USSC 6220 keeps shutting down.

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
I have a 6220 pellet furnace and suddenly it keeps shutting down with an error code 2. Strangely the fire seems to be going strong when it does this. Pellets are feeding fine, vacuum seems fine and the fire is hot. Stove feels like its up to operating temp to me but the room fan only comes on in short bursts a few times, then it shuts down and I get error code 2. My gut feeling is a thermostat is bad and not telling it that its reached operating temp but thats just a guess. Error 2 also list "electrical open in low temperature switch or wiring". What exactly does this mean? Where is the low temperature switch?
 

johneh

Minister of Fire
Dec 19, 2009
2,351
Eastern Ontario
Welcome to the forum
Code 2
Error list
 Hopper Empty  Auger Output Failure or Jam  Flame or Fuel Quality Caused Fire to burn to slowly or go out  Electrical Open in Wiring  Vacuum pressure issue
I take it the hopper has pellets?
If there is fire and a good flame the auger works
Flame quality? (hot, cold ?)
Electrical open (burnt, disconnected wire, loose wire or plug, connections corroded
Vac switch Hose or nipple plugged (blow it out from the switch end)
door seal, ash pan seal OK (Dollar bill test)
Jump wires at vac switch and do a test burn
If it now works properly replace vac switch
Good Luck
 

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
Welcome to the forum
Code 2
Error list
 Hopper Empty  Auger Output Failure or Jam  Flame or Fuel Quality Caused Fire to burn to slowly or go out  Electrical Open in Wiring  Vacuum pressure issue
I take it the hopper has pellets?
If there is fire and a good flame the auger works
Flame quality? (hot, cold ?)
Electrical open (burnt, disconnected wire, loose wire or plug, connections corroded
Vac switch Hose or nipple plugged (blow it out from the switch end)
door seal, ash pan seal OK (Dollar bill test)
Jump wires at vac switch and do a test burn
If it now works properly replace vac switch
Good Luck
Did as you said and got to the point of the vacuum switch. I blew the hose out as well and that seemed fine. Jumped the wires and it did run for a 1/2 hour seemingly ok and then error 2 again but this time seemed to run out of pellets for some reason.
Assuming it is the vacuum switch, what is the difference between 80549 and 80514 besides the $130 price jump? Why are all pellet stove parts so far out of line in price? Most mp2168 switches are in the $20 to $35 range. but for pellet stoves they jump to $150 to $200 range.
 

johneh

Minister of Fire
Dec 19, 2009
2,351
Eastern Ontario
Did you run out of pellets or did the auger stopped working
Time frame Was the fire a good hot strong flame (Pos proof of fire)
Low limit switch Stove not reaching min. operating temp
The company's that sell parts like to make a chit load of money
on each part
 

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
Did you run out of pellets or did the auger stopped working
Time frame Was the fire a good hot strong flame (Pos proof of fire)
Low limit switch Stove not reaching min. operating temp
The company's that sell parts like to make a chit load of money
on each part
Yes the fire looked like a good hot fire. plenum was very hot to touch. hopper was full and pellets were feeding. I walked away for a bit and when I came back it was out again with error 2. Where is the low limit switch located?
 

johneh

Minister of Fire
Dec 19, 2009
2,351
Eastern Ontario
Did the fan come on to blow the hot air Convection fan?
The unit may have overheated. Check the Hi-Limit switch may have a red reset button on it
If the convection fan did not come on, test to see that it works
 

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
Did the fan come on to blow the hot air Convection fan?
The unit may have overheated. Check the Hi-Limit switch may have a red reset button on it
If the convection fan did not come on, test to see that it works
yes the room fan came on and was running steady when I left. where is the high limit switch located?
 

johneh

Minister of Fire
Dec 19, 2009
2,351
Eastern Ontario
Iflyrctoo
I am at the end of my knowledge of your furnace have not worked on one
in a long time. Hopefully, someone will jump in at this point and help
 

ARC

New Member
Oct 31, 2017
47
Au Sable Forks, NY
To test the vacuum switch turn it off using the c codes.

To adjust the operation constant, press and hold the MODE and AUGER DELAY buttons
simultaneously for 3 seconds. The display will show “C-1”. Use the HEAT RANGE UP or HEAT
RANGE DOWN buttons to change the constant number (see the list of values below). When the
desired constant is displayed, press the ON button to toggle between viewing and editing the value.
While editing a parameter, use the AUX UP and AUX DOWN buttons to adjust the values to the
desired point, then press ON again to return to the constant number list. Press the OFF button to
exit the adjust operational constants mode.
C-20- Ignore Vacuum Switch (0-1)- When this parameter is set to 1, the vacuum switch is
ignored. The default is 0 (do not ignore the vacuum switch). Note only turn this off if you will be around to watch stove.

I do not have the stove but I do not believe it has a high or low limit switch. High and low limits are based on Thermistor attached to exhaust which tells the control board the temp. Should be plugged into your control board and the other end should be bolted around exhaust motor housing. Check to see if it is plugged in tightly and bolted snugly.
thermistor.jpg
 
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Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
To test the vacuum switch turn it off using the c codes.

To adjust the operation constant, press and hold the MODE and AUGER DELAY buttons
simultaneously for 3 seconds. The display will show “C-1”. Use the HEAT RANGE UP or HEAT
RANGE DOWN buttons to change the constant number (see the list of values below). When the
desired constant is displayed, press the ON button to toggle between viewing and editing the value.
While editing a parameter, use the AUX UP and AUX DOWN buttons to adjust the values to the
desired point, then press ON again to return to the constant number list. Press the OFF button to
exit the adjust operational constants mode.
C-20- Ignore Vacuum Switch (0-1)- When this parameter is set to 1, the vacuum switch is
ignored. The default is 0 (do not ignore the vacuum switch). Note only turn this off if you will be around to watch stove.

I do not have the stove but I do not believe it has a high or low limit switch. High and low limits are based on Thermistor attached to exhaust which tells the control board the temp. Should be plugged into your control board and the other end should be bolted around exhaust motor housing. Check to see if it is plugged in tightly and bolted snugly.
View attachment 250902
There are two Thermistors, one on the exhaust as you describe and one in the plenum. My original thought was it might be one of those but didnt know if there were other thermal switches somewhere. They are both plugged in and appear intact.

Im leaning more now to the vacuum switch. I removed it last night and tried testing it for continuity while applying vacuum to the one side. initially there was no change but eventually it seemed to start working the more I played with it. I reinstalled it, cleaned the entire furnace and pipes and started it up again. It ran for at least a few hours but when I awoke this morning it was again out with error 2. Maybe the switch is sticking . I will try the test you suggest tonight and then see about ordering a new switch. Do you know if the USSC 80549 switch is compatible with the 6220 stove? It calls for the 80514 switch but the only version I can find of that is about 5 times the price. one is .04WC the other .05WC Seems like a minuscule difference in vacuum to me.
 

ARC

New Member
Oct 31, 2017
47
Au Sable Forks, NY
Jumped the wires and it did run for a 1/2 hour seemingly ok and then error 2
You wrote that you jumped the vacuum wires and it still gave error 2, how did you jump wires did you use a double male spade jumper or did you just rig something up? If you are sure you jumped wires correctly then problem is not switch but could be a Electrical Open in Wiring (short). Inspect wires from the vacuum switch to the control board for any kinks, pinches, bare wires , stretched wire or bad spade connections. If you turn the vacuum switch off with the C 20 and run the stove that will let you know if the problem is in the vacuum side of the stove or someplace else

male spaded jumper wire.jpg
 

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
You wrote that you jumped the vacuum wires and it still gave error 2, how did you jump wires did you use a double male spade jumper or did you just rig something up? If you are sure you jumped wires correctly then problem is not switch but could be a Electrical Open in Wiring (short). Inspect wires from the vacuum switch to the control board for any kinks, pinches, bare wires , stretched wire or bad spade connections. If you turn the vacuum switch off with the C 20 and run the stove that will let you know if the problem is in the vacuum side of the stove or someplace else

View attachment 250924
I pulled one spade off the switch and the opposite one off the board & used that wire as a loop between the two board connections for the switch. Wires & connectors appear tight & fine. It did run for a half hour or more that way before shutting down error 2. Pot was pretty well burnt out of pellets this time for some reason.
Last night I removed & reinstalled the switch as originally installed after fooling with it and it ran for several hours before shutting down. I also did a board reset to defaults before starting it up. It was cold out last night and It ran ok for a least a few hours but was out with error 2 again this morning. Pot still had some pellets in it.
Nothing seems logical to me in the way its acting.
 

Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
I pulled one spade off the switch and the opposite one off the board & used that wire as a loop between the two board connections for the switch. Wires & connectors appear tight & fine. It did run for a half hour or more that way before shutting down error 2. Pot was pretty well burnt out of pellets this time for some reason.
Last night I removed & reinstalled the switch as originally installed after fooling with it and it ran for several hours before shutting down. I also did a board reset to defaults before starting it up. It was cold out last night and It ran ok for a least a few hours but was out with error 2 again this morning. Pot still had some pellets in it.
Nothing seems logical to me in the way its acting.
I tried it out again last night after cleaning out the hopper to make sure no accumilation of sawdust or any thing was interfering with pellet flow. (it wasnt bad). After that it again ran fine for about 3 hours. I checked it then and all looked well. Fire looked normal, pellets were feeding fine, fans were all running normally. Then 20 minutes later it was shut down with error 2 and there was still a bed of glowing coals in the firebox. So it did not just run out of fuel. I have not tried ignoring the vaccum switch yet with the C-codes. But you are right in that when I jumped the switch with the wire and tried it, it still shut down error 2. Sounds more like a thermsistor again then doesnt it. Is there a way to test each of those to be sure?
 

ARC

New Member
Oct 31, 2017
47
Au Sable Forks, NY
Pay attention to number 9 and 10 will show if Thermistors are working. Also check C11 and C12.

6220 4 Digit Board Test
To run this test the UNIT MUST BE COOLED OFF. Power up the unit by plugging in the power
supply cord to the back of the unit. Press the on button and the circuit board then press and hold
the Off and Auger Delay buttons simultaneously for 3 seconds. To advance through the test
press the on key.
1. Exhaust Fan Output Test- The display will show “drift”. The exhaust fan is turned on full then
reduced to a level just above the typical minimum pressure switch setting. The ON LED indicates
whether the pressure sensor is detected. If the pressure switch is not detected, the fan ramps to full
on for two seconds then returns to the previously established level if the pressure switch closes. If
the Draft Fan Fuse is not blown and the fuse detection circuit is functioning, the Draft Fan LED will
be lit and the other three top row LEDs will be off.
2. Room Fan 1 Output Test – The display will show “rfn1”. The room fan 1 is turned on full. If the
Room Fan 1 Fuse is not blown and the fuse detection circuit is functioning, the Room Fan LED will
be lit and the other three top row LEDs will be off.
3. Room Fan 2 Output Test- The display will show “rfn2”. The room fan 2 is turned on full. Since
there is no blown fuse detection circuit on the daughter board fan, none of the top row LED’s should
be lit.
4. Agitator Output Test- The display will shows “agit” The agitator is turned on full. If the Agitator
fuse is not blown and the fuse detection circuit is functioning, the AUX LED will be lit and the other
three row LED’s will be off.
5. Auger Output Test – The display will show “augr”. If the Hopper switch is open( lid open) the ON
LED will turn on otherwise, it will be OFF fuse.
6. Hopper Switch Test – The display will show “Hppr”. The igniter motor is turned on full. If the
Igniter (AUX) Fuse is not blown and the fuse detection circuit is functioning, the AUX LED will lit
and the other three top row LEDs will be off.
7. Thermostat Input Test – The display will show “stat”. If the thermostat input is closed, the ON
LED light will be on, otherwise it will be off.
8. Interlock Switch Test – The display will show “intl”. If the interlock is made (closed), the On LED
will turn on otherwise, it will be off.
9. Flue gas Thermistor Test – The display will show the flue gas temperature in degrees F.
10. Vent Thermistor Test- The display will show the vent temperature in degrees F.
11. Ambient Thermistor Test- The display will show the temperature of the daughter board
thermistor in degrees F.
12. AC Frequency Test - Displays the measured AC frequency in hertz followed by the letter “H”.
This should read 59, 60, or 61H
13. Watchdog Reset – The Watchdog timer is tested to ensure that the board can be reset. The
message “BYE” will be displayed until the Watchdog resets board.

C-11- Overtemp Setpoint-(0-400) - This is the measured flue gas temperature that will
cause an overtemp condition. In this condition, the control will stop auguring fuel until the
temperature returns to a safe operation point. The default is 325°F.
C-12- Cutback Setpoint-(0-400) - This is the measured Flue gas temperature that will cause
an overtemp condition. In this condition, the control will ramp the heat range down based
on the ramp seconds described above divided by 2 until the temperature falls below the
cutback setpoint. The default is 300°F.
 

ARC

New Member
Oct 31, 2017
47
Au Sable Forks, NY
Sounds more like a thermsistor again then doesnt it.
Might be weak or failing auger motor, check your hair pin and make sure it is not busted. Auger motor might be failing/heating up and stopping after 3 hours of use. Then after it cools down it can be started back up. Auger might be binding in the brass bushing. Would be nice to know if it is getting the err 2 message then stopping pellets/auger or if pellets/auger stops then the err 2 but sitting and watching the furnace for 3 plus hours is not entertaining. Check how hot the auger motor is if you get to stove soon after it shuts down.
 
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Iflyrctoo

New Member
Nov 7, 2019
9
Central NY
Pay attention to number 9 and 10 will show if Thermistors are working. Also check C11 and C12.

6220 4 Digit Board Test
To run this test the UNIT MUST BE COOLED OFF. Power up the unit by plugging in the power
supply cord to the back of the unit. Press the on button and the circuit board then press and hold
the Off and Auger Delay buttons simultaneously for 3 seconds. To advance through the test
press the on key.
1. Exhaust Fan Output Test- The display will show “drift”. The exhaust fan is turned on full then
reduced to a level just above the typical minimum pressure switch setting. The ON LED indicates
whether the pressure sensor is detected. If the pressure switch is not detected, the fan ramps to full
on for two seconds then returns to the previously established level if the pressure switch closes. If
the Draft Fan Fuse is not blown and the fuse detection circuit is functioning, the Draft Fan LED will
be lit and the other three top row LEDs will be off.
2. Room Fan 1 Output Test – The display will show “rfn1”. The room fan 1 is turned on full. If the
Room Fan 1 Fuse is not blown and the fuse detection circuit is functioning, the Room Fan LED will
be lit and the other three top row LEDs will be off.
3. Room Fan 2 Output Test- The display will show “rfn2”. The room fan 2 is turned on full. Since
there is no blown fuse detection circuit on the daughter board fan, none of the top row LED’s should
be lit.
4. Agitator Output Test- The display will shows “agit” The agitator is turned on full. If the Agitator
fuse is not blown and the fuse detection circuit is functioning, the AUX LED will be lit and the other
three row LED’s will be off.
5. Auger Output Test – The display will show “augr”. If the Hopper switch is open( lid open) the ON
LED will turn on otherwise, it will be OFF fuse.
6. Hopper Switch Test – The display will show “Hppr”. The igniter motor is turned on full. If the
Igniter (AUX) Fuse is not blown and the fuse detection circuit is functioning, the AUX LED will lit
and the other three top row LEDs will be off.
7. Thermostat Input Test – The display will show “stat”. If the thermostat input is closed, the ON
LED light will be on, otherwise it will be off.
8. Interlock Switch Test – The display will show “intl”. If the interlock is made (closed), the On LED
will turn on otherwise, it will be off.
9. Flue gas Thermistor Test – The display will show the flue gas temperature in degrees F.
10. Vent Thermistor Test- The display will show the vent temperature in degrees F.
11. Ambient Thermistor Test- The display will show the temperature of the daughter board
thermistor in degrees F.
12. AC Frequency Test - Displays the measured AC frequency in hertz followed by the letter “H”.
This should read 59, 60, or 61H
13. Watchdog Reset – The Watchdog timer is tested to ensure that the board can be reset. The
message “BYE” will be displayed until the Watchdog resets board.

C-11- Overtemp Setpoint-(0-400) - This is the measured flue gas temperature that will
cause an overtemp condition. In this condition, the control will stop auguring fuel until the
temperature returns to a safe operation point. The default is 325°F.
C-12- Cutback Setpoint-(0-400) - This is the measured Flue gas temperature that will cause
an overtemp condition. In this condition, the control will ramp the heat range down based
on the ramp seconds described above divided by 2 until the temperature falls below the
cutback setpoint. The default is 300°F.
OK we MAY be getting somewhere now. Think we pretty much eliminated the vacuum switch as the culprit. I ran it this afternoon with the ignore option for the vacuum and it still shut down after about 40 minutes with error 2.

I also ran the above test as you described right when it shut down.
#9 was 154F (is this the one on the draft exhaust fan?)
# 10 was 7F (yes thats seven degrees) (is this the one in the plenum???)( sounds bad to me!!!!)(sure as hell nothing there was 7 degrees)
# 11 was 84F (where exactly is this one located? somewhere on the actual motherboard?)
#12 didnt seem to exist, it goes from 11 to BYE

but then I let it cool down for 2 hours and ran them again. This is where I really get confused.
#9 was now 54F (exactly 100 degrees lower)
#10 was 54F ( now exactly the same as #9)
# 11 was was 184F (exactly 100 degrees higher )( It sure wasnt 184 degrees anywhere in the basement)

So then on a whim I reversed the two thermistors as to where they were plugged into the mother board and ran the test again.

I got exactly the same results as above.

So then I decided to start it up again with the two thermistors still plugged into the opposite ports on the board. Its currently still running like this and its been almost 3 hours.

So given all this. what do you think now??? If i hadnt done the test after it cooled down, I would say #10 (wherever that one is located) was the culprit. But can you make any sense of the 2nd and 3rd tests?
 

ARC

New Member
Oct 31, 2017
47
Au Sable Forks, NY
Not sure what to make of your first test numbers as the test is only meant to be done on a cold stove so not sure what the numbers mean if anything. If it read only 7 when running it should have given a err 4 code "low limit".

Switching the thermistors input plugs is going to confuse the control board programing, it will think plenum is to hot and ramp up blowers and ramp down heat but at the same time it will read exhaust is to cool and try to ramp down blowers and ramp up heat.

On the second test after the unit cooled down the numbers for the two thermistors appears to be what you would expect. The number for the mother board is way to high. I would suspect the transformer or the triac that controls the auger is overheating. Not sure if triac is overheating , causing the auger to stop or if the auger is failing, causing the triac to overheat. It should blow the auger fuse but sometimes it just doesn't happen.

The best way to check the auger is to be standing there when it happens, you should be able to hear a hum as the auger tries to turn and doesn't. It could be the auger motor, the gear box that is attatched to the motor or something binding the auger itself. You can also take the auger motor/gearbox off stove and bench test it with a old lamp cord but sometimes they will bench test O.K. as it might need the load of pushing pellets to fail.
 
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