Pellet Stoves and Fire Hazards Associated?

[AlaskaCub]

I have an interesting question, I am well aware of the fire hazards associated with wood stoves (chminey fires primarily) but I seldom hear of fires in homes started by pellet stoves. Can someone give me a little insight to why you seldom hear of pellet stove fires. Is it cuz the pellets burn cleaner, less creosote?

FYI we responded to a house fire a little while ago and the wood stove that was installed TODAY, first fire in the pipe burned half the house down. So talk of chimney fires has been an active topic today.

 

[webbie]

Almost no creosote - the fuel is consistent, low moisture as opposed to whatever the homeowner decides to burn.

 

[AlaskaCub]

Thats what I fgured but what about chimney temps, are they cooler with the pellet as opposed to wood?

 

[cac4]

I don't have any factual data, but I do remember checking out the pellet stove displays at the county fair...stove dealers have units sitting outside, running, so no chimneys attached. I put my hand up to the exhaust, and it only felt luke-warm. the part that points into the house was much, much hotter. (of course, I don't remember how much of a fire was going...).
think about the exhaust pipe: only 3"...only needs an inch clearance to combustibles...(the newer pellet-pro, anyway). its "not that hot".

I think the word "stove" is kind of a misnomer, for these devices. They're complex, highly regulated hot-air furnaces...fired by wood...that look vaguely like a "stove".
I bet you don't hear much about oil or gas furnace fires, either. I mean, I'm sure it can happen; just not as likely as an uncontrolled pile of burning fuel in a box, thats gonna do whatever its gonna do.

 

[webbie]

Probably most danger with pellet stoves is "burn back", meaning the pellets burn back into the hopper - but this is usually a very slow process when the power goes out, etc. - since there is not a lot of air flow through the pellets.

The stack temps are much lower due to a lot of air throughput and long heat exchangers, etc.

 

[mralias]

I'd be more worried about electrical failure in the stove to cause a fire then the pellets. How many of those has anyone heard of?????? Anyone????.........Hello????



Thats what I thought.

 

[Xena]

Thats what I fgured but what about
chimney temps, are they cooler with the pellet as opposed to wood?

Pipe temps are far cooler. I can hold my hand on the T cleanout and
not get burned.

 

[Don2222]

Hello

Well your in luck now, I found some!! Although wood pellet stoves were involved in the fires there still can be the human error factor! Sometimes an improper install. Pellet Vents should have a 5 foot vertical rise to prevent blow back, but I have seen many that go straight thru the outside wall of the house

See Posts Below with Pics of 15 I found That is over a Baker's Dozen!!

1. One explanation of a house fire caused by a pellet stove!!
https://www.hearth.com/talk/threads/71839/

2. House full of smoke
https://www.hearth.com/talk/threads/69470/

3. Late-night Georgetown MA fire destroys North Street barn caused by Wood Pellet Stove Ashes!
https://www.hearth.com/talk/threads/74138/

4. Apr 8,2011 - Pellet Stove Blamed for Small Sunnyside House Fire
https://www.hearth.com/talk/threads/73966/

5. More Info on Derry NH House Burning Down now maybe related to the Wood Pellet Stove according to the Fire Dept!
https://www.hearth.com/talk/threads/67166/

6. Pellet Stove Malfunction causing this house fire??
https://www.hearth.com/talk/threads/74756/

7. Ashes from a pellet stove cause fire in Springfield home (Hot ashes in plastic vac melt thru enclosed porch floor!)
https://www.hearth.com/talk/threads/73968/

8. Pellet Stove Causes Smoke-Filled Home in Raymond Nebraska
https://www.hearth.com/talk/threads/74588/

9. Pellet Stove Fire Damages Champaign County Home in Ohio
https://www.hearth.com/talk/threads/74582/

10. Stanton St. Fire Caused By a Wood Pellet Stove - Actually combustibles near the exhaust!!
https://www.hearth.com/talk/threads/74298/

11. A small wood-pellet stove malfunctioned causing a Fire that does minor damage to Braintree MA home
https://www.hearth.com/talk/threads/74137/

12. vent fire in a pellet stove
https://www.hearth.com/talk/threads/74078/

13. Ashes thrown into a combustable container from a Wood or Pellet stove start a house fire in Keene NH
https://www.hearth.com/talk/threads/73750/

14. She put hot Ashes from pellet stove in garage and guess what happened in Merton WI house? - Waukesha County
https://www.hearth.com/talk/threads/72309/

15. OMG Scary Hopper Fire
https://www.hearth.com/talk/threads/66820/

Almost forgot the now famous Original Ludlow MA Wood Pellet Stove Fire that was all over TV!!
See TV News video in link below Pellet stove sparks Ludlow fire
(broken link removed)

LUDLOW, Mass. (WWLP) – A pellet stove is to blame for an early morning house fire in Ludlow. But a twist of fate may have saved the life of a ten year old, after flames destroyed his bedroom. Manny Marques built his Ludlow home with his own two hands and wasn’t about to watch it burn. Although his face was burned after he threw water on the flames until the fire department came. “I have a lot of damage in my house, but if it wasn’t for my husband I would have a lot more,†said Eva Marques. Their entire family came to comfort the couple. “We’re a big Portuguese family and were here to help each other,†said the fire victim’s niece, Carmen Bastos. Early Saturday morning flames broke out in the back of 23 Richard Rd. Investigators believe a clogged pellet stove that caused the fire. It left about eighty thousand dollars in damage; mostly to the Marques’ grandson’s room. David typically sleeps there every night, but for some reason on Friday he insisted that he slept downstairs with his grandparents and everyone agrees it certainly averted a tragedy. “Something told me, he kept bugging me to sleep downstairs and I gave in and thank God I gave in. I have a lot of damage, but it’s a house and my little one is okay and husband is okay,†said an emotional Marques. The family is staying with family for a few weeks while their home is repaired.

Search words for this post. Wood Pellet Stove House Fire Pellet Home Fire

 

[CJ-SR4ever]

I'd be more worried about electrical failure in the stove to cause a fire then the pellets. How many of those has anyone heard of?????? Anyone????.........Hello????



Thats what I thought.

First id like to say, good info Don, as usual! If a pellets stove loses power while running, the fire will just smolder and go out after a while. You may get a little smoke in the room depending on how you venting is set-up. In my experience, house fires caused by pellets stove is usually caused by user error or if the stove is not vented to code. Most stoves these days have safety features built in that will make the stove shut down if the venting is clogged.

 

[Don2222]

I'd be more worried about electrical failure in the stove to cause a fire then the pellets. How many of those has anyone heard of?????? Anyone????.........Hello????



Thats what I thought.

First id like to say, good info Don, as usual! If a pellets stove loses power while running, the fire will just smolder and go out after a while. You may get a little smoke in the room depending on how you venting is set-up. In my experience, house fires caused by pellets stove is usually caused by user error or if the stove is not vented to code. Most stoves these days have safety features built in that will make the stove shut down if the venting is clogged.

Yes, CJ

If the wood pellet stove flue vent is clogged there is a vacuum pressure switch also know as a flow switch. The switch connects to the plenum that the exhaust fan blows into by a small plastic tube. The exhaust blower creates suction in this tube that pulls in the switch diaphragm and closes the a set of contacts, which means the stove is operating properly. If the vent is clogged then the diaphragm falls back and opens the switch contact shutting down the auger.

See http://www.thepelletstovecorner.com/tips-ideas/the-vacuum-pressure-switch/
The switch is easily identified because it is connected to hose or tube of about 1/4″ diameter that runs to the exhaust fan housing or somewhere on the stove body that communicates to typically a negative pressure environment created by the exhaust fan. The idea here is that the exhaust fan, downstream of the burnpot, is “sucking†the smoke, heat, and particulate created by the burning pellets, in turn, fresh air is drawn through the holes in the burnpot providing the oxygen and turbulence required for a continued efficient fire. There is a diaphragm located within the vacuum pressure switch, as long as the exhaust fan is doing its thing and the required minimum negative pressure is maintained, the diaphragm is pulled closing the switch allowing electricity will travel across it. The switch is hooked up to the auger motor. So, if the exhaust fan fails or the stove door is left open the auger motor should stop feeding pellets to the fire. Or, if your stove or flue is clogged up the auger motor should stop feeding.

To review, the vacuum pressure switch allows the auger to run as long as there is sufficient negative pressure.

If you are sure the exhaust fan is running properly and the stove and flue are clean, and the auger appears not to be jammed and you are positive that all doors are sealed, (check the ash drawer door), and the auger motor fails to turn, you very well may have a problem with the vacuum pressure switch.

The first thing you want to do after you unplug the stove is examine the hose looking for a break, if its broken the break will most likely be where the hose connects to the stove as that is where the hose is exposed to the most heat. Next, disconnect the hose from the switch and see if you can blow air through it. If you can’t you will want to ream out the metal tube that the hose connects to with a stiff wire.

If none of the above corrects the problem you will want to bypass the switch temporarily to see if it needs replacing. The switch will have two wires connected to it, but some switches will have three places to connect to so take a good look before you disconnect the wires from the switch. A simple trick to bypass the switch is to use a flat type automotive fuse and connect the wires from the switch (they have female spade type connections) to their male counterparts on the fuse. Check it out, does the auger work with the vacuum pressure switch bypassed? If it does and the fire burns bright and clean with no sooting of the glass then you will need to replace the switch. I do not recommend leaving the switch bypassed! It is a safety feature designed to shut off the auger in the event of a exhaust fan failure or a flue blockage.

Also see pic below: