Not generating heat like last year

[dmoyer]

We purchased the 6500 Magnum furnace last year and it easily heated our home on settings 1 or 2. We only needed 3 if the temps went to 0 or below or if it was very windy. The house easily heated to 70 degrees or more. We followed the manual for cleaning and oiling for the summer months and when we started the furnace for this heating season, we can not get anywhere near the heat as last year. The Room Air Fan comes on approximately every 10 minutes. Last year it seemed to run continuously. The air coming out the registers is around 80 degrees, but the fan comes on so infrequently that the house cools the air faster than the furnace can heat it. The house is well insulated - completely rebuilt - new windows, insulation, doors... We do have outside air being piped to the manual draft port. With the furnace on 3 we barely get to 60 degrees - what is going on?? The fire is burning well, the corn is approx 15% moisture - same as last year - the flue temp is about 90 a foot up from the furnace, so the heat isn't going out the chimney. We shut down and clean the furnace thoroughly weekly. We do the daily maintenance of clinkers, and cleaning the heat exchangers... we are at a loss... we even bought different corn thinking the first batch may have had too much moisture, or some other issue, but the heat never improved. Any ideas??

[Technical]

Hi dmoyer,
Have you cleaned out all of the venting to make sure of no obstructions? Have you checked the blower to see if it failing? The blower is a 1 speed, 1/3 hp, 1075 rpms, 1250 cfms, 120 volts and 4.9 amps. When cleaning make sure to clean behind the clean out plugs, depending on the age of your furnace. Have you contacted the dealer that sold you the furnace? What is the static pressure?

[dmoyer]

There are no obstructions. This year the chimney was cleaned. The exhaust pipe was cleaned and checked weekly. The cleanout plugs were pulled and cleaned. We oiled the furnace thoroughly at the end of last heating season, and we noticed quite a bit of surface rust at the beginning of this season. We are at a loss of what to do next. We contacted a local dealer (closest is 30 miles away), he doesn't have many ideas either at this point. He mentioned there might be a hole in the heat exchanger and that could be effecting the heating. He has had 2 furnaces sent back with this issue. Which blower are you referring to? The exhaust blower or room fan? Both are running, but I don't know if the exhaust blower is running at 100%. It appears to be without hooking up any meters to verify. Any other ideas?

[wdf73]

I would try to eliminate the easiest possibility first. If nothing has changed but the fuel, try a different fuel and see if it makes any difference. Corn can vary greatly from year to year in test weight, kernel size, starch content, etc. Even more dust or fines can greatly affect your heat output.

[jimmyro]

Dmoyer, I have a 7500, and seem to have the same problem as you are having.

Have you come up with a answer?