I have a 2700 sq ft rambler home with cathedral ceilings over a large portion of it - over the hallway, 2 living rooms and kitchen. We replaced the furnace that was installed when the home was built in 1982. This original furnace was a 115000 btu furnace. Unfortunately, we changed the furnce before we moved into this house a few months ago.
When the HVAC guys did a heat loss calculation they determined that the house needs about 80000 btu and installed a 80 % efficient 90000 btu Lennox (2 stage, variable speed).
The furnace runs constantly even when the temperature outside is 50 degrees and the thermostat is set to 62 degrees. Our utility bills are over 270 dollars for this setting.
The HVAC people have suggested adding more vents in the areas with the cathedral ceilings, changing the duct work to have a 2 zone system. In short they have asked us to modify the house so the furnace operated more efficiently.
I am wondering if the decrease in BTUs is causing the furnace to run constantly, even for low thermostat settings.