We have an Air Ease Ultra80 oil furnace. (combo forced air heat/AC system). Model # LUF80A112/125D20-2 A

Last summer I installed a LUX programmable thermostat (TX9100E).

Had no issues with cooling in summer.

Now that the heat is coming on, I noticed the furnace is cycling differently than before.

The furnace always had a purge cycle at the end of the heat cycle, but now the unit is going through a short cycle BEFORE the heat cycle as well: the furnace fan comes on, runs for a few seconds (with NO HEAT produced), then shuts off. Then, a few seconds later, the fan AND burner come on, run the normal heat cycle, then a purge.

So, I'm getting a very short cycle of just the fan running, then shutting off, before I get a normal heat cycle. Make sense?

Any suggestions?

I tried changing the temp swing range on the stat, but that didn't have any effect.

I was also wondering if this is could be a two-stage furnace, and I need to wire the stat differently. Nothing in the furnace manual talks about it being a 2-stage, so I wired the stat according to instructions for a single-stage system. How do I confirm if this furnace is a single stage?