Keystoker Koker User manual

© June 2019 REV 4
Installation, Operation and Maintenance
Manual
Koker, Koker Lite & Econo 90
Stoker Coal Stoves
Koker Stove Shown

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 2 -
About Us
Keystoker had its inception in 1946.
Two electrical engineers saw the need for a way to conveniently burn anthracite coal,
which was plentiful, but heating with coal had a bad reputation of being dirty and
requiring maintenance several times a day. Our engineers developed an automatic
stoker unit equipped with a coal hopper that held enough fuel for several days. This
allowed the coal to be cleanly burned and without frequent maintenance. They then
saw the need to make a hot water boiler specifically designed to burn coal and built
them in multiple sizes to meet our customers' needs.
As prices of energy continued to escalate, Keystoker continued its research. Over 60
years of research has developed a patented feed-in system, a patented flat grate, and
a patented thermal heat exchange, which has produced the highest efficiency
possible.
Keystoker --- Made in America with American Technology and utilizing American
resources is now known internationally for its simplicity, quality, and dependability, all
this and still an economical price.
Tested 7/05 TO UL 391, TESTED 8/03 TO CSA B366-m1979
CONAM Inspection, Inc.
Auburn, MA 01501 STL-002

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 3 -
Table of Contents
Safety
4
Precautions & Definitions
4
General Safety Statements
4
Installation
5
Stove Placement
5
Assembly
6
Fuel Type
6
Operation
7
Start-up
7
Check Draft
7
Diagram 1 - Continuous Heating
8
Diagram 2 – Intermittent Heating
9
Component Descriptions & Operation
10
Stoker Unit Components
10
Timer
13
Thermostat
14
Fan Limit Switch
14
Maintenance
15
Cleaning & Lubrication of Stove
15
Cleaning Stove Glass (not available with all models)
15
Ash Pan Emptying
16
Gear Motor Removal & Installation
17
Troubleshooting Guide
19
Diagrams
21
Wiring – Honeywell Relay & Airotronics Timer
21
Wiring – Direct Vent, Honeywell Relay & Airotronics Timer
22
Wiring – Taco Relay & Airotronics Timer
23
Wiring – Direct Vent, Taco Relay & Airotronics Timer
24
Stove Parts List
25
Fire Door & Ash Door Parts Lists
26
Ductwork Configurations – Recommended
27
Ductwork Configurations – Not Recommended
29
Warranty
30
Stove Information
30
Parts Ordering
30
Stove Contents Checklist
31

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 4 -
Safety
Precautions & Definitions
Our stoves have been designed for safe and reliable operation when properly used
and maintained in accordance with instructions contained in this manual. A stoker
stove is a precision system that if not properly installed or maintained can be hazardous,
cause burns, electrical shock or even loss of life. Keystoker shall not be liable for
physical injury, damage to property or death caused by a failure to observe the
instructions in this manual.
Please note the following symbols are used to denote special attention within this
manual:
Electrical Hazard. Particular care must be taken when electrical power source to
the unit is energized.
Warning. Operating procedure, practice etc. which, if not correctly followed,
could result in personal injury.
Caution. Operating procedure, practice etc. which if not followed could result in
damage or destruction of unit.
Fire. Operating procedure, practice, etc. which if not followed could result in
severe burns, bodily harm, loss of life and property damage.
Death. Critical situation or operation of unit that may cause death.
General Safety Statements:
•Thoroughly read and understand all instructions
•Always leave this manual with the owner of the stove.
•A carbon monoxide (CO) detector has been supplied with your stove.
oThe CO Detector needs to be plugged in.
oCO is colorless, odorless & tasteless gas that can be deadly if not
monitored or detected properly.
•Danger risk of fire or explosion. Do not burn garbage, gasoline, drain oil, or other
flammable liquids. Do not use chemicals or fluids to start fire.
•Stove surfaces may be hot while in operation. Keep children away. Do not touch
during operation
•Do not connect this unit to a chimney flue serving another appliance
•Please follow all local building and Zoning ordnances
•Use the proper fuel type as noted in this manual

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 5 -
Installation
Stove Placement
1. Select a position on a solid level surface with direct access to a chimney. On
non-masonry floors, use an approved fire resistant & ember resistant floor
protector under stove. Maintain 16” clearance on sides of stove to combustibles.
Zero clearance on rear and 16” clearance on front of stove. Clearance from
corners of stove is 8”. See label on stove. Refer to Figure 1.
FIGURE 1
•Tested 7/05 TO UL 391, TESTED
8/03 TO CSA B366-m1979
•Chimney Type: Minimum 6”
diameter approved low heat
residential type all fuel.
•Chimney connector: 6” diameter
24 gauge blue or black steel.
•Install at least 18 inches from
ceiling special methods are
required when passing through a
wall or ceiling

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 6 -
Assembly
1. Plumb hopper end of stove with level. Hopper end of stove must be vertical.
2. On bottom vent models, mount timer on side or rear of coal hopper.
3. Mount hopper in place and fasten securely. Carefully, reach down into bottom
of inside hopper and bend flange of hopper into throat of stoker unit.
4. Ensure all power for this unit is turned off. Locate thermostat in an area where
heat from stove can be freely reached. Mount plastic wall plate of thermostat.
Connect thermostat wires to screws on lower portion of wall plate. According to
instructions, run terminal Red & White thermostat wires to Relay on stove and
connect wires to terminals marked T.T. (note: color coding of thermostat wires is
unimportant.) Be sure to snap thermostat securely onto wall plate.
5. Install stove pipe from stove to chimney and secure with screws. On top vent
models, place the non crimped end of pipe of barometric damper down onto
the 6” exhaust outlet on stove. Swinging door on barometric damper may face
any direction; however, the hinges must be horizontal.
a. High chimneys or high winds could cause stove to operate inefficiently
and could possibly damage stove mechanism. It is therefore necessary
that you install the barometric damper that is supplied with your stove. All
top vent stoves are required to use an automatic damper.
6. Ensure all terminals are properly connected. Plug power cord into 110 volt
grounded wall outlet. Combustion blower should be running. Turn the thermostat
up to make the feed motor operate and you are now ready to start a fire.
Fuel Type
1. Burn rice Anthracite coal only.
Danger risk of fire or explosion. Do not burn garbage, gasoline, drain oil, or other
flammable liquids. Do not use chemicals or fluids to start fire.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 7 -
Operation
Startup
1. To start a fire, fill hopper with coal, reach in through fire door and pull coal
down to cover entire grate area. Place kindling (charcoal supplied) into a full
sheet of newspaper, crumble paper, and dig kindling deep into coal in the
center of grate. Light newspaper with match and plug power cord into
outlet. NEVER USE GASOLINE OR LIGHTER FLUID TO START FIRE. When kindling is
burning well, place a few small shovel full of coal onto the fire.
NOTE: The coal feeder adjustment nut is PRESET and may not need to be
changed. If it becomes necessary to adjust coal feed, the white nut on stoker
unit may be turned CLOCKWISE for MORE coal feed and COUNTER-CLOCK WISE
for LESS coal feed. NEVER USE A WRENCH ON COAL FEED ADJUSTMENT NUT (USE
FINGERS ONLY).
Check Draft
After starting a fire and a consistent fire is established, the chimney will be warm
enough to check draft.
1. Remove Allen screw located in ash door and insert draft gauge into hole in ash
door. The draft range should not go lower than -.02, nor above -.03. The air
shutter on combustion motor and/or the barometric damper on stove pipe may
be used to obtain proper draft readings.
a. If draft goes above -.03 adjust barometric damper to open a little wider.
b. If draft goes below -.02 close air shutter on combustion motor.
c. Check for debris in exhaust chamber & stack.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 8 -
Diagram 1 – Continuous Heating
Depicts what fire should look like when thermostat calls for heat for extended period:
A. Unburned fresh coal supply from coal hopper
B. Burning Coals
C. Ash on end of grate (around 1” to 2”)
The actual length of burning coals will vary as heat demand increases or decreases. If
burning coals fall off grate, reduce coal feed by turning white adjustment nut in a
counter clock-wise direction 1 or 2 full turns. Wait at least 1 hour before making any
more adjustments.
When thermostat is calling for heat, the gear motor will be in continuous run, but if the
fire bed remains small, increase the coal feed by turning white adjustment nut clock-
wise.
Under normal draft conditions, when fire bed has reached its maximum length (with 2”
of ash) flames should be touching top of interior stove plate. If flame is not reaching top
of stove:
1. Fire bed may be too thick.
2. Reduce coal feed.
3. Hopper end of stove is not plumb.
4. Burrs may be stuck on grate, scrape grate until it is smooth.
5. Not enough air flow, adjust air intake shutter on combustion motor
(see Check Draft section).
A.
UNBURNED
COAL
B.
FIRE
C.
ASH
DIAGRAM 1

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 9 -
Diagram 2 – Intermittent Heating
Depicts what fire size should look like when thermostat has not called for heat for
extended periods:
A. Unburned fresh coal supply from hopper.
B. Burning coal (about 1-1 ½” to 2”) (low flames).
C. Ash on end of grate
A.
UNBURNED
COAL
B.
FIRE
C.
ASH
DIAGRAM 2

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 10 -
Component Descriptions & Operation
Stoker Unit Components (for Koker shown)
Item #
Component
Item #
Component
1
Stoker Subframe
10
1
Stoker Grate # 2
2
Side Rail, Left
11
1
Stoker Grate # 4
3
Side Rail, Right
12
Screw, ¼-20UNC x 2.00” Long
4
Washer, 5/16”
13
Square Nut, ¼”
5
Nut, 5/16”
14
Pusher Bar Subassembly
6
1
Combustion Blower
15
Top Plate Subassembly
7
Coal Level Plate
16
Drive Screw ½” x ¾” Long
8
Screw, #10-24UNC x ½” Long
17
1
Stoker Motor Subassembly
9
1
Stoker Grate # 1
FIGURE 2
1Components shown will vary in size and quantity for the Koker Lite and Econo 90 Stoves

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 11 -
PUSHER BAR SUBASSEMBLY: Moves in a reciprocating motion. Activated by cam on gear
motor to force coal from hopper onto grate and pushes ashes off grate into ash pan.
Length of stroke is adjustable by turning white coal feed adjustment nut. Replaceable
parts include Nylon Screws (#5 & #6) & Insulation Strip (#7). All other parts are non-
serviceable.
Item #
Component
Item #
Component
1
Movable Plate 2
7
Insulation Strip
2
Movable Plate 1
8
Stoker Bar
3
Screw, #10-24 x ½” Long
9
Threaded Rod, ¼”
4
Screw, #6-32 x 1.00” Long
10
Cap Nut, ¼”
5
Nylon Screw, #10-24 x ½” Long
11
WHITE Coal Feed Adjustment
6
Nylon Screw, #10-24 x ¾” Long
12
Nut, ¼”
WHITE COAL FEED ADJUSTMENT (ITEM # 11): Turn clockwise for more coal feed, turn
counterclockwise for less coal feed.
NYLON ADJUSTING SCREWS (ITEM #’s 5 &6): To eliminate metal on metal contact. There
are 8 nylon screws on the pusher bar, 4 on each side. The 4 nylon screws pictured on
diagram are used to adjust the amount of sideward movement of pusher bar. When
FIGURE 3

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 12 -
nylon screws are properly aligned, the pusher bar will slide in and out freely and have
only a slight sideward movement.
NYLON CAM: located on gear motor. To give
reciprocating motion to pusher bar shown below.
GEAR MOTOR: The drive shaft turns approximately
1RPM. The nylon cam on drive shaft will, when moving
inward, force coal from hopper onto grate. When
withdrawing, will allow coal to fall in front of pusher bar
for preparation of next inward stroke. The gear motor
will only run when activated by a call for heat from
thermostat or when timer turns it on.
AIR INTAKE ADJUSTMENT SHUTTER: Adjusts amount of air flow through fire.
COMBUSTION MOTOR: Combustion motor will run all the time to force air through holes
in grate to burn coal. The constant running of motor will assure the maximum amount of
heat is gained and will aid in a more complete burning of coal. The motor has an
adjustable air shutter for regulating air flow through fire.
Nylon Cam
Gear Motor
Adjustment Shutter
Adjustment Screw
Fan
FIGURE 4
FIGURE 5
FIGURE 6
Oil Ports

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 13 -
TIMER: Unless your stove had been a special order, it will be equipped with our
patented flat grate stoker unit and a timer. The purpose of a timer is to maintain a
minimum fire when the thermostat is not calling for heat.
Timer Switch Examples
Times can be adjusted by moving the switch next to the number.
ON TIME
SWITCHES
TURNED ON
OFF TIME
SWITCHES
TUNED ON
Average Boiler and
Warm Air furnace
Idle Time Examples
34 seconds on #6, #2 10 minutes off #4, #2
40 seconds on #6, #4 10 minutes off #4, #2
45 seconds on #6, #4, #3, #1 10 minutes off #4, #2
Older boiler and
Warm Air Furnace
idle time without
secondary blower
Examples
1 min on #6, #5, #4, #3 10 minutes off #4, #2
1 min 15 sec on #7, #4, #2, #1 10 minutes off #4, #2
1 min 30 sec on #7, #5, #4, #2 15 Minutes Off #4, #3, #2, #1
ON TIME
SWITCHES
TURNED ON
OFF TIME
SWITCHES
TUNED ON
Average Stove with
combustion fan
running constantly
1 min 15 sec on #7, #4, #2, #1 10 minutes off #4, #2
1 min 30 sec on #7, #5, #4, #2 15 minutes Off #4, #3, #2, #1
Average older stove
without combustion
fan running
constantly
1 min 15 sec on #7, #4, #2, #1 10 minutes off #4, #2
1 min 30 sec on #7, #5, #4, #2 10 minutes Off #4, #2
Refer to pages 21 - 24 for wiring diagrams.
Light will be red when N.O. is powered. Sending power to
feeder motor.
Light will be green when N.C. is powered. Not sending power to
feeder motor.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 14 -
THERMOSTAT:Top pointer is to be set at warmth
desired in home. Bottom pointer is the present
temperature in room. When room temperature
(bottom pointer) falls below desired room
temperature, (top pointer), this will send a signal to
the Relay control to activate gear motor to push fresh
coal onto grate
FAN LIMIT SWITCH:
1. HIGH LIMIT POINTER-is a safety switch that
stops gear motor from pushing coal onto
grate at 200 degrees (If stove gets too hot,
this switch will turn off gear motor).
2. CENTER POINTER-turns convection blower
on when internal air temperature reaches this
setting (normally set around 160 degrees, but
is adjustable).
3. LOW POINTER-turns convection blower off
when internal air temperature falls to this
setting (normally set around 120 degrees, but
is adjustable).
4. Whatever number on silver dial is directly
above this point is temperature of internal air.
5. WHITE BUTTON-pull out for automatic
operation of convection blower. Push in for
constant running of convection blower.
6. On this application, the JUMPER PIN is left
intact
RELAY: Receives signal from 24V thermostat to turn on or turn off gear motor.
CONVECTION BLOWER: When running, it will take cool air from room, and force it
through heated air chamber inside stove, and return heated air into room. Blower can
only be activated by Fan Limit Switch.
Load
Fan
Line
Load
Fan
Line
Load
Limit
Line
Break Off
Jumper for
Low Voltage
4
5
1
2
3
FIGURE 8
FIGURE 9

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 15 -
Maintenance
Cleaning & Lubrication of Stove
Stove pipe and exhaust tubes must be cleaned once during the heating season. On
top exhaust stoves, brush exhaust tubes out with a flexible brush. Keep base and interior
openings below interior exhaust tubes clear of ash. Clean under grates annually by
removing combustion motor and vacuuming under grates or you may remove the bolt
holding the grates and then remove the grate and proceed to vacuum. Grates must
then be re-cemented back into their place. Upper portion of grates must be sealed (air
tight) with furnace cement, from the upper portion of the grate (close to hopper) down
to where the 1/8” holes are drilled in grates.
Lubricate combustion motor and convection fan motor with a light grade of regular
motor oil.
Oil fire door and ash door hinges. Oil threads on fire door and ash door handles to
prevent freeze up over summer.
To minimize corrosion of stove accessories, it is important to clean stove thoroughly at
the end of heating season. Completely remove all coal from hopper. Remove and
clean stove pipe. Check chimney and base of chimney for obstructions or blockage.
Clean under grate.
Cleaning Stove Glass (not available with all models)
The following instructions are meant to serve as guidelines for proper cleaning and care
of ROBAX glass ceramic windows.
To clean glass, first turn down the thermostat to allow the stove to cool.
ALL cleaning procedures should be done at room temperature CLEANING OF HOT
GLASS SHOULD BE AVOIDED. Cleaning solutions applied to hot glass may dry before
cleaning agent is removed, which may result in creating a film or deposit that can
react with combustion by products. Dried on cleaning solution may react with surface
causing discoloration or a permanent film.
If white deposits are found to be on the surface of glass, these should be scraped off
using a sharp bladed scrapper and wiped away with a dry cloth prior to any wet
cleaning. Scrapping should be done at a low angle below 30 degrees.
Although glass is extremely hard and very scratch resistant, it is not scratch proof. The
use of abrasive cleaners (i.e., any cleaners containing grit) and scouring pads (i.e., steel
wool, plastic with embedded grit) should be strictly avoided.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 16 -
Soft cloths should be used for all cleaning steps. The cloths should be free of any
abrasive agents from any previous use.
Dried on cleaning solutions may react with glass surface causing discoloration or a
permanent film.
While ROBAX glass is the best glass for use on anthracite burning coal stove, the
manufacturer does not warranty the glass.
Ash Pan Emptying
To prevent toxic carbon monoxide gases from entering the home, certain precautions
must be taken.
1. Ash pan must be emptied on a regular basis to prevent ashes from overflowing
into ash pit area. Excessive ash accumulation may impede air flow to chimney,
preventing gases to be drawn up chimney.
2. Fire door and ash door must be kept closed at all times during normal operation.
3. It is necessary to keep coal in hopper while stove is in operation.
4. In most applications it is sufficient to clean stove and stove pipe twice during
heating season. However, under extreme weather conditions, or high demand
on stove running periods, the stove and stove pipe may need more frequent
cleaning. Clean as often as necessary.
CAUTION: ASH PAN IS HOT-Always Use Gloves to Remove Ash Pan
1. Before removing ash pan, turn switch off, or pull power cord plug from 110V
outlet.
2. Open ash door.
3. Use a good pair of gloves, to remove ash pan.
4. Place filled ash pan on a non-combustible surface.
5. Slide an empty ash pan into stove.
6. Close ash door.
7. Turn switch on or plug power cord back into 110V outlet.
For Direct Vent Stoves
Fan blade and fan blade chamber may have to be cleaned several times during
heating season. (See Cleaning instructions)
The 4” exhaust pipe going through outside wall of home should also be cleaned when
fan chamber is being cleaned.
If 4” exhaust pipe is not going straight out through outside wall and 4” pipe is in a
vertical position to access an area above outside grade, the 4” elbow is a common
location for dust to accumulate and restrict exhaust air flow to outside of home. A 4”
tee may also be used in place of a 4” elbow. This will allow the bottom of tee to be
used as a collection point (out of the flow of exhaust gases) providing an easier access
for cleaning and less chance for restriction or blockage.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 17 -
It is ESSENTIAL…that every 4” pipe joint or connection be sealed with a high
temperature silicone or equivalent. All adjustable joints on elbow must also be sealed
with silicone. FAILURE TO SEAL ALL JOINTS could allow carbon monoxide to leak into
home.
Gear Motor Removal & Installation
Refer to the following Figures 10 & 11
TO REMOVE GEAR MOTOR:
1. Pull power cord plug from 110V outlet.
2. Remove #10-24 machine screw and then remove protective cage.
3. Disconnect both blue wire nuts marked.
4. Remove both #10-24 machine screws from mounting bracket.
5. Slide gear motor out of its track toward you, pusher bar will also come out with
gear motor.
6. While pusher bar is out of its chute, clean chute area and remove any
obstructions. Check nylon screws on pusher bar (4 on each side) for wear or
breakage. (Replace if necessary)
7. Slide pusher bar in and out of chute (should move freely) check for sideward
movement.
8. Adjust nylon screws on right side to allow only a slight sideward movement.
TO REPLACE GEAR MOTOR:
1. Remove (4) 10-32 machine screws that hold gear motor onto mounting bracket.
a. Before removing gear motor from bracket, look at position of gear motor;
install new motor in exact same position before reinstalling screws.
2. Reverse removal procedure and reinstall.
3. When replacing gear motor with a new one, both gear motor wires are black; either
wire may go to red or white wire from power supply.
Nylon Cam
Spring Pin
1/8” x 1-1/4” Long
Screw
#10-32 x ¾” Long
Rubber Grommet
Screw
#10-24 x ½” Long
Screw
#10-24 x ½” Long
Gear Motor
Fan
FIGURE 10

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 18 -
Fan
Screw
for
Cage
FIGURE 11
Screw
#10-24 x ½” Long
Bottom of Stoker Unit
Gear Motor
Support
Brackets

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 19 -
Troubleshooting Guide
Problem
Fix
FIRE GOES OUT
See page 13 (Timer) and Page 9 Diagram 2
COAL KLINKERING OR FUSING
TOGETHER
See pages 8 & 9 Diagram 1 & 2
SULFUR SMELL
See page 15 (Cleaning & Lubrication and Check
Draft section, Page 7)
STOKER UNIT DOESN’T FEED
COAL
See page 11 (Pusher Bar)
PUSHER BAR IS NOT MOVING
STRAIGHT
See page 11 (Pusher Bar)
CONVECTION BLOWER RUNS
TOO OFTEN
See page 14
CONVECTION BLOWER RUNS
CONSTANTLY
Pull white button on Fan Limit Switch out for
automatic operation. Clean screen and fan blades
on blower. See page 14
THERMOSTAT CALLS FOR
HEAT, but CONVECTION
BLOWER OFF TOO LONG
See Page 14 Diagram 1
FIRE IS LIT, BUT NOT ENOUGH
HEAT
If gear motor only runs short cycles, timer is working.
When thermostat calls for heat, gear motor should
run steady. If gear motor is running steady, but fire is
small, increase coal feed. See pages 8, 9 & 11
If gear motor is not running steady, check for loose
wire in Thermostat or in Relay. Check for broken
thermostat wire between thermostat and Relay.
GEAR MOTOR RUNS
CONSTANTLY MAKING TOO
MUCH HEAT
1. Gear motor can only be activated by thermostat
or timer.
2. Remove thermostat wires from T.T. terminals in
Relay, if gear motor shuts off, replace thermostat
wire or Thermostat.
3. OLDER MODELS: Check timer to see if yellow
wheel is turning, if not replace timer motor.
4. Check timer switch. See page 13 and Fig. 7 Timer
CONVECTION BLOWER NOT
BLOWING MUCH AIR
Clean screen and fan blades on blower.
GEAR MOTOR SHUTS OFF ON
HI-LIMIT
High Limit pointer in Fan Limit Switch is designated to
shut gear motor off when internal air temperature
reaches 200 degrees. If internal air temperature stays
on 200 degrees, Convection Blower is not cooling
stove off quickly enough. Clean screen and fan
blades on blower or replace convection blower or
See Page 14, Fan Limit Switch.

Keystoker – Schuylkill Haven, PA 17972 Koker, Koker Lite & Econo 90 Stoker Coal Stoves
© June 2019 REV 4 - 20 -
Troubleshooting Guide – cont’d
Problem
Fix
BIG FIRE BUT NOT MUCH HEAT
Fan blades on combustion motor dirty. Brush off.
Accumulated fly ash under grate. Remove
combustion motor and clean under grate.
Holes blocked in grate. Open holes with 1/8” center
punch. See Page 10 Figure 2
TO CLEAN UNDER OR REPLACE GRATE See Page 15
(Cleaning & Lubrication) & Page 10 Figure 2
NYLON CAM MELTS
Under normal operating conditions, nylon cam will
not melt. Melting of nylon cam can only be caused
by a draft problem.
A blockage in chimney, chimney connector, stove
pipe, or stove. Inspect and clean.
Or excessive draft, caused by high chimney, large
flue, or high winds. Clean and adjust barometric
damper. (Set barometric damper with a draft gauge
to obtain a draft reading of -.02 to -.03, See Page 7
Check Draft)