high exhaust temps. inefficient, or just me?

[chuey_316]

I have a cornflame 3000 centrally located on the 1st floor of a 2 story 1500 sq. ft. home. Thermostat is about 5-6 feet away from the stove, and is only used to see the temp in the room. Past week or so, the temps have been between 67-69º, mostly 67. I'll make subtle tweaks to it over a 3 or 4 hour period after work, and get the temp up to 69-70 before bed, then in the morning it's 67 again. Hell, this morning it was 65º

Temps outside are in the low to mid 30's right now, although a couple of the days were in the mid 40's, and other than tonight there's been no real wind to speak of. My exhaust goes through the wall into an enclosed, but not airtight by any means porch, and up through the roof, I also pull my fresh air from the porch.

After monitoring the output temps the past few days, here's what I've found: With a feed rate of 7, and the room blower at max, or just under, I'm getting temps fluctuating between 300-320º inside an exchanger tube, and 160-180º about an inch or two in front of the grill. This is using a 6" probe thermometer.

A little bit earlier, I pulled the cap from the clean-out tee, and inserted the same probe into the exhaust and got a temp of 380º and rising when I pulled it out. This is with the intake already about 45% restricted. I blocked it off a little more, (about 55-60% or so) but then there didn't seem to be much air flow coming out the bottom of the tee at all, so I uncovered it back to where it was.

Is it just me, or is the exhaust temp a bit high? Seems like some of that heat could be staying in the house.

Clinkers are greyish white, as is the ash in the chamber. No problems with the pot overflowing, although I haven't run it any higher than 8. Flames are active with some blue down around corn level, then bright yellow.

[chuey_316]

Oh just too add, the corn is clean. It's been through the kan burn, then a manual screener to remove fines. There's a small amount of cracked corn, but hardly any really. Not sure on the moisture content, but it's dry. Cracks easily and when I asked the elevator, I was told that they dry all their corn to between 13-14%

[Craig]

Thoroughly cleaned the heat exchange tubes?

Is the room air blower working?

Intake and exhaust tubes are clean?

Some hybrids of corn burn differently and hotter than others.

Have you tried some corn from a different vendor?
_________________
My Therapist Recommends Shock Therapy.

[chuey_316]

Heat exchanger tubes cleaned with a toothbrush, blower working, intake clean, exhaust I'm not sure. Going to pull it apart tomorrow and make sure there is no restriction.

This is a problem that I've had with the stove since almost day one. Even with the stove clean as a whistle, and different varieties and moisture corn, I can't the the output to reach it's full potential.

The output temps don't seem too far off though, just the fact that the exhaust temp is near or over 400º tells me that I'm losing heat out the exhaust that I should be keeping. If I restrict the intake anymore though, I'm not getting much exhaust flow.

I'm really starting to wonder if the vertical length is what has been giving me problems the whole time. My vent goes about 1ft through the wall to a tee, then 12 or 13ft vertical if I remember correctly. The intake pipe is a little under a foot long.

Really wish I could just run through the wall, and a 3ft vertical and terminate, but it's just not possible where the stove is at. it would be exhausting onto the porch.

[cowtrimmer]

I have a long run with my snowflame. 3 45degree angles and 5-6" of run. I have always had a high heat output unless I have ran higher moisture corn. This year I installed a negative pressure exhaust and I am experiencing the same thing as you. I'm gonna try to choke down the input air.

[chuey_316]

Went ahead an just pulled the vent apart tonight. There's slight ash/soot buildup but it's not restricted in the least bit.

Left the stove running for a short time (about a 1/2 hour) with just the tee connected and the intake unrestriced to see if the output temp would rise without the vertical run, and it actually dropped another 40º

Best heat I ever got out of it was when I had a rheostat inline with the combustion motor to slow it down. Was getting dirtier burns though, but the heat output was higher. Somewhere between 25-50º more. The rheostat started to get very unreliable though, so I unhooked it.

I'm half tempted to get a heavy duty one, and turn the combustion air down to slow the exhaust some, open the intake all the way and just open the tab on the fire pot if need be. Had our 1st snow today, and it's supposed to be a cold winter here this year. I can't fight this thing all winter long like last year.

[chuey_316]

60º in here this morning. About to look on craigslist for an idea of how much I can get out of this thing. I really need something bigger, at least 50,000btu, and the fact that it's not a biomass stove like the company states in order to sell them, has left a bad taste in my mouth since the day it arrived.

[chuey_316]

Got home from work, and the ol lady let the corn run out while I was gone, so it was just pumping air the whole time. It was 66º in the house, and I decided it was a good time to tear the stove apart and do a thorough cleaning.

I cleaned the entire inside with a toothbrush, cleaned behind the backplate, vacuumed out the exhaust behind the square plate, and pulled both the combustion and room air fans and cleaned them as well. Then I readjusted the pin and lit her up.

The temp raised from 66º to 69º in about 45 minutes, then about 1/2hr-1hr later the temp is back around 60º again. The temp outside hasn't dropped but 2 or 3º if any, and the wind is no more than earlier, at 4mph.

The stove has been running on 10 for the last couple hours.