I've had a Resolute (probably III) for 28 years and the SS chimney is getting close to my comfort zone for safety of it's age. We've got a few extra issues and would like to relocate the stove, replace the chimney and ideally like to add 50% or more BTU since we now have way more fallen hardwood than I will ever burn (plus cost of alternate heat is now crazy expensive). We're looking at a good buy on a 4 yr. old zero clearance airtight fireplace rated at 55K BTU Max but in reality probably is 32K in regular use. The information I have seems to indicate that a good zero clearance fireplace vs. good wood stove is more aesthetic difference rather than performance (BTU). The Resolute is rated at 40K BTU but I can't locate anything that says if that is the maximum output or normal operational output. My suspicion is that I'm getting 10K at most out of it due to it being far less efficient than newer EPA approved designs and the current stove is definitely in need of a good overhaul so I'm getting 4 hr. burns now, compared to 6 to 8 hr. burns I got when newer. I'm also trying to guess it's output by comparing the heat I get from a 2.5K electric baseboard heater that is used when I'm too lazy to keep the stove going. A proper re-build is probably not much different in price than the deal on the fireplace, since so many people are getting rid of fireplaces due to insurance problems. I need to replace this unit with one that produces more BTU so I do not want to sink a ton of money into a replacement to discover that I'm not getting more heat. Yes, I understand that BTU's are very dependent upon type of wood, dryness, etc. but let's skip that and compare based on old design and efficiency and old ratings vs. newer ones since I'll be using identical wood. Appreciate comments.