Is the new furnace the same size btus as the old furnace?

Is the thermostat new?

I believe that you can adjust the "degree differential" on the thermostat which effects cycling.

Good luck.

Mike,
Did you do a manual-J for heat loss? Your new "high efficiency" furnace is what AFUE?

You were not clear if the furnace is over 90% AFUE and if the venting is with one or 2 pipes. If you matched the size of the furnace being replaced you are most likely over sized.

An easy way to determine the size of a new furnace is to multiply the input of the old unit by 60% then divide the efficiency of the new furnace into the result. For instance, if your old atmospheric furnace was 100,000 Btu times 60% = 60,000 Btu output. If your new furnace will be 94% AFUE divide 60,000 Btu by 94% =64,000 Btu. That is the input you need to match your old furnace. In this instance, if you match size for size the system will be 36% over sized.

Air sealing should not cause short cycling unless you restricted the combustion air. Did you install this system yourself? If you believe combustion air to be the problem, there are ways to measure the pressure in the furnace area to see if air is a problem.

Good luck,

If you haven't changed or touched the thermostats, then the increased cycling is due to an effective oversizing of the furnace as was pointed out. It will get worse as the outside temperature drops. You could reduce this by increasing the insulation to the heated area of the house and the following thermostat adjustments:
Increase the "swing" temperature to the maximum you can tolerate, say 2 or 3 degrees,or if your themostat has a setting for cycles that you can adjust downward. In either case, it boils down to the inverse relationship - decreasing cycling increases the "swing" or diffeential temperature and vice versa.
And, your sealing the basement should help the cycling problem slightly; the more you insulate, the longer it takes for the temperature to drop and, accordingly, there is a reduction in cycling rate. But your main focus should be on the heated areas.
If the problem is not mitigated, by these schemes, then you may considerunderfiring the furnace to reduce the heat output, but there may be inefficiencies associated with this. You would need a pro to advise you.

Stu/Joe:

Educate me on why a new high efficiency gas furnace would have to be reduced in btus to match the btus of the old furnace. I thought that the btus should be the same with a new furnace because that is the heating requirements of the house. I have a heat pump so I don't know much about gas furnaces.

Thanx.