USSC 5510 draft fan stops working. Is this an overfire problem?

Could be just plain ash in the works that is causing your problem.

If the venting is restricted and you attempt to move a lot of very hot air through it the temperature the draft fan sees can get at or above its designed 475 thermal shutdown limit. This usually results in a loss of vacuum shutdown which can be followed by a high limit trip.

Normally an over fire condition is when the room fan can no longer remove enough heat from the heat exchanger and dump it into the room causing the heat exchanger to reach its high limit usually somewhere in the mid 200 range at a specific point on the exchanger (the usual cause in this instance is the room or convection fan shutting down or failing).

ETA: Some stoves are not meant to be fired at their top rate for any amount of time, you should check your manual to see if yours has this limit.

Screamin Rebel said:

Thanks Smokey! The stove will run fine all day on the highest settings, its has the problems in the morning when the thermostat ramps up from 68 to 72. Could see restricted exhaust causing it but cleaned stove and exhaust pipes thoroughly and still shuts the draft fan down after about an hour on high. Maybe it cant run on high but why put that unusable option there lol!

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It is likely fine with certain pellets, there can be a 20% difference in the heat flow through the stove just because of the pellets burned, this also can happen if you have the draft fan set too low for the feed rate heat builds up in the heat exchanger it can't get out into the room so that leaves the exhaust path and through the draft fan. If it can't get out fast enough that way the thermals on the draft (combustion blower) trip hopefully causing the stove to shut down due to a vacuum fault.

You have several control knobs to play with, reduce the high feed rate, increase the draft fan speed if it isn't at the top (send the heat up the flue), or increase the room (convection) fan speed sending the heat into the room.

At least you have the options available, just remember they can also be abused and put you in a world of hurt.

I never ran mine on HR-5 for more than a short period of time. Depending on what pellets you're burning that thing would put out A LOT of heat running on 5 for an hour or more. Must be a pretty big area you're heating. Did you take the room blower off auto and put it on 9 by chance?

I run mine on the stat on 3 or 4 depending on how cold it is outside. Those stoves can get loud but they can crank the heat pretty good!