I notice most here dont use their furnace for backups unless it gets real cold. I assume it is for money savings reasons. But if I leave my furnace on 72deg and run my wood stove as much as possible - what else can it hurt, besides the pocketbook?? I have an outdoor air to air heatpump, with electric backup heat. If my thermostat senses 71, it kicks on. But heat pumps are not efficient if its too cold out - and if the thermostat gets to 70 then the electric heat kicks on. But with the woodstove, it may be telling the thermostat to only run the heatpump, assuming it is only down to 71deg but in reality it is way too cold outside for the heatpump to be efficient, and the electric heat needs to kick in like it would if the thermostat got to 70 - but it wont because of the wood stove. Whew - I hope that all made sence! Thoughts???