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.

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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

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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

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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.