Have problem. I purchased a trane 3ton unit online but wasnot told it was only for cooling. my hvac contractor installed it and to his surprise discovered this.  he has tried to make it a heating unit also by adding a 4-way reversing valve and compressor. costed 800.00.  The aux. comes on. alot and the unit runs all the time when its below 35f. heat is set at 67f and if its 20f out it doesnt keep up. he says a 3 ton unit for a log home, if working right will do fine  due to thermal mass. i have 3000sq.ft. I think i need a new unit and a 4 ton unit. any sugg.

Agreed.

Best regards,

Bill

hey thanks for your input. My heat loss factor ranged from 80000 to 97000. u think 4 ton will do or would 5 tons be more effiec. I know there are many factors to consider but in general. we do burn some wood in a high effiec. insert

A 4 ton at best will only give you  55,000 btuh  at 50° EWT.  If your EWT is 30° you will only get  around 40,000 btuh.    What kind of loop do you have?