Creosote

[Mjhco6]

I understand that creosote can form from any wood burning stove. Does that mean pellet stoves are more prone to creosote/chimney fires? Pellet stoves don't burn half as hot as wood stoves and 9x-10 they are burning low during mild cold weather. To me this is a prime creosote situation. I noticed my chimney cap was discolored.. seemed to be just from the heat or possible ash covered. It is raining here today and eventually would like to inspect cap and look down the chimney pipe.

Does this mean I should run my stove in stove mode more than room temp mode? I have a burn indicator gauge I took off a wood stove insert. My Harman P43 is set on room temp mode at 75*, the gauge is reading 150* on my vent pipe. Just looking for some experience and insight. I know cleaning is a big part of maintenance. I'm new to pellet stoves, just installed my P43 two weeks ago.

 

[tlc1976]

A pellet stove is similar to running a woodstove with a small fire burning full bore. Which doesn't build up much creosote. Pellet stoves are adjusted to meter the pellets and air for top efficiency. Also, the pellets have gone through the manufacturing process. They're not raw wood that has possible bark, sap, ice, whatever else. If your stove is burning correctly you shouldn't get anything but harmless ash in the pipe. Which you still have to clean out periodically throughout the season if you want it to keep burning correctly.

My chimney cap has some discoloration and a light crusty buildup inside, which I knock out when I clean it. But only because of the outdoor rain and snow and humidity getting blown around and collecting in the ash, and then drying and making it stick. The pipe leading to that cap is just fine.

 

[Mjhco6]

I see, I cleaned my stove yesterday, was nothing but light tan ash, and a lot of it. I only saw a bit of black on the auger. I kept hearing a helicopter type noise last night and went outside to check if someone was cruising down the dirt road or if something was coming out of the chimney pipe... Neither was the case. Before stove installation those noises were only heard from aircraft, a vehicle coming down the road, or wind. It was a bit windy last night. The noise could have been a function on my stove that I'm not used to yet. I'm using Lignetics pellets which are PFI certified.

 

[tlc1976]

I'm not familiar with your particular stove, several here are.

But in general, have you ever cleaned the passages, and around the blower wheels? That's something that should be done from time to time. I think of that sound when a bearing is going dry in a blower motor, or if the is crud interfering the wheel. Next time it does it, can you temporarily change the speed of the exhaust blower, and then the room blower, to see if it is either of those making the noise? The noise should change with the motor speed. Hard to say what could be going on after just 2 weeks.

 

[Mjhco6]

Yesterday I cleaned the burnpot, heat exchanger, combustion blower/wheel and inspected the flue. All was very clean, as I mentioned there was a bit of dry light grey/tan ash. I will play the blower motor speed next time I hear this noise.

 

[bogieb]

Pellet stoves are less likely to produce creosote if they are running properly. Part of it is that is, unlike woodstove, the exhaust is forcefully ejected by a fan. The Harman's have a probe that actively monitor the exhaust temp ((broken link removed to http://www.harmanstoves.com/Why-Harman/Key-Technologies/Exhaust-Sensing-Probe-Technology.aspx)).

I run my stoves mostly on room temp - only using stove temp during extremely cold spells and never have anything but ash in the pipes so don't worry about the mode you use (except for keeping it the most comfortable for your situation).

May I suggest that you download the (broken link removed to http://www.harmanstoves.com/Owner-Resources/Install-and-Owners-Manuals.aspx)?

 

[Mjhco6]

Just looking for what others experienced and what they have found while running their stoves. I've only have mine for 2 weeks, I haven't lost the manual yet. Thank for all the good info so far!

 

[TonyVideo]

If you start seeing creosote on a pellet stove typically it is starving for air. Pellets typically burn hotter and more complete since there is a combustion blower and overall less but concentrated hot embers than a typical wood stove. Black tips on the flame or a very lazy fire can create creasote. Cleaning the fire pit of any clinkers or carbon and fly ash off the heat exchangers goes along way to maximize the btu's from the pellets and stove itself with no creasote.

Sent from my SM-G930V using Tapatalk

 

[Mjhco6]

I plan on doing an OAK install, I can feel a cool breeze sitting in front of the stove, and definitely at floor level. I just need to find a way to my crawl space and make it look neat.

 

[Mt Bob]

Any ash,any color,as can be different with different pellets,that crumbles,or is dust,is good.If your stove does not have a self cleaning cycle,and you have burned it on low,for 10 hours,or more,I reccomend you crank it up to high,45-60 minutes.Was normal,on older stoves,but stoves have gotten better,and so have most pellets.But,due to design,some stoves can have cold spots,and form a hard or semi hard black crust of creosote.If yours does,just run it on high for a while,right before you shut it down for cleaning.

 

[TonyVideo]

Any ash,any color,as can be different with different pellets,that crumbles,or is dust,is good.If your stove does not have a self cleaning cycle,and you have burned it on low,for 10 hours,or more,I reccomend you crank it up to high,45-60 minutes.Was normal,on older stoves,but stoves have gotten better,and so have most pellets.But,due to design,some stoves can have cold spots,and form a hard or semi hard black crust of creosote.If yours does,just run it on high for a while,right before you shut it down for cleaning.

I also run it on high for 30 minutes before cleaning.

Sent from my SM-G930V using Tapatalk

 

[alternativeheat]

I understand that creosote can form from any wood burning stove. Does that mean pellet stoves are more prone to creosote/chimney fires? Pellet stoves don't burn half as hot as wood stoves and 9x-10 they are burning low during mild cold weather. To me this is a prime creosote situation. I noticed my chimney cap was discolored.. seemed to be just from the heat or possible ash covered. It is raining here today and eventually would like to inspect cap and look down the chimney pipe.

Does this mean I should run my stove in stove mode more than room temp mode? I have a burn indicator gauge I took off a wood stove insert. My Harman P43 is set on room temp mode at 75*, the gauge is reading 150* on my vent pipe. Just looking for some experience and insight. I know cleaning is a big part of maintenance. I'm new to pellet stoves, just installed my P43 two weeks ago.

Harman does a very good job of keeping the air to fuel ratio correct and exhaust stack temps up so as not to build creosote at all in the vent pipe. Usually you will just get ash out of your vent, pretty much as you see inside your stove when you clean it. If creosote is building in the venting of a pellet stove it's usually installed incorrectly or otherwise burning wrong. Exhaust gasses going out the vent of a Harman stove are generally over 300 deg f. Even in a low burn the air quantity is kept pretty safe for the amount of fuel used in a Harman. No creosote is built that a good hot burn won't eat up at any rate and at that it is usually confined to the inside of the stove someplace ( like the end of the auger as you mentioned, as can carbon build there). I think you can stop looking at your chimney in concern of a chimney fire, it's very unlikely to take place. All I ever get out of my P61 venting is ash and it runs up 32 ft to the top of my brick and mortar chimney through a 4" liner.

Incidentally, I hear that the enviro block fuels for wood stoves put out very little creosote as well. They are the same principle as pellets on a giant scale. Burn those in a stove that gives the fire secondary air and very little chimney fire danger there as well from what I hear. But the pellet stove goes one step further by injecting air through the fuel and flame. Harman one step beyond that and monitors exhaust gas temps. Emissions are very low minus the ash, thus why all the environmentalist friendly ratings on them, not to mention the so called renewable fuel source.

 

[batchman]

If your stove is burning correctly you shouldn't get anything but harmless ash in the pipe. Which you still have to clean out periodically throughout the season if you want it to keep burning correctly.

I'll echo this, I had the same concern, so for the first few years I had my "chimney guy" do the pellet stove vent as well as my insert. He stopped on his own volition, said there was no need.

All I ever get out of my P61 venting is ash and it runs up 32 ft to the top of my brick and mortar chimney through a 4" liner.

In my case I did not line my masonry chimney because I kept looking at the physics and though it shouldn't be necessary. My chimney was slightly larger than recommended (replaced a wood stove that wouldn't draft, basement room problem) but I chose to save the lining (building inspector was fine with that decision) pending "chimney guy" results - voila - no concerns.

Incidentally, I hear that the enviro block fuels for wood stoves put out very little creosote as well. They are the same principle as pellets on a giant scale. Burn those in a stove that gives the fire secondary air and very little chimney fire danger there as well from what I hear.

I burn about 1/2 cordwood and 1/2 "giant pellets" in my upstairs insert. My experience contradicts your "very little" comment. In my (lined) 24' chimney I get a couple gallons every year. I suspect that it's partly because it's an "outside" chimney, and partly because it's difficult to get the giant pellets to burn consistently through their run. I really thought I was running it hot enough to prevent this, but turns out not to be the case, at least for me.

Cheers,
- Jeff
PS what happened to the search function? I came back to update a reply that I do not recall where it was, and I can't find my past posts never mind search for a keyword.. I predict many more duplicated threads!

 

[alternativeheat]

In my case I did not line my masonry chimney because I kept looking at the physics and though it shouldn't be necessary. My chimney was slightly larger than recommended (replaced a wood stove that wouldn't draft, basement room problem) but I chose to save the lining (building inspector was fine with that decision) pending "chimney guy" results - voila - no concerns.

I burn about 1/2 cordwood and 1/2 "giant pellets" in my upstairs insert. My experience contradicts your "very little" comment.

Cheers,
- Jeff

I read over in the wood burners forum that all of those enviro blocks for wood stoves are not created equal and like pellets it also matters how they were stored before you buy them. Also a stove with secondary air makes a big difference with wood or blocks. FWIW, I was looking into this for a basement install of some sort of stove but so far continue with kerosene (illegal in our state now, though it's worked down there in my shop for decades). I'll probably go with another pellet stove though for ease of lighting as I need it and control of burn..

The standard existing chimney install around here is to run a liner up the chimney. Made sense to me, especially given that my chimney has no clay liner anyway. All I can say it is works flawlessly, very easy to clean, just run a rotating brush up through there twice a year,let the ash fall into an open pellet bag, have a shop or ash vac handy to suck up the stray dust in the air in the fireplace as the ash falls..

 

[batchman]

I read over in the wood burners forum that all of those enviro blocks for wood stoves are not created equal and like pellets it also matters how they were stored before you buy them. Also a stove with secondary air makes a big difference with wood or blocks. FWIW, I was looking into this for a basement install of some sort of stove but so far continue with kerosene (illegal in our state now, though it's worked down there in my shop for decades). I'll probably go with another pellet stove though for ease of lighting as I need it and control of burn..

The standard existing chimney install around here is to run a liner up the chimney. Made sense to me, especially given that my chimney has no clay liner anyway. All I can say it is works flawlessly, very easy to clean, just run a rotating brush up through there twice a year,let the ash fall into an open pellet bag, have a shop or ash vac handy to suck up the stray dust in the air in the fireplace as the ash falls..

In case I wasn't clear or thorough (either of which can happen with me ),

Pellets - I've satisfied myself (with professional help) there is no need to clean the masonry lined chimney portion of my venting path. I just keep the up-pipe from the stove and the horizontal pipe leading to the chimney clear, this is where ash deposits. I'd reference my build thread but without search or personal post history I can't guess what or when to look for it. I will have to find it eventually, to update progress on my ducting project.

Blocks - (giant pellets) - I've used several brands for several years, basically replacing one log with 1 to 1.5' of giant pellet (depending on brand & geometry). I get a nice secondary burn in my insert, but that can't stay consistent through an overnight - which the blocks genuinely help to make reach morning. I store the blocks sealed in space heated by the pellet stove and dehumidified in the summer. Results are consistent, significant creosote in my stainless lined 20-foot outdoor chimney. As both of the chimney pro's who have serviced it have said, they "really like wood". I just find some user benefit to the blocks and will continue with them, while understanding that the maintenance needed is important.

YMMV,
- Jeff

 

[alternativeheat]

In case I wasn't clear or thorough (either of which can happen with me ),

Pellets - I've satisfied myself (with professional help) there is no need to clean the masonry lined chimney portion of my venting path. I just keep the up-pipe from the stove and the horizontal pipe leading to the chimney clear, this is where ash deposits. I'd reference my build thread but without search or personal post history I can't guess what or when to look for it. I will have to find it eventually, to update progress on my ducting project.

Blocks - (giant pellets) - I've used several brands for several years, basically replacing one log with 1 to 1.5' of giant pellet (depending on brand & geometry). I get a nice secondary burn in my insert, but that can't stay consistent through an overnight - which the blocks genuinely help to make reach morning. I store the blocks sealed in space heated by the pellet stove and dehumidified in the summer. Results are consistent, significant creosote in my stainless lined 20-foot outdoor chimney. As both of the chimney pro's who have serviced it have said, they "really like wood". I just find some user benefit to the blocks and will continue with them, while understanding that the maintenance needed is important.

YMMV,
- Jeff

Good to know Jeff, since my venting will be outdoors as well. I think pellets are winning anyway, since I can terminate on the same plane as the hot water heater vent or there abouts and don't have to clear the gutter above the rear dormer of the house. it's not happening this winter anyway, I have my stash of kerosene for this winter, by April I won't need heat down there and will be looking to go fishing ( not so far away).