III)
Max. Vent Length N/A (Outdoor Installation) 36 Feet with 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. 13.0” w.c. (Do not exceed maximum pressure.)

Hot Water Supply Adjusting Range 85ºF ~ 120ºF (140ºF) (Residential)

Adjusting Range 85ºF ~ 185ºF (Commercial) (By conversion kit)
Max. Setting W/ Main Remote Control (UMC-117) & Adjustment

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

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

Safety Devices Oxygen Depletion Safety Sensing Burner (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-185 for Multi-Unit System Controller (2 to 6 units); MICS-180 for Expansion Board

(Up to 20 units); Communication Cables for MIC-185 (16, 32 & 65 feet)

MIC-6 for Manifold Controller (2 to 6 units); Manifold Cables for MIC-6 (6 & 18 feet)
High Altitude Setting High Altitude DIP Switch Adjustment

Hot Water Flow Rate and Temperature Rise

Temp. Rise (ºF)

35

45 50 60 70 80 90 100

Water Flow (GPM) PH2-20R 6.4 5.6 5.1 4.2 3.6 3.2 2.8 2.5
Water Flow (GPM) PH2-25R 8.4 6.7 6.1 5.1 4.3 3.8 3.4 3.0
Water Flow (GPM) PH2-28R 9.5 7.4 6.6 5.5 4.7 4.1 3.7 3.3

- 98 -

Note: Special Venting: The adapter, vent pipe, elbow, vent terminal, etc. should be UL 1738 Certifi ed Category III Stainless
Steel Venting Materials . “B” vent is not permitted.
Since we are constantly improving our products, all specifi cations are subject to change without notice.

SPECIFICATIONS (Approx.)

Model PHH-25ROFN, PHH-25ROFP

PHH-32ROFN, PHH-32ROFP

PHH-25RDVN, PHH-25RDVP

PHH-32RDVN, PHH-32RDVP
Purpose Domestic Hot Water Supply
Rated Gas Input

(Btu/Hr.)

11,000 (Min.) ~ 157,000 (Max.) (PHH-25R Series) Modulating
11,000 (Min.) ~ 199,900 (Max.) (PHH-32R Series) Modulating

Dimensions (in.) 18 1/2 (W) x 27 5/8 (H) x 9 3/4 (D) 18 1/2 (W) x 30 3/8 (H) x 9 3/4 (D)
Net Weight (lbs.) 76

Installation Outdoor W all Mounting Type Direct Vent Indoor Wall Mounting Type

Can be vented either horizontally or vertically
Working Water Pressure 14 psi ~ 150 psi
Minimum Water Flow 0.40 GPM
Maximum Flow Rate 8.5 GPM (PHH-25R); 9.5 GPM (PHH-32R) at 35ºF Temp. Rise
Gas Connection 3/4” NPT Female (w/supplied Gas Shutoff Valve)
Water Connection 3/4” NPT Male
Vent Size N/A (Outdoor Installation) 2” or 3” PVC or CPVC
Max. Vent Length N/A (Outdoor Installation) 35 Feet with Three 90º Elbow (3” PVC)

5 Feet with One 90º Elbow (2” PVC)
Effi ciency Rating 93% (PHH-25ROF, PHH-32ROF, PHH-32RDV); 94% (PHH-25RDV)
Energy Factor 0.93 (PHH-25ROF); 0.94 (PHH-25RDV, PHH-32ROF, PHH-32RDV)
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. 13.0” w.c. (Do not exceed maximum pressure.)

Hot Water Supply Adjusting Range 85ºF ~ 120ºF (140ºF) (Residential)

Adjusting Range 85ºF ~ 185ºF (Commercial) (By conversion kit)
Max. Setting W/ Main Remote Control (UMC-117) & Adjustment

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

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

Safety Devices Oxygen Depletion Safety Flame Rod (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-185 for Multi-Unit System Controller (2 to 6 units); MICS-180 for Expansion Board

(Up to 20 units); Communication Cables for MIC-185 (16, 32 & 65 feet)

MIC-6 for Manifold Controller (2 to 6 units); Manifold Cables for MIC-6 (6 & 18 feet)
High Altitude Setting High Altitude DIP Switch Adjustment

Hot Water Flow Rate and Temperature Rise

Temp. Rise (ºF)

35

45 50 60 70 80 90 100

Water Flow (GPM) PHH-25R 8.5 6.6 5.9 4.9 4.2 3.7 3.3 3.0
Water Flow (GPM) PHH-32R 9.5 8.4 7.6 6.3 5.4 4.7 4.2 3.8

- 99 -

Note: Venting: Schedule 40 (PVC), Schedule 40 (CPVC) or Category III Stainless Steel . “B” vent is not permitted.
Since we are constantly improving our products, all specifi cations are subject to change without notice.

EXTERNAL DIMENSIONS

(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)

13 7/8” (350 mm)

12 15/16” (328 mm)

3 1/2” (90 mm)

25 3/16” (640 mm)

23 5/8” (600 mm)

22 3/8” (568 mm)

2 7/8” (72.5 mm)

2 15/16” (73 mm)

5 3/16” (132 mm)

1 1/8” (28 mm)

5” (127 mm)

2 1/16” (53 mm)

2 1/4” (58 mm)

5 1/4” (134 mm)

7/16” (10.5 mm)

8 7/16” (215 mm)

3/8”
(10 mm)

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)

For Power Cord

For Remote Control
Connection

(PH2-20ROF, PH2-25ROF & PH2-28ROF Outdoor Models)

13 7/8” (350 mm)

12 15/16” (328 mm)

5 1/8” (130 mm)

3”/5” Concentric

9 7/16” (240 mm)

5 1/8” (131 mm)

3/8” ~ 1 9/16”
(10 ~ 40 mm)

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)

3” (100.5 mm)

5 3/16” (132 mm) 5” (127 mm)

1 1/8” (28 mm)

7 7/8” (200 mm)

4 3/16” (107 mm)

3 3/8” (86 mm)

3 5/8” (92 mm)

26 7/16” (672 mm)

25 5/8” (650 mm)

24 3/8” (618 mm)

(PH2-20RDVS, PH2-25RDVS &
PH2-28RDVS Direct Vent Models)

- 100 -