P68 won't shut down when turned off...keeps 'bumping' auger every 60sec

[Pkcal]

Searched and haven't found a similar problem so here goes. 5yr old P68, been running fine burning 3tons/yr or so then started acting up this year. Starts and runs great in Room or Stove temp mode, problem is when we shut it down by turning the Fan selector to Off, it acts like it wants to shut down (Status light goes out, distribution blower shuts off) but every 60sec it bumps the auger for 1-2seconds, continuing to slowly feed a small amount of pellets into the burnpot and as a result, keeps burning and won't shut down. The only solution I've found to get it to shut down completely is to open the hopper for a few minutes to 'break the cycle' of the autofeed keeping the stove running. Couple times even doing this it came back to life and was back burning when I got up in the AM.

My understanding is the 'bump' every 60sec or so is part of the normal shutdown and is intended to prevent fire from backing up into the hopper......until the ESP drops to a low enough temp that the stove is confident the fire is too low to burn back into the hopper.

Cleaned stove thoroughly, cleaned ESP thoroughly and no change. Replaced the ESP this weekend and still does the same thing.

Thoughts? Thanks in advance for the help.

 

[rayttt]

Have you cleaned the Fines Box out?

 

[subsailor]

How long have you waited? My P-61 has fed pellets for over a half hour after turning it off when it was burning at a high temp.

 

[Pkcal]

Thx for the replies.

Yes if the fines box is accessed in the rt rear when looking at the stove from the front (remove single wingnut and vertical plate next to hopper/auger and vacuum out). That has been cleaned out within the past month.

Re: waiting, I've left it for 4+ hrs and come home to it just sitting in slow burn mode bumping the auger a turn or so every 60sec or so.

 

[rayttt]

The Potentiometer could be dirty...easy to see...
You can just take the Stove mode dial and swirl it back and forth from end to end a couple of dozen times.
hows the indent feel?
if absolutely nothing changes..then others with the P68 (I have P38) might be better able to help.
Hows the vacuum line?

 

[newf lover]

Same thing happened to me and it was the control board.

 

[smwilliamson]

Control board baby!

 

[David E Girard Sr]

Mine Was Control Board Same Symtoms,, I Also Have A P61-2 That Won't Go To Low Burn, Will Burn1.5 On Lowest Settings, Just Converted It To Autolite New Control Board , New Red Esp, No Change,, Any Ideas?? Should Burn .75 On Lowest Settings, At Least It Used To Do That,,,,

 

[mikesj]

Did your dealer tell you about the esp wires? If your old one had black wires and the replacement has red wires you might have to adjust a dip switch.

 

[David E Girard Sr]

Did your dealer tell you about the esp wires? If your old one had black wires and the replacement has red wires you might have to adjust a dip switch.

Yes Did That , Have Been So Far Succesfull Doing My Own Repairs For 6 Or So Years Now, Acting The Same As It Did With All The Old Equipment, Just Won;t Go Down To .75 Lbs Per Hour??? Burns At About 1.5lbs On Lowest Setting , I Am Stumped???

 

[SmokeyTheBear]

Yes Did That , Have Been So Far Succesfull Doing My Own Repairs For 6 Or So Years Now, Acting The Same As It Did With All The Old Equipment, Just Won;t Go Down To .75 Lbs Per Hour??? Burns At About 1.5lbs On Lowest Setting , I Am Stumped???

Is your board set for the stove it is in? Has your auger motor ever been replaced?

There are two settings for the p68 depending upon the auger motor being 4 or 6 RPM.

Please see: http://www.google.com/imgres?imgurl...&sa=X&ei=dJGgUpqTM8yNkAf43IEw&ved=0CGMQ9QEwCQ

 

[smwilliamson]

forget the feed rate issue, well call that issue #2...issue #1 is that it is not shutting off, that will be a control board OR there may be a chance that the igniter is wired to the wrong output...but that would involve cutting wires and replacing connections, if you havent done that, then you need a new control board.

 

[SmokeyTheBear]

If the controller is looking for temperature x and the esp selection is incorrect or the bump to prevent issues during shutdown is too big the proper temperature may never be seen.

Just adding another set of options to the list of possible causes.

 

[Pkcal]

I'm on Issue #1 - won't shut down and have just ordered the Control Board from my local dealer for $188. Thanks for the help. Given I'm not changing anything else, my assumption is I will set the DIP switches on the new board to match the old board then all should be good to go?

Once installed I'll confirm that fixed the issue to close out the thread for future searches.

 

[David E Girard Sr]

Hello, Again Smokey, Let Me Start Over, I Have A P 61-2 , It Was Not Autolite, And Would Not Turn Down To .75 Lbs Per Hour, Has Been Like This For About A Season, I Thought It Was The Control Board, So I Went And Converted It To A Autolite New Control Board, New Esp Sensor, Red, Control Board Is Set To Factory Sheet, #5 Switch Is In The Correct Position, Stove Runs And Heats Fine, Until I Put It In Stove Temp Overnight, lowest Settiing And Burn A Bag In 12 hours, So About A 1.5 lBS A Hour, Air Setiing Correct, Gaskets Good, Still Has The Original 4 Rpm Auger Motor, I Am Baffled As To What This Could Be???? I Do Need It To Throtlle All The Way Down,,,,,,,Ideas?? Harman Dealer Doesn't Seem To Know,

 

[SmokeyTheBear]

Hello, Again Smokey, Let Me Start Over, I Have A P 61-2 , It Was Not Autolite, And Would Not Turn Down To .75 Lbs Per Hour, Has Been Like This For About A Season, I Thought It Was The Control Board, So I Went And Converted It To A Autolite New Control Board, New Esp Sensor, Red, Control Board Is Set To Factory Sheet, #5 Switch Is In The Correct Position, Stove Runs And Heats Fine, Until I Put It In Stove Temp Overnight, lowest Settiing And Burn A Bag In 12 hours, So About A 1.5 lBS A Hour, Air Setiing Correct, Gaskets Good, Still Has The Original 4 Rpm Auger Motor, I Am Baffled As To What This Could Be???? I Do Need It To Throtlle All The Way Down,,,,,,,Ideas?? Harman Dealer Doesn't Seem To Know,

Has your dealer attached his diagnostic tool to the stove to verify that the dip switches are being seen as you have them set?

Dip switches are funny things they don't always make a connection (like any switch they get stuck or dirty or don't get fully moved to the proper end of their range), or have cold solder joints that fail over time due to temperature changes vibration etc ...

When one operates large numbers of devices with several dip switches in each device they frequently wish the switches were for jumpers or wire wrap.

Don't get me started on pots on control boards that find their time mostly at one setting.

I've also seen them set in reverse order due to being mislabeled on a pc board (sticker on in the wrong direction)

 

[David E Girard Sr]

Well, It Is A New Control Board, I Did Set The Switches Firmly, So I Guess Its Time To Spend Money On The Harman Man,, Or I Could Buy The Diagnostic Tool Myself ,, Saw One New, Online For Sale, Thank You, PS , My P68 Is In My Basement, So That Makes Me A Basement Dweller??

 

[SmokeyTheBear]

Well, It Is A New Control Board, I Did Set The Switches Firmly, So I Guess Its Time To Spend Money On The Harman Man,, Or I Could Buy The Diagnostic Tool Myself ,, Saw One New, Online For Sale, Thank You, PS , My P68 Is In My Basement, So That Makes Me A Basement Dweller??

You say your P68 is in the basement, where is the P61-2 that you are having trouble with?

They aren't the same device and they have different dip switch settings.

 

[David E Girard Sr]

Yes I Do Know That, The p 61-2 Is In My Workshop, 25x55 Insulated Barn, It Always Has Done Well In There, 1 Bag Used To Last Around 30 Hours Or So, I Don;t Use The Place Mainly Heated Storage, I Keep It At 50, Which The Stove Would Do On Lowest Burn In Normal New England Weather, If It Gets Really Cold I Turn It Up A Bit, Now With Auto Start I Am Burning I Bag In 24 Hours Stove Set At 50 Feed rate At 3.5 ,But Its Not Cold Outside, I Did Find The Diagnostic Tool Online , Tempted To Buy It, Harman Wants 150.00 To Come Look, The Tool Is 289, Looks Easy Enough , Mechanic By Trade, So Maybe I'LL Give It A Whirl,,,, Love Both The Stoves, They Are Close To 8 Years Old Now And Really Haven't Been A Big Problem, Reliable As And Old John Deere,,, Saved Tons, My P68 Heats Our 1800 Square Foot House, From The Basement, So In Total Its Heating 3600 Square Feet Nine Foot Ceilings Upstairs, If Its Really Cold I Burn 3 Bags A Day , Most Winter Days It Takes 2 , Love It,,,

 

[hearthnleisure]

Sounds like your stove is running on "manual". The toggle switch for the igniter has an auto and a manual setting that if it is on "manual" it will feed for a few seconds every minute because it does not think it has an igniter to restart itself. Even if that toggle looks like it is switched to auto...give it a couple flips and make sure you leave it set to "auto".

If that's not the case, than the new board will take care of it. It's not that the stove is doing anything differently than it ever did before, it's just that whatever you're burning for pellets are burning hotter, causing the esp probe to not get cool enough to shut down. The newest boards have changed the temps required for shut down, therefore eliminating that problem.

 

[Lousyweather]

agreed with folks above....the board......it worked well for several years, started messing up, you replaced the ESP, THAT didn't work......the board.....

 

[Pkcal]

Original poster with the P68 that wouldn't shut down closing the loop. As you all suggested, since the ESP was new I replaced the board and all is good. Shuts down VERY quickly when turned OFF and runs perfectly. Another difference I notice is the new board has a 'detent' on the fan control pot that signals when the pot is set to 'off' My old board was either completely worn out where so you just lined up the knob and/or waited for the circ blower to cycle down to know the pot was in the right place (stove came with the house so no clue if it was this way from the factory or an upgrade with later versions of the board). Thanks again for the help. Saved time and definitely some cash.