Contractor installed a new Lennox G71 furnace, XC21 AC unit, and corrected some of the undersized ductwork that was original to the home. The AC ability was dramatically improved, however we suddenly have noticed 1 small problem with the heating.
There are 2 second floor bedrooms which are the furthest rooms from the furnace. Despite being so far, they actually used to heat much better. The ac is fine with them (blower speed is definitely pressurizing all the ducts appropriately).
What I assume the problem is... is that the furnace works in 1% increments from 40% up to 100% and when the furnace is only working at say 40-60% the blower speed may not be enough to pressurize all the ducts. I don't think the furnace ever really kicks on at full speed - it seems to only run at low speed to maintain the temperature. I assume if it kicked on at 100% that it would heat fine, but then I lose the efficiency of the G71... Anyone else have this problem?