Hello-

As you can see, I am a newb to this site and sort of a newb to burning corn. I bought and installed a Greenfield about 2 months ago in my single level ranch style home, roughly 1200 ft². My parents, cousin and uncle have been using the same stove for about 5 years now with no trouble. I, however, have been experiencing what I consider to be low heat output and excessive sooting of the stove and vent pipe.

My stove vent is installed in a direct vent manner straight through the exterior wall and terminates with a 45° elbow pointing towards the ground. I am pulling combustion air from outside through a 2" flexible tube. Exhaust piping is about 2' long and same for the combustion air intake tube. I do not have a vertical rise in the exhaust pipe. This is an approved installation manner as per the install manual.

I have run about 25 bags of corn through the stove to date in the past 2 months. I had trouble right off the bat with the control board locking out on the #2 code. I eventually diagnosed this to a bad vacuum switch which was an intermittent problem, replaced and everything has been just fine with the control board. I have always suspected that my stove heat output has been low in comparison with the others as per my family members. I also seem to be generating a high amount of dark black soot in the stove and on the glass. I have been told the glass accumulation should be white and powdery which will wipe right off. I need to scrub and scrub the black off with major effort. I have also accumulated about 1/8" to 3/16" of hard black crusty residue inside the exhaust pipe. To me, this indicates I am not moving enough primary air through the stove to provide proper combustion. I also think if more air was moving through the burn pot, the fire would be hotter and my heat output should increase. My intake air damper is all the way open. When comparing my stoves' operating characteristics with that of my other family members, it seems that this is abnormal. When questioning the dealer I bought it from and subsequently Tech Service, I found out I should be running about 0.30" WC draft in the fire box. I am running between 0.10" to 0.15" WC. These are "hot stove" figures. So this supports my theory I need to move more combustion air. I am still waiting for a response from Tech Service pertaining to a possible solution.

I spent about 2 hours last night cleaning the entire stove including the combustion air blower wheel, exhaust piping, heat exchanger behind the firebox and behind the ash doors. Major amounts of dark colored ash were removed. Upon lighting the stove and allowing it to warm up, I can definetly see a difference in the flame (it's not as lazy) but I am still running 0.15" WC draft.

I do not believe the corn to be the problem, we all are burning the same corn from the same supplier.

I took a short video of the stove on all 5 heat settings last night and wanted to compare if the flame was "about right" with more experienced users.

Youtube Channel

Can anyone comment on the above?

Sorry to be so long winded!

Stew0620

Hi Stew,
Was this stove new, or did you buy it used?

now that you have a clean stove Try closing your draft on the intake and see if your vacuum gets closer to 30" WC
Also make sure you don't have a leak around your ash door gasket or the door. also I know of an aburn stove that the metal flange of the hopper and fire box was not clean of welding slag and there was a leak there. Maybe a smoke test to see if your drawing in air other than the intake of the stove.
your flame looks ok but could be a little sharper.

when I start to get black on the window I have waited to long to clean

naturesheat wrote:


This is a brand new stove.

hmve wrote:


I can get it to 0.30" doing this but I have to close the damper almost all the way. According to the install manual, they want you to make adjustments in only 1/2 turn increments of the damper stop at a time, which is not really much adjustment of the air damper. It just seemed totally wrong to have to almost choke off the intake air that much to achieve the draft setting. Maybe I should try it and see what happens.

I just edited my post Check for air leaks

hmve wrote:


I have looked at this area several times but I will look again, especially for the welding slag. I have pushed on the ash door to close it tighter and saw no increase in draft but I will take a closer look. All the door seals seem to be in good shape.

I thought about a smoke test too, I will check and see if I can grab a smoke bomb from work.

Edit: Smoke bomb in hand, will try tonight and report back.

Smoke test complete. Only place I can find with a slight leak is at the hinge on the ash pan door. Covering the hinge area temporarily with masking tape has no appreciable change in draft on my magnehelic.

I dug out my electronic thermometer probes and will drill a small hole in the exhaust pipe to insert a probe. That way I can experiment with closing the intake air shutter and noting the change in exhaust gas temperature and also room air discharge temperature. This is still counterintuitive to me though, the hard crusty black buildup in the exhaust tells me I need more combustion air. No time tonight, had to complete snowblower repairs in case I need to move snow in the morning before work.

Thanks to all who have responded, any other input would be appreciated.

hmve wrote:


Well there may be merit to this. I closed down the air intake damper last night quite a bit to get the draft up to about 0.25" WC and picked up about 30° higher room air discharge temp. I was able to hold the house 4° warmer than I could before at roughly the same outside ambient temperature. I haven't installed a probe in the exhaust yet and time will tell about the sooting. My instinct is this should increase the sooting, so I have no idea if what I am doing is correct. Again, it seems odd to me that I would need to close the air intake damper so much when the install manual only talks about very small adjustments in extreme cases.


hmve wrote:


For reference, how in depth of a cleaning do you do on a regular basis? Shut the stove off and clean the entire firebox area including behind the ash doors?

I clean my SCF-050 weekly, and that involves:

1) running a brush through the exhaust vent to remove ash
2) cleaning out ash from behind the little doors (rubber hammer back of stove, run a coil of wire (like an engine choke cable housing) up in there to knock down more ash, then vacuum.
3) remove burn pot and soak in water to remove deposits.
4) remove sliding bottom mechanism of burn pot and dump out any ash
5) soak deposits off heat deflector, but every other week or so vs. every week
6) run a putty knife between heat exchanger tubes to remove more ash
7) clean cool window with windex glass cleaner and paper towel
8) remove and vacuum off air filter
9) empty ash pan in the garden

A note on the black deposits - not sure that's entirely related to air flow. I find that I have more black on the glass when running at low heat level 1 vs. when I am running on 3 or 4.

A note on air flow - I have permanently plumbed a magnehelic gauge into the vacuum line and attached it to the outside of the furnace. I can see the value drop slightly over the course of the week as the stove gets dirty, and can see the value vary depending on outside wind direction. I run about .19 or so with the stove freshly cleaned. I draw room air for combustion and exhaust out the back 2 feet to a T, then vertically about 8 feet to an elbow, then about 8 feet to outside.

-- Dave