Lochinvar Power-fin 502 User manual

Service Manual
Models: 502, 752, 1002, 1302,
1501, 1701, and 2001
Up To 5:1 Turndown
This manual must only be used
by a qualified heating installer /
service technician. Read all
instructions, including this
manual and the Power-fin
Installation and Operation
Manual, before installing.
Perform steps in the order given.
Failure to comply could result in
severe personal injury, death, or
substantial property damage.
WARNING
Save this manual for future reference.

2
Service Manual
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Hazard definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Please read before proceeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What is in this manual? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Troubleshooting Chart - No Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Checking Temperature Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Troubleshooting Chart - Noisy System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Troubleshooting Chart - Fault Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Revision Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Back Cover
Contents
Hazard definitions
The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk
levels or to important information concerning the life of the product.
DANGER
WARNING
CAUTION
CAUTION
NOTICE
DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or
serious injury.
WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or
serious injury.
CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or
moderate injury.
CAUTION used without the safety alert symbol indicates a potentially hazardous situation which, if not
avoided, may result in property damage.
NOTICE indicates special instructions on installation, operation, or maintenance that are important but
not related to personal injury or property damage.

Service Manual
Please read before proceeding
Installer – Read all instructions,
including this manual and the Power-fin
Installation and Operation Manual,
before installing. Perform steps in the
order given.
User – This manual is for use only by a
qualified heating installer/service
technician. Refer to the Power-fin User’s
Information Manual for your reference.
Have this appliance serviced/inspected
by a qualified service technician at least
annually.
Failure to comply with the above could
result in severe personal injury, death or
substantial property damage.
When calling or writing about the
appliance – Please have the appliance
model and serial number from the
appliance’s rating plate.
Consider piping and installation when
determining appliance location (see the
Power-fin Installation and Operation
Manual).
Any claims for damage or shortage in
shipment must be filed immediately
against the transportation company by
the consignee.
3
WARNING
NOTICE
When servicing appliance –
• To avoid electric shock, disconnect electrical supply
before performing maintenance.
• To avoid severe burns, allow appliance to cool before
performing maintenance.
Appliance operation –
• Do not block flow of combustion or ventilation air to
the appliance.
• Should overheating occur or gas supply fail to shut off,
do not turn off or disconnect electrical supply to
circulator. Instead, shut off the gas supply at a location
external to the appliance.
• Do not use this appliance if any part has been under water.
The possible damage to a flooded appliance can be
extensive and present numerous safety hazards. Any
appliance that has been under water must be replaced.
Appliance water –
• Thoroughly flush the system (without appliance
connected) to remove sediment. The high-efficiency
heat exchanger can be damaged by build-up or
corrosion due to sediment.
• Do not use petroleum-based cleaning or sealing
compounds in the appliance system. Gaskets and seals in
the system may be damaged. This can result in
substantial property damage.
• Do not use “homemade cures” or “appliance patent
medicines”. Serious damage to the appliance, personnel,
and/or property may result.

4
Service Manual
What is in this manual?
Service
The Power-fin display
• Display panel readout, buttons and their functions
Control module inputs
• Control module inputs and options
Control module outputs
• Control module outputs and options
General
• How the appliance operates
• How the control module operates
• Access modes -- user and installer
• Sequence of operation -- Domestic Hot Water
(DHW)/space heating
Control panel menu access
• Accessing programming mode and locating menus
(See separate guides covering the PC and pocket PC
interfaces)
Control panel parameter access
• Accessing and changing parameters from the display panel
Quick start information -- parameter table
• An index of available adjustments and readouts, where to
access them and where to find detailed information.
Power-fin operation
• A: General
• B: Temperature Setting
• C: Data Logging
• D: Functions
• E: DHW Settings
• F: Outdoor Air Reset Curve
• G: Anti-cycling
• H: Control Modes
• I: Cascade
• J: Building Management System (BMS)
• K: Circulation Pumps
• L: Service Notification
Maintenance
• Service and maintenance schedules
• Address reported problems
• Inspect appliance area and appliance interior
• Clean condensate trap
• Check all piping for leaks
• Flue vent system and air piping
• Check water system
• Check expansion tank
• Check control settings
• Check igniter
• Check all appliance wiring
• Check flue gas passageways
• Flame inspection
• Inspect and clean burner
• General maintenance
• Checking manifold gas pressure
• Combustion analysis procedure
• Gas valve adjustment procedure
• Cleaning heat exchanger
• Review with owner
Troubleshooting
• Troubleshooting table - No display
• Checking temperature sensors
• Troubleshooting table - Noisy system
• Troubleshooting table - Fault messages displayed on
Operator Interface

1 Service
Service Manual
5
The Power-fin display

1 Service
6
Service Manual
Control inputs

Service Manual
7
Control outputs
1 Service (continued)

1 Service
8
Service Manual
General Operation
How the appliance operates
The Power-fin uses a copper-finned tube heat exchanger to
transfer heat from the flue products to the water. An electronic
control module monitors various inputs to initiate a call for
heat. The blower provides both primary and secondary air to
the burner and forces the flue products out of the combustion
chamber and into the vent system. The control module
regulates the blower speed (on B9 and M9 models) to control
the firing rate of the appliance. The modulating gas valve
monitors the amount of combustion air being pulled into the
blower and regulates the amount of gas supplied, which then
mixes with the combustion air and is supplied to the burner.
How the control module operates
The Power-fin control module receives input from appliance
sensors. The control module activates and controls the blower
and gas valve to regulate heat input and switches heater, DHW
and system pumps on and off as needed. The user/installer
programs the module to meet system needs by adjusting control
parameters. These parameters set operating temperatures and
heater operating modes. Appliance operation can be based on
heater outlet water temperature, heater return water
temperature, system supply temperature, system return
temperature or tank temperature, depending on the parameter
setting.
Sequence of operation
Table 1A shows control module normal sequences of operation
for space heating and DHW operation. The combined
operation sequence is for a typical application, programmed to
provide DHW priority.
Access modes
User
The user can adjust space heating set point using the UP and
DOWN buttons at any time during normal operation. By
entering the USER code (0704), the user can also change
temperature units, time and date, and night setback settings. In
user mode, the following parameters can be viewed but not
changed: Heater outlet water temperature in DHW mode;
heater model number; software version; total operating hours,
and total cycles.
Installer
Most parameters are available only to the installer, accessible
only by entering the installer access code (5309).
Saving parameters
To save parameters and exit programming:
Press the ENTER/RESET button, then the MENU/EXIT button
3 times.
To keep parameter settings only for a current operating cycle:
Press the MENU/EXIT button 3 times after making all desired
parameter changes.
To enter a parameter and continue programming:
Press the MENU/EXIT button 1 time to return to the parameter
listings; press again to return to the menu listings. Remember to
press the ENTER/RESET button when finished programming in
order to save the changes made.

Service Manual
9
Sequence of operation
Table 1A_Sequence of Operation - Space Heating and DHW
1 Service (continued)
OOPPEERRAATTIIOONNDDIISSPPLLAAYY
1. The manual reset high limit must be closed before any
action will take place.
HTR: Standby
OUT: 123.8F(129)
2. Upon a call for heat the control turns on the appropriate
pumps (system and boiler pumps for space heating; DHW
pump for DHW call). The flow switch and low water cutoff (if
equipped) must close.
HTR: Standby
OUT: 123.8F(129)
3. • If the unit is equipped with a proof of closure valve, the
proof of closure switch must be closed. The proof of
closure valve is then energized. The gas pressure
switch(es) (if equipped) must close.
• If the contact for the louvers is closed, the louver proving,
blocked drain switch, and auto reset high limit (water
heater only) inputs must close.
• If the air pressure switch is open, the prepurge cycle then
begins by starting the combustion blower. Once started,
the air pressure switch must close.
HTR: Standby
OUT: 123.8F(129)
4. After the 10 second prepurge, the blower slows down and
the hot surface igniter (HSI) is energized. The HSI is heated
for at least 15 seconds.
HTR: PREPURGE
OUT: 123.9F(129)
5. Once the HSI is hot, the trial for ignition begins with the
opening of the gas valve.
HTR: IGNITION
OUT: 123.9F(129)
6. If the SMART SYSTEM control does not sense flame within
7 seconds of the opening of the gas valve, then it will lock
out.
HTR: POSTPURGE, PREPURGE
OUT: 123.9F(129)
7. If the SMART SYSTEM control senses flame within 7
seconds, it will fire the burner to maintain the set point. On
B9 and M9 models, the firing rate will modulate as required
to hold the actual temperature at the set point. If the boiler
lights due to a space heating call for heat, and the ramp
delay function is active (default is disabled), the modulation
will be held to a series of increasing limits after the burner
has lit.
HTR: SH 20% RATE
OUT: 124.8F(129)
8. If the space heating call for heat is active, and the DHW
thermostat closes, the control will turn on the DHW pump,
wait 2 seconds, and then turn off the boiler pump. This will
divert the hot water away from the heating zone(s) and send
it to the DHW tank instead. The control will then modulate
(B9 and M9 models only) to maintain the outlet temperature
to the DHW boiler set point.
HTR: DHW 85% RATE
OUT: 177.8(180)

1 Service
10
Service Manual
Sequence of operation
Table 1A_(continued from previous page) Sequence of Operation - Space Heating and DHW
OOPPEERRAATTIIOONNDDIISSPPLLAAYY
9. If the DHW thermostat remains on for more than
30 minutes, and the space heating call for heat is also on,
then the control will turn on the boiler pump, turn off the
DHW pump after 2 seconds, and resume firing based on the
space heating set point. As long as both the space heating
and DHW calls for heat remain active, the control will switch
back and forth between the two modes until one of them is
satisfied.
HTR: SH 41% RATE
OUT: 123.0F(129)
10. Once both calls for heat are satisfied, the control will turn
off the burner. The blower will remain on for the
30 second postpurge cycle. Any pumps that are running
will continue to run for their respective pump delay times,
then turn off.
HTR: POSTPURGE
OUT: 127.4F(129)
11. Boiler pump off, system pump continues its delay if
longer.
HTR: Standby
OUT: 124.7F(129)
12. System pump off. HTR: Standby
OUT: 122.9F(129)