Harman Invincible shut down issue

[Tim_M]

I’m having an issue with my old reliable Invincible T (‘93). If it runs out of pellets it doesn’t go into shut down mode, rather the auger motor continues to run until I manually press the shut down button. Would this be a control board issue, or possibly an ESP problem? It’s not really a big deal to just push the button to shut the stove down, but I’m a bit worried that whatever is causing this may get worse and cause other issues as well.

 

[DAKSY]

Start with the ESP.
It is supposed to shut the unit down when it hits 90 Deg. F.
Pull it & see if it's covered with soot or damaged.
Clean it & try it.
If it still doesn't shut down, change it out.

 

[Tim_M]

Thanks I have cleaned the ESP as part of my pre-season cleaning but that didn’t seem to help. Aside from this one thing the stove seems to work normally. I had to replace the ESP when I first got the stove 10 years ago. Maybe time to do it again.

 

[sandpipe]

Tim, did you solve the shutdown prob?

 

[Tim_M]

No I’ve been shutting the stove down manually so far this season. There are no issues at all when I do it that way. The old warrior is otherwise working great so I’m reluctant to mess with it. Or shell out $$ for a new ESP or board (assuming I could even locate them). I tend to think it’s a problem with the board rather than the probe.

 

[Washed-Up]

It’s a few bucks, but Pellthead has them

https://pellethead.com/product/harman-circuit-board-control-panel-manual-start-models-oem/

 

[sandpipe]

I had to replace the board on my Invincible a few years ago. I forgot to plug into a surge suppressor/battery backup, and an power outage damaged the board. It still worked but the circulation fan was very erratic and not responding to the control dial. If the only problem was an auger turning I probably would have held off on the expense too.

 

[Hoops32]

The Invincible "RS" (room sensor) models, but not sure about the "T" (thermostat) models, had a micro switch that the arm on the gear motor would make contact with on each revolution, this would send a signal to the board that the slide plate inside the feeder body was in the "closed" position. If the micro switch is bad or the tab on the switch is bent out of position, it will continue the feed cycle until the stove runs out of fuel or you cut the power.

Copied from the "RS" manual: 2 Blinks: Indicates that the feeder position switch has not sensed the slide plate in the home position for 30 minutes. This means that the slide plate may be stuck due to a foreign object in the fuel or the switch has failed. If the switch has failed the stove will operate normally, however if turned to the "OFF " position the stove will go to minimum burn and will only shut down when it runs out of fuel. If the slide plate frees itself the status light will automatically reset