Can you overfire a Harman pellet stove?

[keep-in warm]

Just as the title says....

I have seen the term overfire and snapdisks in several threads and it got me wondering. Assuming the control board and ESP are functioning correctly, can you overfire a current generation Harman pellet stove?

I own an XXV, but I imagine all current generation stoves would be similar.
Thanks

 

[poconoman]

I THINK it applies more to hand fired stoves. But, if the control board goes array, I ASSUME that an overfire CAN happen. I'm sure someone can give us more insight.

 

[SmokeyTheBear]

All that is required for a Harman to go over fire is for the convection fan to stop or cease rotating fast enough except for the below condition.

Some stoves won't over fire on their lowest settings because the heat exchanger can dump enough heat via convection to keep the snap disc from ever reaching its temperature limit.

 

[SmokeyTheBear]

As an aside over fire has nothing to do with the presence or absence of a particular kind of temperature sensor, it is the state of the stove which results when the stove's temperature continues to rise to the point it becomes possible to ignite a fire outside the firebox.

Pellets in a hopper is one such possibility. In a number of cases a stove will shut down because a snap disc opens cutting the auger motors electricity long before the issue gets out of hand.

I once saw the results of an over fired boiler, I was told it was glowing orange when the power was cut to it.

The end result was I had to replace the boiler because it cracked due to heat stress.

Luckily there was nothing combustible nearby.

A safety device failed.

 

[littlesmokey]

Technically a pellet stove will "over fire" as in burn too hot. But the overfire condition applies to wood burners, were the fire actually runs out of control, super heating without being able to shut it down or control it. Pellet stoves have high limit switches that stop the supplying of pellets to the burn pot. Many completely shut the stove down. Catastrophic failure, such as loss of a fan or complete loss of power allow the stove to stop by not providing combustion air. Hopper fires are very infrequent and not usually due to overfiring, but underfiring where too many unburned pellets back up and smolder in the hopper. All recent stoves have sealed hoppers further reducing this issue.

Basically overfiring applies to woodstoves and could result in damage to the stove, enough that they are no longer usable. I have seen pelletstoves that caught on fire and were ruined, but usually from things like buildup of fines outside the stove getting trapped in the nooks and crannies and eventually catching fire unique from the stove burn chamber. Fried wires and controls are the result. Often this is also from motor failure.

 

[keep-in warm]

Thanks all.....My wife just started to browse the forums and she became very concerned that we run the pellet stove 24/7 except for the weekly scrape/clean/vac.

- of course her concern was with the family sleeping and having the pellet stove unattended. I was sure that with good regular maintanance, we should never have an issue, but it doesn't hurt to poll the forum.

Happy Holidays!
Rob