damm furnace wont keep up.
its 0° outside and 60° inside.
furnace will run for 8 minutes , shut off for 20 seconds , then fire back up for another 8 minutes.
why does it keep shutting itself off?

HELP!!!!! BURRRRRRrrrrrrrr

winter sucks

Is it a oil furnace or gas? If it is oil it may not be seeing the flame with the photographic eye. Also is your tank inside or outside? If outside you may be having a issue with the oil gelling up. If it is gas you could have a problem with the control box.

its a gas furnace. 15+ years old. seams like i have to get the furnace guy out every 2 years to replace something. hell , everything should be replaced by now.
why buy a new one

Is it a heat pump?

Duel fuel?

Are you sure it's lighting?

Is the circulating fan & the inducer fan running?

If its a heat pump is the outside unit running and sounding OK?

Who makes it?

What brand thermostat do you have?

Bad flame or fan sensor, could be a overheat switch too. Call the furnace guy. If it has a control board (electronic) It could be bad too. I just had the same thing on mine a week ago 0 outside and the best it could do was 66. It was a heat switch that was signalling too soon. replaced it and it has worked fine since.

not a heat pump.
not duel fuel.
it lights and runs fine .............i think.
i hear it fire up , a few seconds later the fan kicks on and blows warm air. it just wont run longer then 8 minutes or so.
dont know what brand any of it is and im at work now so i cant look.
had to come here to get warm

Well it sounds to like it has a cuircut or sensor problem, but it's hard to tell without being there. It might just be a bad thermostat.

This may sound stupid but have you changed your filter recently? You may have a clogged up filter and it is not allowing enough air to go over your exchanger and causing it to over heat (that would take about 10-15 min or so to happen. When the thing shuts off does the fan keep running or does that shut off also?

Jon

First thing I would do is eliminate the thermostat from the circuit in the event you have a bad thermostat. If you JUMPER "R" and "W" together, you are telling to furnace to run continuously. If the furnace runs, and runs, and runs, without any hiccups, then you have either a bad t-stat or t-stat wiring. If it continues to act up when jumpered, call a heating guy

hmmmmmm

when i get off work in going to vacuum out the "A" coil and see if that helps.
oh , and replace the filter too.