Lazy, Smoky Flame on High Settings - St. Croix

[TheDarkSide]

Time to check with the experts.

I have a St. Croix Prescott EXL, bought in 2006 brand new, that has had some issues with lazy flames and wisps of black smoke when running on the higher levels ( 4 & 5 ). I do have an OAK installed. My particular setup has the larger diameter pipe with the exhaust pipe inside that. It goes up from the stove about 6-7 feet and then 90 degrees outside. The outside air is pulled in around the exhaust pipe to the bottom and then directed into the stove ( I hope this description makes sense ).

Here is what I have done this year. I pulled out all removable pieces(grates, burn pot, ash trap doors, metal "brick" walls ) and vacuumed everything. I used a rubber mallet and tapped the back of the firebox and vacuumed up that ash. I did my best to snake a brush in the ash trap doors to loosen up ash, etc. and vacuumed ( my '06 stove doesn't have the 3rd ash trap in the tray compartment ). I removed the exhaust fan and brushed it clean and vacuumed that area.

Next, I went outside and snaked a 3" brush up and down the exhaust pipe 3-4 times to clean that out. Lastly, I use the LBT to get whatever loose ash was still in the stove, first with the door open, then with it closed. I ran the blower until there was no more ash coming out. I seemed to get a lot of ash out this way.

All motors and fans seem to be working fine, including the versa-grate motor.

Except for the ignitor that just went (should have the replacement today), the stove starts up fine. The first pellets get burning and the flame is huge, which I expect, but it seems to burn clean. Now this is where the trouble comes in. After a short while, the flame gets lazy, huge, and black smoke rolling of the tips. It almost seems like the pellets feed too fast and fill the pot too quickly. Burning on settings 1-3 seem fine ( nice sharp flame, no smoke or black soot on glass ) but 4 and especially 5 do not burn clean. I can't be 100% sure, but I believe the door seals are still fine, although they are original equipment. And like I said, 1-3 burn fine. I do have the damper level almost horizontal with the floor, which I believe is almost fully open, but that seemed to be the best setting for level 3 when I was adjusting it.

I am burning Green Supreme pellets that I got from Lowes ( manufactured by NE Pellet, I believe ). I burned these pellets last year but can't remember if I had this same trouble or not. I want to say it is worse this year than any other time.

So any ideas on where I should look? I am a homebrewer and have some spare 1/2" vinyl tubing which I'm going to rig up to my shop vac to see if I can get the area behind the fire box cleaned out any better, but I did get a lot of stuff using the mallet trick.

Thanks.

 

[SmokeyTheBear]

Is your versa grate working? Is the coupling to the motor connected securely?

Are all of the slots in the burn put system clean and to full size.

Do a lot more taping on that back wall

Also remove the combustion blower and clean the vanes on the impeller and between the impeller and the motor mount plate. Be certain to have a replacement gasket on hand before doing the combustion blower pull and clean.

Test your combustion blower to make certain it spins up to full speed after you have cleaned it.

ETA: Test those gaskets looking doesn't mean a thing.

 

[TheDarkSide]

Is your versa grate working? Is the coupling to the motor connected securely?

Are all of the slots in the burn put system clean and to full size.

Do a lot more taping on that back wall

Also remove the combustion blower and clean the vanes on the impeller and between the impeller and the motor mount plate. Be certain to have a replacement gasket on hand before doing the combustion blower pull and clean.

Test your combustion blower to make certain it spins up to full speed after you have cleaned it.

ETA: Test those gaskets looking doesn't mean a thing.

Thanks Smokey.

Versa Grate is working I believe. I have observed the rod extending out and retracting in through the front bushing and the shaker plate is firmly set over the spacer.

All the holes in the burn pot are clear. I clean those out when I empty ash and clean the stove.

I will try more wall tapping. I will also try to get something better for reaching up in the area ( vinyl tubing - stove cold of course ).

I removed the combustion blower and brushed all the areas clean and replaced the gasket when doing so. How do you test to make sure it is up to full speed? As far as I can tell, it seems to be running full ( i.e. no stuttering or slowing that I can see ).

I assume you use the paper trick to check the gaskets, on both the main door and ash pan doors?


P.S. Nice list of homebrew. I also have a stout, pale ale, cider and mead going right now.

 

[SmokeyTheBear]

Yes on the dollar bill (paper trick) test for checking the gaskets. Never trust a visual gasket check.

When you cleaned the area the combustion blower was in did you get the mess off the blades as even a little rounded ash instead of a nice sharp edge on those blades causes you loss of valuable CFMs.

Did you also check that your damper was still positioned correctly? Things do get hit.

If there is a local motor repair place they can check the RPMs of your blower.

I use the old fashioned method of hooking up a suicide cord and plugging it in to the wall outlet, it should start right off and quickly speed up, then pull the plug and it should still revolve a bit before stopping. You can also spin it by hand and it should turn a little bit after you stop spinning it. I know not scientific but it gives you a pretty good idea if things are still turning freely and somewhat properly seated as far as the impeller goes.

 

[heat seeker]

Smokey mentioned the intake air damper - is that open at least a pencil's diameter? (Assuming it's built like my St. Croix.) Have you tried running it with the OAK disconnected? It may have a restriction in it.

You could take a mirror and flashlight and look down the back of the firebox to make sure it's clear, after pulling the
exchanger rake forward out of the way. I'd hang a rag on the handle so you don't poke your eye out on it. Don't ask.

You can also use the mirror and look up through the ash traps on either side of the burn pot. If it's clear back there, at least you can eliminate that area. The Leaf Blower Trick might help with ash caught in the passage behind the ash pan.

If it's been running poorly on higher heat levels since day one, I'd suspect a restricted OAK or inlet, or venting. I can run mine on high all day long, and the flame stays lively.

One other quick check, adding to Smokey's comment - when I shut my combustion blower down, it coasts for quite a while maybe as long as a minute or so (never timed it). If yours doesn't coast for a while, it may be defective, or not spinning fast enough. On high, it should be receiving nearly full line voltage.

 

[TheDarkSide]

So I did the dollar bill trick last night and it resisted but I was able to pull it out. So I figure I need to redo the door seals. I also figured I might as well give it another good cleaning, so I removed all the grates, trap doors, metal walls, etc and tapped on the wall with a mallet again. I also took the vinyl tubing and snaked it up behind the firebox. I cannot believe the chunks of ash ( more like rocks ) that fell down. Now I was very motivated. I spent the next hour, tapping on the wall, snaking the vinyl and vacuuming up the ash. I cannot believe the extra amount of stuff I got, especially since I already did a lot of this about a month ago. The only difference is that I didn't using the vinyl tubing last time.

Now it burns like a champ. I'm sure the door seals should be replaced as well but now I feel like I have time. I've been running it today on 5 for about 30 minutes and not one wisp of black smoke and the window is very clear.

Now I need to come up with some device other than the vinyl tubing. It worked well enough but it isn't rigid enough to break through everything I think. I will keep it and use it with a drilled rubber stopper on my shop vac as an extension for vacuuming out behind the firebox and in the tight spaces.

Thanks for all the suggestions.

Heat Seeker...I took off the OAK last night and checked for blockage as well. There was nothing but a good tip to remember for the future. The nice thing about mine is it's integrated in the the wall thimble so I don't need to worry about mice or birds nesting like the try to do in the exhaust pipe ( duravent system ).

 

[SmokeyTheBear]

Hint when doing the LBT make sure you leave it running when doing the taping routine.

Your exhaust system is a little tricky to get every thing out of, once you do get it cleaned a good suction job will keep it that way.

 

[heat seeker]

I'm glad you got it! Some owners use a piece of flexible cable housing fed through a hole in the back wall, and attached to a drill. The housing whips around back there and knocks any crud loose. The two holes are then plugged with metal plugs available in a hardware store. Somewhere, I've seen the locations of the two holes, so you can drill them yourself, but I can't remember where I saw it.

I have, on occasion, used the pot scraper tool, hung over the back wall where the heat exchanger tubes pass through, to scrape back there. I've never had anything of significance to scrape or knock off, so don't bother any more. I take a look occasionally with a mirror and light.

I never run my stove under setting #3, unless it's in low mode on thermostat, and then it's only for 10 or 15 minutes at a time. I'd say 95% of the time, my stove is running on #3 or higher, and perhaps that's why my passages aren't crudded up. The manual says to run the stove on #5 for, I think, 20 minutes a day at least, to burn out any remains.

Anyway, enjoy the heat! I just gave mine a good cleaning this morning, and am basking in the glow.

 

[ghandy131]

I hate to say it, as I have 3 tons in the garage, but its the GS. They're dirty, dirty, dirty. Doesn't matter what you do, they'll burn tough. I've found by mixing 1 to 4 parts Turman and GS the stove keeps cranking. Every 3 bags of GS I then run a half bag straight of Turmans and it cleans out the pot and burns the black soot off the glass. I actually need to hot scrape the pot once or twice a day to keep the clinkers from blocking all the holes (only takes about a minute). They must have injected them with salt this year.